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  • 101.
    Emanuelsson, Christian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Electronic Structure and Film Morphology Studies of PTCDI on Metal/Semiconductor Surfaces2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Organic semiconductors have received increasing attention over the last decades as potential alternatives for inorganic semiconductors. The properties of these films are highly dependent on their structural order. Of special interest is the interface between the film and its substrate, since the structure of the interface and the first few layers decide the growth of the rest of the film. The interface structure is determined by the substrate/molecule interactions, the intermolecular interactions and the growth conditions.

    In this thesis, thin films of the organic semiconductor PTCDI have been studied using complementary microscopy and spectroscopy techniques on two metal-induced surface reconstructions, Ag/Si(111)-√3×√3 and Sn/Si(111)-2√3×2√3. These surfaces were chosen because they have different reactivities and surface periodicities. On the weakly interacting Ag-terminated surface, the film growth is mainly governed by the intermolecular interactions. This leads to well-ordered films that grow layer-by-layer. The interaction with the substrate is through electron charge transfer to the molecules from the substrate. This results in two different types of molecules with different electronic structure, which are identified using both STM images and PES spectra. On the more strongly interacting Sn-terminated surface the molecules adsorb in specific adsorption geometries and form 1D rows. At around 0.5 ML coverage the rows also interact with each other and form a 4√3×2√3 reconstruction and beyond one ML coverage the growth is characterized as island growth. The interaction with the substrate is mainly due to heavy electron charge transfer from the Sn atoms in the substrate to the C atoms in the imide group, but also the N atoms and the perylene core in PTCDI are involved. In these systems, the interactions with the surfaces result in new states inside the HOMO-LUMO gap, and the intermolecular interactions are dominated by O···H and O···H-N hydrogen bondings.

  • 102.
    Emanuelsson, Christian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Scanning Electron Microscopy study of Macbat regeneration effect on lead-acid battery electrodes2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Electrodes from lead-acid batteries were studied using scanning electron microscopy and energy dispersive spectroscopy. This to observe the effects of cycling on the batteries and how a capacity recovery process, known as Macbat regeneration, affected the active material with focus on hard sulphation. First, two new batteries were cycled for two months and electrodes from them were studied when the batteries were new, cycled, fully charged after cycling and regenerated after cycling. Then electrodes from a separate battery that had been used in industry was studied prior to and after Macbat regeneration. On the cycled batteries it was found that after the cycling of the batteries no hard sulphation were present on the electrodes. The study of the separate battery showed that the battery had hard sulphation in its electrodes and that the Macbat regeneration was able to remove hard sulphation both on the surface of the electrodes and also inside the active material.

  • 103.
    Emanuelsson, Christian
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Johansson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Delicate Interactions of PTCDI molecules on Ag/Si(111)-√3×√32018Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 149, nr 16, s. 164707-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PTCDI molecules were evaporated onto a Ag/Si(111)√3×√3 surface and studied using scanning tun-resolution STM images are used to identify the delicate molecule/molecule and molecule/substrate interactions and the shapes of the molecular orbitals. The results show that the substrate/molecule interaction strongly modifies the electronic configuration of the molecules as their orbital shapes are quite different at 1 and 2 monolayer (ML) coverage. Simple models of molecular HOMO/LUMO levels and intermolecular hydrogen-bondings have been made for 1 and 2 ML PTCDI coverages to explain the STM images. Changes due to the interaction with the substrate are also found in ARUPS as extra states above the regular HOMO level at 1 ML PTCDI coverage. The ARUPS data also show that the electronic structure of the substrate remains unchanged after the deposition of molecules as the dispersion of the substrate related bands is unchanged. The changes in electronic structure ofthe molecules are discussed based on aHOMO/LUMO split.

  • 104.
    Emanuelsson, Christian
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Johansson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Photoelectron spectroscopy studies of PTCDI on Ag/Si(111)-root 3 x root 32018Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 149, nr 4, artikkel-id 044702Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    3,4,9,10-perylene tetracarboxylic diimide molecules were evaporated onto a Ag/Si(111)-root 3 x root 3 surface and studied using photoelectron spectroscopy and near edge X-ray absorption fine structure (NEXAFS). All core levels related to the imide group of the molecules showed a partial shift to lower binding energies at low coverages. In NEXAFS spectra, the first transitions to the unoccupied states were weaker at low coverages compared to thicker films. Also, extra states in the valence band between the regular highest occupied molecular orbital and the Fermi level were found at low coverages. These changes were explained by two types of molecules. Due to charge transfer from the surface, these two types have different interactions between the imide group and the substrate. As a result, one type has a partially filled lowest unoccupied molecular orbital while the other type does not. Published by AIP Publishing.

  • 105.
    Emanuelsson, Christian
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Johansson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Photoelectron spectroscopy studies of PTCDI on Sn/Si(111)-2√3×2√3Manuskript (preprint) (Annet vitenskapelig)
  • 106.
    Emanuelsson, Christian
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Soldemo, Markus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Johansson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Scanning tunneling microscopy study of PTCDI on Sn/Si(111)-2√3×2√32019Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Perylene tetracarboxylic diimide molecules were evaporated onto a Sn/Si(111)-2 root 3 x 2 root 3 surface and studied using scanning tunneling microscopy (STM) and low energy electron diffraction. At low coverages, single molecules are locked into specific adsorption geometries, which are investigated in detail using high resolution STM. The electronic structure of these individual molecules was studied using bias dependent STM images. The molecules form 1D rows that become more common with increasing coverages. Possible intermolecular O center dot center dot center dot H interactions within the rows have been identified. At around half of a monolayer (ML), the rows of molecules interact with each other and form a commensurate 4 root 3 x 2 root 3 reconstruction. In a complete monolayer, several structures emerge as molecules fill in the space between the 4 root 3 x 2 root 3 stripes. Possible intermolecular interactions within the 1 ML structures have been discussed. At coverages above 1 ML, the growth is characterized by island growth, where the molecules are arranged according to the canted structure within the layers.

  • 107.
    Emanuelsson, Christian
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Johansson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Scanning tunneling microscopy study of thin PTCDI films on Ag/Si(111)-root 3 x root 32017Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, nr 11, artikkel-id 114702Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    3,4,9,10-perylene tetracarboxylic diimide molecules were evaporated onto a Ag/Si(111)-root 3 x root 3 surface and studied by scanning tunneling microscopy/spectroscopy and low energy electron diffraction (LEED). The growth mode was characterized as layer-by-layer growth with a single molecular unit cell in a short range order. The growth of the first two monolayers involves a molecule/substrate superstructure and a molecule/molecule superstructure. At higher coverages, the molecules in each layer were found to align so that unit cells are on top of each other. The experimentally obtained LEED pattern is described as a combination of patterns from the molecular unit cell and the molecule/substrate superstructure. The electronic structure was found to be strongly dependent on the film thickness for the first few layers: Several extra states are found at low coverages compared to higher coverages resulting in a very small pseudo gap of 0.9 eV for the first layer, which widens up to 4.0 eV for thicker films.

  • 108.
    Enmark, Martin
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Glenne, Emelie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Leśko, Marek
    Rzeszów University of Technology, Poland.
    Langborg Weinmann, Annika
    AstraZeneca.
    Leek, Tomas
    AstraZeneca.
    Kaczmarski, Krzysztof
    AstraZeneca.
    Klarqvist, Magnus
    AstraZeneca.
    Samuelsson, Jörgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Fornstedt, Torgny
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Investigation of robustness for supercritical fluid chromatography separation of peptides: Isocratic vs gradient mode2018Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1568, s. 177-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated and compared the robustness of supercritical fluid chromatography (SFC) separations of the peptide gramicidin, using either isocratic or gradient elution. This was done using design of experiments in a design space of co-solvent fraction, water mass fraction in co-solvent, pressure, and temperature. The density of the eluent (CO2-MeOH-H2O) was experimentally determined using a Coriolis mass flow meter to calculate the volumetric flow rate required by the design. For both retention models, the most important factor was the total co-solvent fraction and water mass fraction in co-solvent. Comparing the elution modes, we found that gradient elution was more than three times more robust than isocratic elution. We also observed a relationship between the sensitivity to changes and the gradient steepness and used this to draw general conclusions beyond the studied experimental system. To test the robustness in a practical context, both the isocratic and gradient separations were transferred to another laboratory. The gradient elution was highly reproducible between laboratories, whereas the isocratic system was not. Using measurements of the actual operational conditions (not the set system conditions), the isocratic deviation was quantitatively explained using the retention model. The findings indicate the benefits of using gradient elution in SFC as well as the importance of measuring the actual operational conditions to be able to explain observed differences between laboratories when conducting method transfer.

  • 109.
    Enochsson, Ann-Britt
    et al.
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för pedagogiska studier (from 2013).
    Kilbrink, Nina
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för pedagogiska studier (from 2013). Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013), Science, Mathematics and Engineering Education Research (SMEER).
    Andersén, Annelie
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för pedagogiska studier (from 2013).
    Ådefors, Annica
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för pedagogiska studier (from 2013).
    Teachers’ work with digital technology as boundary objects in vocational education2019Inngår i: NERA 2019 Abstract Book, 2019, s. 440-Konferansepaper (Fagfellevurdert)
  • 110.
    Ericsson, Leif
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Blazinic, Vanja
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Moons, Ellen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Effects of the morphology on the photodegradation of TQ1:PC70BM film: an AFM-IR studyManuskript (preprint) (Annet vitenskapelig)
  • 111.
    Ericsson, Leif K E
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Magnusson, Kjell
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    AFM and STM Study of ZnO NanoplatesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The surface morphology and electronic structure of hexagonal ZnO nanoplates have been studied by Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM). It was found that these nanoplates are terminated by their polar (0001) surfaces. The AFM investigation was performed in the ambient conditions with the nanocrystals “as grown”. Surprisingly, the AFM images of the top surfaces revealed an interesting triangular reconstruction, which was earlier observed only after cycles of sputtering and annealing of the ZnO(0001) surface in Ultra High Vacuum (UHV) systems. The surface atomic and electronic structures of these nanoplates have been further studied by STM and Scanning Tunneling Spectroscopy (STS) in UHV. The STM images also showed a triangular structure with single atomic steps. In addition, a 2x2 surface reconstruction has been observed with high resolution STM. This reconstruction agrees well with the recently proposed model that involves the removal of 1/4 of the topmost Zn atoms on the ZnO(0001) surface.

  • 112.
    Ericsson, Leif KE
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Growth and Characterization of ZnO Nanocrystals2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The understanding of surfaces of materials is of crucial importance to all of us. Considering nanocrystals (NCs), that have a large surface to bulk ratio, the surfaces become even more important. Therefore, it is important to understand the fundamental surface properties in order to use NCs efficiently in applications. In the work reported in this thesis ZnO NCs were studied.

    At MAX-lab in Lund, synchrotron radiation based Spectroscopic Photoemission and Low Energy Electron Microscopy (SPELEEM) and X-ray Photoelectron Spectroscopy (XPS) were used. At Karlstad University characterization was done using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Scanning Tunnelling Microscopy (STM), Auger Electron Spectroscopy (AES), and XPS.

    The fundamental properties of ZnO surfaces were studied using distributions of ZnO NCs on SiO2/Si surfaces. The conditions for distribution of ZnO NCs were determined to be beneficial when using ethanol as the solvent for ultrasonically treated dispersions. Annealing at 650 °C in UHV cleaned the surfaces of the ZnO NCs enough for sharp LEEM imaging and chemical characterization while no sign of de-composition was found. A flat energy band structure for the ZnO/SiO2/Si system was proposed after 650 °C. Increasing the annealing temperature to 700 °C causes a de-composition of the ZnO that induce a downward band bending on the surfaces of ZnO NCs.

    Flat ZnO NCs with predominantly polar surfaces were grown using a rapid microwave assisted process. Tuning the chemistry in the growth solution the growth was restricted to only plate-shaped crystals, i.e. a very uniform growth. The surfaces of the NCs were characterized using AFM, revealing a triangular reconstruction of the ZnO(0001) surface not seen without surface treatment at ambient conditions before. Following cycles of sputtering and annealing in UHV, we observe by STM a surface reconstruction interpreted as 2x2 with 1/4 missing Zn atoms.

  • 113.
    Ericsson, Leif
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Magnusson, Kjell
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Microwave assisted rapid growth of flat ZnO(0001) platelets2013Manuskript (preprint) (Annet vitenskapelig)
  • 114.
    Ericsson, Leif
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Magnusson, Kjell
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Preparation of ZnO nanocrystals for individual surface analysis2013Manuskript (preprint) (Annet vitenskapelig)
  • 115.
    Eriksson, Daniel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Grasping of Non-Rigid Objects: Relation Between Physical Properties and Subjective Experiences2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
  • 116.
    Eriksson, Karl-Erik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Reduction of the Wave-packet Can Be Understood Within Quantum Mechanics2012Inngår i: Foundations of Probability and Physics - 6, American Institute of Physics (AIP), 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A quantum-mechanical model is constructed for a microscopic quantum system in interaction with a macroscopic measurement apparatus (described by a large number of stochastic variables). The theoretical framework is scattering theory of quantum field theory with unitary time evolution. Within this model, the Born rule is obtained in the thermodynamic limit of infinitely many stochastic variables.

  • 117.
    Eriksson, Olof
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Radiation exposure to personnel during fluoroscopic procedures: Strålningsmiljö för personal under genomlysningsarbete2018Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    There are about 17 million X-ray procedures performed in Sweden every year. Various methods are used to determine the risk for the patient, and for the staff. The objective of this project was to map X-ray scatter coming out of a patient as a result of interactions between the radiation and body tissue during certain medical procedures that involve fluoroscopy. Flouroscopy is a type of X-ray imaging method that generates a moving picture which allows an operator to view in-body procedures live. A successfully created map of the radiation field can work as a tool for risk analysis concerning the dose of radiation of which the medical staff is exposed to, this parameter will later be described as the effective dose (E). The effective dose is a tool for assessment of the risk of developing lethal cancer due to radiation exposure. This report will also investigate the radiation that reaches the eye lens of the staff, since the maximum recommended dosage for the eye lens has been lowered recently when it was discovered that the eye lens was more sensitive to radiation than previously known. In this report data was collected from radiation exposure situations, and it was concluded that distance is a good protector against radiation, which agree well with theory discussed in the report. Another theory which was discussed in the paper states that positions behind the X-ray tube will be exposed to the highest amount of radiation, this was also proven. The measured data from investigating protective equipment showed that the equipment in place was effective.

  • 118.
    Farinhas, Joana
    et al.
    Inst Super Tecn, Inst Telecomunicacoes, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Oliveira, Ricardo
    Inst Super Tecn, Inst Telecomunicacoes, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Ericsson, Leif
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Morgado, Jorge
    Inst Super Tecn, Inst Telecomunicacoes, Av Rovisco Pais, P-1049001 Lisbon, Portugal.;Univ Lisbon, Inst Super Tecn, Dept Bioengn, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Charas, Ana
    Inst Super Tecn, Inst Telecomunicacoes, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Efficient ternary organic solar cells based on immiscible blends2017Inngår i: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 41, s. 130-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic photovoltaic cells based on ternary blends of materials with complementary properties represent an approach to improve the photon-absorption and/or charge transport within the devices. However, the more complex nature of the ternary system, i.e. in diversity of materials' properties and morphological features, complicates the understanding of the processes behind such optimizations. Here, organic photovoltaic cells with wider absorption spectrum composed of two electron-donor polymers, F8T2, poly(9,9-dioctylfluorene-alt-bithiophene), and PTB7, poly([4,8-bis[(2'-ethylhexyl) oxy] benzo[1,2-b: 4,5-b'] dithiophene-2,6-diyl][3-fluoro-2-[(2'-ethylhexyl) carbonyl] thieno[3,4-b] thiophenediyl]), mixed with [6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) are investigated. We demonstrate an improvement of 25% in power conversion efficiency in comparison with the most efficient binary blend control devices. The active layers of these ternary cells exhibit gross phase separation, as determined by Atomic Force Microscopy (AFM) and Synchrotron-based Scanning Transmission X-ray Microscopy (STXM).

  • 119.
    Fernandes, R
    et al.
    Texas A&M University.
    El-Borgi,
    Texas A&M University at Qatar.
    Mousavi, Mahmoud
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Reddy, JN
    Texas A&M University.
    Mechmoum,
    Texas A&M University at Qatar.
    Nonlinear size-dependent longitudinal vibration of carbon nanotubesembedded in an elastic medium2017Inngår i: Physica E: Low-dimensional Systems and Nanostructures, ISSN 1386-9477, Vol. 88, s. 18-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we study the longitudinal linear and nonlinear free vibration response of a single walled carbonnanotube (CNT) embedded in an elastic medium subjected to different boundary conditions. This formulation isbased on a large deformation analysis in which the linear and nonlinear von Kármán strains and their gradientare included in the expression of the strain energy and the velocity and its gradient are taken into account in theexpression of the kinetic energy. Therefore, static and kinetic length scales associated with both energies areintroduced to model size effects. The governing motion equation along with the boundary conditions are derivedusing Hamilton's principle. Closed-form solutions for the linear free vibration problem of the embedded CNTrod are first obtained. Then, the nonlinear free vibration response is investigated for various values of lengthscales using the method of multiple scales.

  • 120.
    Fjelstad, Jens
    et al.
    Nanjing University, Nanjing, China.
    Fuchs, Jürgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Stigner, Carl
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University, Germany.
    Partition functions, mapping class groups and Drinfeld doubles2013Inngår i: Symmetries and Groups in Contemporary Physics: Proceedings of the XXIX International Colloquium on Group-Theoretical Methods in Physics / [ed] Chengming Bai (Nankai University, China), Jean-Pierre Gazeau (Paris Diderot University, France), Mo-Lin Ge (Nankai University, China), Singapore: World Scientific, 2013, s. 405-410Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Higher genus partition functions of two-dimensional conformal field theories have to be invariants under linear actions of mapping class groups. We illustrate recent results [4,6] on the construction of such invariants by concrete expressions obtained for the case of Drinfeld doubles of finite groups. The results for doubles are independent of the characteristic of the underlying field, and the general results do not require any assumptions of semisimplicity.

  • 121.
    Flygare, Mattias
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Non-abelian braiding in abelian lattice models from lattice dislocations2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Topological order is a new field of research involving exotic physics. Among other things it has been suggested as a means for realising fault-tolerant quantum computation. Topological degeneracy, i.e. the ground state degeneracy of a topologically ordered state, is one of the quantities that have been used to characterize such states. Topological order has also been suggested as a possible quantum information storage.

    We study two-dimensional lattice models defined on a closed manifold, specifically on a torus, and find that these systems exhibit topological degeneracy proportional to the genus of the manifold on which they are defined. We also find that the addition of lattice dislocations increases the ground state degeneracy, a behaviour that can be interpreted as artificially increasing the genus of the manifold. We derive the fusion and braiding rules of the model, which are then used to calculate the braiding properties of the dislocations themselves. These turn out to resemble non-abelian anyons, a property that is important for the possibility to achieve universal quantum computation. One can also emulate lattice dislocations synthetically, by adding an external field. This makes them more realistic for potential experimental realisations.

  • 122.
    Flygare, Mattias
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Svensson, Krister
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Quantifying crystallinity in carbon nanotubes and its influence on mechanical behaviour2019Inngår i: Materials Today Communications, ISSN 2352-4928, Vol. 18, s. 39-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The different fabrication methods that have been developed for making carbon nanotubes will provide materials with different levels of crystallinity. As crystallinity is qualitatively known to have a profound influence on material properties, this raises the need for standardised quantitative analysis. Here we show how transmission electron microscopy can be used to provide quantitative information about effective crystallite sizes in individual nanotubes which we link to the mechanical behaviour of the tubes. The method relies on a thorough analysis of diffraction patterns and a careful extraction of instrumental and sample contributions to the peak shapes. We find that arc-discharge grown tubes have crystallite sizes that are comparable to the circumference of the outer tube walls, while commercial catalytically grown tubes have much smaller crystallites implying that each cylindrical nanotube wall can be thought of as a patchwork of small graphene-like grains. The clear differences in crystallite sizes are then compared to known differences in mechanical behaviour, such as a substantial disparity in stiffness and significantly different behaviours under bending stress.

  • 123.
    Fornstedt, Torgny
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Åsberg, Dennis
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Lesko, Marek
    Rzeszow University of Technology.
    Enmark, Martin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Forssén, Patrik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Samuelsson, Jörgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Kaczmarski, Krzysztof
    Rzeszow University of Technology.
    New Procedure for Predictions of Overloaded Profiles in Gradient Elution2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    To simulate the separation process in liquid chromatography, the competitive adsorption isotherms need to be known. In gradient elution, the adsorption isotherms are determined with isocratic experiments on different mobile-phase plateaus, levels covering the range used in the gradient program. This can lead to extreme retention times for some mobile-phase compositions and therefore it might even be impossible to determine all necessary adsorption data using the traditional isocratic approach. In this talk, we will present a method where single and competitive nonlinear adsorption isotherms are determined directly from overloaded elution profiles in gradient elution. The numerical coefficients in the adsorption isotherms are determined by the inverse method that minimizes the difference between calculated and experimental elution profiles. This is a new method where the need for tedious/impossible isocratic experiments is eliminated. The method is systematically verified using both synthetic and experimental data. Finally the new method is used to successfully predict elution profiles for a two-component mixture in gradient elution. The new method open up the opportunity to study the adsorption of substances whose retention factor vary strongly with the mobile-phase composition, like peptides and proteins, where the classic methods will fail. We also intend to transfer the metholology for SFC in near future; but there are some problems to be solved first (see our SFC posters). This is a contribution from the Fundamental Separation Science Group www.FSSG.se

  • 124.
    Fredriksson, Mårten
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Syftet med NTA i kemi: Fjärdeklasselevers uppfattning av syftet jämfört med lärarens syfte2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Syftet med min undersökning var att bidra med ökade kunskaper om vilka uppfattningar som finns bland fjärdeklasselever gällande syftet med NTA i kemi, och om dessa överensstämmer med lärarens syfte. Datainsamlingen har gjorts via gruppintervjuer med femton elever och deras lärare. Intervjusvaren har sedan kategoriserats induktivt. Resultatet har visat att eleverna inte uppfattar syftet med NTA-lådan så som läraren tänkt. Det verkar som att eleverna ser ett mer närliggande syfte och fokuserar på vad som händer. Läraren, å andra sidan, tycks ha ett mer övergripande syfte som utgår från kunskapskraven men som hon inte fullt ut lyckas kommunicera till eleverna. Hon syftar även till att eleverna utvecklar sin resonemangsförmåga genom diskussioner i helklass. Eleverna tycker dessutom att helkassdiskussionerna är intressanta och lärorika. Tid läggs på diskussionerna vilket ger en möjlighet till en naturvetenskaplig literacitet.

  • 125.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Gannon, Terry
    University of Alberta, Edmonton, Canada.
    Schaumann, Gregor
    Universität Wien, Austria.
    Schweigert, Christoph
    Universität Hamburg, Germany.
    The logarithmic Cardy case: Boundary states and annuli2018Inngår i: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 930, s. 287-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a model-independent study of boundary states in the Cardy case that covers all conformal field theories for which the representation category of the chiral algebra is a – not necessarily semisimple – modular tensor category. This class, which we call finite CFTs, includes all rational theories, but goes much beyond these, and in particular comprises many logarithmic conformal field theories. We show that the following two postulates for a Cardy case are compatible beyond rational CFT and lead to a universal description of boundary states that realizes a standard mathematical setup: First, for bulk fields, the pairing of left and right movers is given by (a coend involving) charge conjugation; and second, the boundary conditions are given by the objects of the category of chiral data. For rational theories our proposal reproduces the familiar result for the boundary states of the Cardy case. Further, with the help of sewing we compute annulus amplitudes. Our results show in particular that these possess an interpretation as partition functions, a constraint that for generic finite CFTs is much more restrictive than for rational ones.

  • 126.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schaumann, Gregor
    Max-Planck-Institut für Mathematik, Bonn.
    Schweigert, Christoph
    Hamburg University.
    A trace for bimodule categories2017Inngår i: Applied Categorical Structures, ISSN 0927-2852, E-ISSN 1572-9095, Vol. 25, nr 2, s. 227-268Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study a 2-functor that assigns to a bimodule category over a finite k-linear tensor category a k-linear abelian category. This 2-functor can be regarded as a category-valued tracefor 1-morphisms in the tricategory of finite tensor categories. It is defined by a universalproperty that is a categorification of Hochschild homology of bimodules over an algebra.We present several equivalent realizations of this 2-functor and show that it has a coherent cyclic invariance.Our results have applications to categories associated to circles in three-dimensional topological field theories with defects. This is made explicit for the subclass of Dijkgraaf-Wittentopological field theories.

  • 127.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schaumann, Gregor
    Universität Wien, Austria.
    Schweigert, Christoph
    Universität Hamburg, Germany.
    Eilenberg-Watts calculus for finite categories and a bimodule Radford S4 theorem2019Inngår i: Transactions of the American Mathematical Society, ISSN 0002-9947, E-ISSN 1088-6850Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We obtain Morita invariant versions of Eilenberg-Watts type the-orems, relating Deligne products of finite linear categories to categories of leftexact as well as of right exact functors. This makes it possible to switch be-tween different functor categories as well as Deligne products, which is oftenvery convenient. For instance, we can show that applying the equivalence fromleft exact to right exact functors to the identity functor, regarded as a left exactfunctor, gives a Nakayama functor. The equivalences of categories we exhibitare compatible with the structure of module categories over finite tensor cat-egories. This leads to a generalization of Radford’sS4-theorem to bimodulecategories. We also explain the relation of our construction to relative Serrefunctors on module categories that are constructed via inner Hom functors.

  • 128.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, C.
    Universität Hamburg.
    Full Logarithmic Conformal Field theory — an Attempt at a Status Report: LMS/EPSRC Durham Symposium on Higher Structures in M-Theory2019Inngår i: Fortschritte der Physik, ISSN 0015-8208, E-ISSN 1521-3978, artikkel-id 1910018Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Logarithmic conformal field theories are based on vertex algebras with non-semisimple representation categories. While examples of such theories have been known for more than 25 years, some crucial aspects of local logarithmic CFTs have been understood only recently, with the help of a description of conformal blocks by modular functors. We present some of these results, both about bulk fields and about boundary fields and boundary states. We also describe some recent progress towards a derived modular functor. This is a summary of work with Terry Gannon, Simon Lentner, Svea Mierach, Gregor Schaumann and Yorck Sommerhäuser.

  • 129.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Schweigert, Christoph
    A note on permutation twist defects in topological bilayer phases2014Inngår i: Letters in Mathematical Physics, ISSN 0377-9017, E-ISSN 1573-0530, Vol. 104, nr 1, s. 1385-1405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a mathematical derivation of some of the most important physical quantities arising in topological bilayer systems with permutation twist defects as introduced by Barkeshli et al. in cond-mat/1208.4834. A crucial tool is the theory of permutation equivariant modular functors developed by Barmeier et al. in math.CT/0812.0986 and math.QA/1004.1825.

  • 130.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Universität Hamburg, Germany.
    Categorical tools for state sum constructions2016Inngår i: Proceedings in Applied Mathematics and Mechanics: PAMM, ISSN 1617-7061, E-ISSN 1617-7061, Vol. 16, nr 1, s. 911-912Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface defects in (extended) three‐dimensional topological field theories have important applications, ranging from solid state physics to computations of Brauer‐Picard groups of representation categories. We present some categorical tools that are needed in such a construction, including in particular a category‐valued trace.

  • 131.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University.
    Coends in conformal field theory2017Inngår i: Lie Algebras, Vertex Operator Algebras, and Related Topics / [ed] Katrina Barron, Elizabeth Jurisich, Antun Milas, Kailash Misra, American Mathematical Society (AMS), 2017, s. 65-81Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The idea of "summing over all intermediate states" that is central for implementing locality in quantum systems can be realized by coend constructions. In the concrete case of systems of conformal blocks for a certain class of conformal vertex algebras, one deals with coends in functor categories. Working with these coends involves quite a few subtleties which, even though they have in principle already been understood twenty years ago, have not been sufficiently appreciated by the conformal field theory community.

  • 132.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University.
    Consistent systems of correlators in non-semisimple conformal field theory2017Inngår i: Advances in Mathematics, ISSN 0001-8708, E-ISSN 1090-2082, Vol. 307, s. 598-639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on the modular functor associated with a -- not necessarily semisimple -- finite non-degenerate ribbon category D, we present a definition of a consistent system of bulk field correlators for a conformal field theory which comprises invariance under mapping class group actions and compatibility with the sewing of surfaces. We show that when restricting to surfaces of genus zero such systems are in bijection with commutative symmetric Frobenius algebras in D, while for surfaces of any genus they are in bijection with modular Frobenius algebras in D. This provides additional insight into structures familiar from rational conformal field theories and extends them to rigid logarithmic conformal field theories.

  • 133.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). Karlstads Univ, Teoret Fys, Univ Gatan 21, S-65188 Karlstad, Sweden..
    Schweigert, Christoph
    Univ Hamburg, Fachbereich Math, Algebra & Zahlentheorie, Bundesstr 55, D-20148 Hamburg, Germany..
    Low-dimensional topology, low-dimensional field theory and representation theory2017Inngår i: Representation theory: Current trends and perspectives / [ed] Krause, H Littelmann, P Malle, G Neeb, KH Schweigert, C, European Mathematical Society Publishing House, 2017, s. 255-267Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Structures in low-dimensional topology and low-dimensional geometry often combined with ideas from (quantum) field theory can explain and inspire concepts in algebra and in representation theory and their categorified versions. We present a personal view on some of these instances which have appeared within the Research Priority Programme SPP 1388 "Representation theory".

  • 134.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University.
    Symmetries and defects in three-dimensional topological field theory2016Inngår i: Proceedings of Symposia in Pure Mathematics, Providence: American Mathematical Society (AMS), 2016, Vol. 93, s. 21-40Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Boundary conditions and defects of any codimension are natural parts of any quantum field theory. Surface defects in three-dimensionaltopological field theories of Turaev-Reshetikhin type have applications to two-dimensional conformal field theories, in solid state physics and in quantumcomputing. We explain an obstruction to the existence of surface defects thattakes values in a Witt group. We then turn to surface defects in Dijkgraaf-Witten theories and their construction in terms of relative bundles; this allowsone to exhibit Brauer-Picard groups as symmetry groups of three-dimensionaltopological field theories.

  • 135.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University, Germany.
    Stigner, Carl
    Camatec industriteknik AB Karlstad.
    From non-semisimple Hopf algebras to correlation functions for logarithmic CFT2013Inngår i: Journal of Physics A: Mathematical and General, ISSN 0305-4470, E-ISSN 1361-6447, Vol. 46, nr 49Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use factorizable finite tensor categories, and specifically the representation categories of factorizable ribbon Hopf algebras H, as a laboratory for exploring bulk correlation functions in local logarithmic conformal field theories. For any ribbon Hopf algebra automorphism ω of H, we present a candidate for the space of bulk fields and endow it with a natural structure of a commutative symmetric Frobenius algebra. We derive an expression for the corresponding bulk partition functions as bilinear combinations of irreducible characters; as a crucial ingredient this involves the Cartan matrix of the category. We also show how for any candidate bulk state space of the type we consider, correlation functions of bulk fields for closed oriented world sheets of any genus can be constructed that are invariant under the natural action of the relevant mapping class group

  • 136.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Schweigert, Christoph
    Hamburg University.
    Stigner, Carl
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Higher genus mapping class group invariants from factorizable Hopf algebras2014Inngår i: Advances in Mathematics, ISSN 0001-8708, E-ISSN 1090-2082, Vol. 250, s. 285-319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lyubashenko's construction associates representations of mapping class groups Map_{g,n} of Riemann surfaces of any genus g with any number n of holes to a factorizable ribbon category. We consider this construction as applied to the category of bimodules over a finite-dimensional factorizable ribbon Hopf algebra H. For any such Hopf algebra we find an invariant of Map_{g,n} for all values of g and n. More generally, we obtain such invariants for any pair (H,omega), where omega is a ribbon automorphism of H. Our results are motivated by the quest to understand correlation functions of bulk fields in two-dimensional conformal field theories with chiral algebras that are not necessarily semisimple, so-called logarithmic conformal field theories.

  • 137.
    Fuchs, Jürgen
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Schweigert, Christoph
    Valentino, Alessandro
    A geometric approach to boundaries and surface defects in Dijkgraaf-Witten theories2014Inngår i: Communications in Mathematical Physics, ISSN 0010-3616, E-ISSN 1432-0916, Vol. 332, s. 981-1015Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dijkgraaf-Witten theories are extended three-dimensional topological field theories of Turaev-Viro type. They can be constructed geometrically from categories of bundles via linearization. Boundaries and surface defects or interfaces in quantum field theories are of interest in various applications and provide structural insight. We perform a geometric study of boundary conditions and surface defects in Dijkgraaf-Witten theories. A crucial tool is the linearization of categories of relative bundles. We present the categories of generalized Wilson lines produced by such a linearization procedure. We establish that they agree with the Wilson line categories that are predicted by the general formalism for boundary conditions and surface defects in three-dimensional topological field theories that has been developed in arXive:1203.4568.

  • 138.
    Garcia, Gustavo
    et al.
    Nara Institute of Science and Technology.
    Solis, Jorge
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Takamatsu, J.
    Nara Institute of Science and Technology.
    Ogasawara, T.
    Nara Institute of Science and Technology.
    Quantitative Comfort Evaluation of Eating Assistive Devices based on Human Effort Estimation using an Accelerometer2019Konferansepaper (Fagfellevurdert)
  • 139. Garcia Ricardez, G. A.
    et al.
    Solis, Jorge
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Takamatsu, J.
    Ogasawara, T.
    Interaction Force Estimation for Quantitative Comfort Evaluation of an Eating Assistive Device2018Inngår i: HRI '18 Companion of the 2018 ACM/IEEE International Conference on Human-Robot Interaction, Association for Computing Machinery (ACM), 2018, s. 113-114Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robots usage in the fields of human support and healthcare is wide-spreading. Robotic devices to assist humans in the self-feeding task have been developed to help patients with limited mobility in the upper limbs but the acceptance of these robots has been limited. In this work, we investigate how to quantitatively evaluate the comfort of an eating assistive device by estimating the interaction forces between the human and the robot when eating. We experimentally verify our concept with a commercially-available eating assistive device and a human subject. The evaluation results demonstrate the feasibility of our approach.

  • 140.
    Garcia Ricardez, Gustavo Alfonso
    et al.
    Nara Institute of Science and Technology, Japan.
    Takamatsu, Jun
    Nara Institute of Science and Technology, Japan.
    Ogasawara, Tsukasa
    Nara Institute of Science and Technology, Japan.
    Solis, Jorge
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Quantitative Comfort Evaluation of Eating Assistive Devices based on Interaction Forces Estimation using an Accelerometer2018Inngår i: RO-MAN 2018 - 27th IEEE International Symposium on Robot and Human Interactive Communication, IEEE, 2018, s. 909-914Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robot usage in the fields of human support and healthcare is expanding. Robotic devices to assist humans in the self-feeding task have been developed to help patients with limited mobility in the upper limbs but the acceptance of these robots has been limited. In this work, we investigate how to quantitatively evaluate the comfort of an eating assistive device by estimating the interaction forces between the human and the robot when eating. Rather than using expensive or commercially unavailable devices to directly measure the forces involved in feeding, we use an accelerometer to estimate these forces, which are calculated using a previously observed estimation of the system mass and the measured acceleration during the feeding process. We experimentally verify our concept with a commercially-available eating assistive device and a human subject. The evaluation results demonstrate the feasibility of our approach.

  • 141.
    George, Zandra
    et al.
    Chalmers, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Xia, Yuxin
    Linkoping Univ, IFM, Biomol & Organ Elect, SE-58183 Linkoping, Sweden.;Linkoping Univ, Ctr Organ Elect, SE-58183 Linkoping, Sweden..
    Sharma, Anirudh
    Univ S Australia, Future Ind Inst, Mawson Lakes, SA 5095292, Australia..
    Lindqvist, Camilla
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Andersson, Gunther
    Flinders Univ S Australia, Flinders Ctr NanoScale Sci & Technol, Sturt Rd,Bedford Pk, Adelaide, SA 5042, Australia..
    Inganas, Olle
    Linkoping Univ, IFM, Biomol & Organ Elect, SE-58183 Linkoping, Sweden.;Linkoping Univ, Ctr Organ Elect, SE-58183 Linkoping, Sweden..
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Muller, Christian
    Chalmers, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Andersson, Mats R.
    Chalmers, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Univ S Australia, Future Ind Inst, Mawson Lakes, SA 5095292, Australia..
    Two-in-one: Cathode modification and improved solar cell blend stability through addition of modified fullerenes2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 7, s. 2663-2669Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of dual purpose modified fullerenes with pyridine-as well as amine-functional groups is reported. Addition of these fullerenes to a polymer : fullerene bulk-heterojunction blend based on a thiophene-quinoxaline donor polymer is found to modify the active layer/cathode interface of inverted solar cells (glass/ITO/active layer/MoO3/Al). In particular the open-circuit voltage of devices is increased from 0.1 V to about 0.7 V, which results in a drastic rise in photovoltaic performance with a power conversion efficiency of up to 3%. At the same time, presence of the functionalised fullerene additives prevents the detrimental formation of micrometre-sized fullerene crystals upon annealing at 140 degrees C. As a result, the device performance is retained, which promises significantly increased thermal stability of the bulk-heterojunction blend nanostructure.

  • 142.
    Glaad, Gustaf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Pressurizing of high-pressure fuel system forsingle cylinder test cell2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis covers the development of a high-pressure fuel system for compression ignitedfuels such as diesel and diesel-like fuels that will be deployed into a single cylinder test cell at AVLMTC Södertälje, Sweden. The test cell is used by AVL to conduct research and testing of new fuelsfor their customers and this new fuel system will widen the span of fuels able to be tested by theequipment.This thesis focuses on pumping and pressurizing of the fuel, ensuring that all ingoing materialsare non-corrosive in this environment and compatible with the necessary fuels and lastly a safetyanalysis of the system with respect to operator and process safety. Other aspects of the projectsuch as mass flow measurements and fuel conditioning is covered in a sister thesis Mass flowrate measurement of compression ignition fuels in high-pressure stand-alone pump unit for singlecylinder test cell written by C. Aksoy [1].The goal of this thesis project was to deliver a finished manufactured fuel system and if the timeallowed for it, also validate its performance and finally installing and incorporating it into the singlecylinder test cell. The development process started with the writing of a product specificationoutlining the requirements and request on the product in a specification of requirements matrix andrelate these to product properties of the system using a quality function deployment (QFD) matrix.This document was then used as a base for further advancement in developing concepts to solveeach product property and weighing these concepts against each other using Pugh’s matrices. Thechosen concepts were then further developed, a flow chart for the system was developed as well asfuel lines and other supporting components were analyzed and chosen.In the end the high-pressure fuel pump from Scania’s XPI fuel system were chosen as well asa pressure transducer in the HP1000 series from ESI. Within the time frame of this thesis, theproject did not end up getting finished to the degree planned, but due to time constraints werehalted before starting manufacturing of the system. Some minor component choices remained aswell as documentation such as drawings and finalizing the physical layout of the system remained.All information regarding the remaining work needed to finalize the project and deploying thesystem in the test cell were outlined and with more time, the fuel system should fulfill its purposeof allowing testing and research of compression ignited fuel to be possible in the test cell.

  • 143.
    Gramner, Alexander
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Utveckling av ingångsinterface till tändstyrenheter för naturgas- och biogasmotorer2013Independent thesis Basic level (professional degree), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    SEM AB utvecklar och tillverkar tändstyrenheter för förbränningsmotorer, bland annat naturgas- och biogasmotorer. Tändstyrenheterna styr själva tändförloppet när de får en triggsignal från motorstyrsystemet (ECU). På grund av att enheterna används tillsammans med flera olika motorstyrsystem måste de anpassas for olika signaltyper och cylinderantal. Anpassningar av både mjukvaran och hårdvaran måste göras och detta kräver tid och resurser för utvecklarna på SEM.

    Syftet med detta arbete är att utveckla ett ingångsinterface till tändstyrenheterna som möjliggör att de kan anpassas på ett enklare sätt. För att minimera antalet komponenter i tändstyrenheterna ska även funktioner som realiseras med diskreta komponenter, om möjligt, integreras i ingångsinterfacet.

    En lämplig programmerbar krets för detta ändamål har valts. Valet blev en MAX V CPLD (Complex Programmable Logic Device) från Altera. Ingångsinterfacets funktioner har skapats i form av programkod i Verilog. Slutligen har simuleringar av programmet gjorts och dess funktion har verifierats med hjälp av ett utvecklingskort.

  • 144.
    Gregorcic, Bor
    et al.
    Uppsala University.
    Haglund, Jesper
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Conceptual Blending as an Interpretive Lens for Student Engagement with Technology: Exploring Celestial Motion on an Interactive Whiteboard2018Inngår i: Research in science education, ISSN 0157-244X, E-ISSN 1573-1898, s. 1-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present and analyze video data of upper secondary school students’ engagement with a computer-supported collaborative learning environment that enables them to explore astronomical phenomena (Keplerian motion). The students’ activities have an immersive and exploratory character, as students engage in open-ended inquiry and interact physically with the virtual environment displayed on an interactive whiteboard. The interplay of students’ playful exploration through physical engagement with the simulation environment, their attention to physics concepts and laws, and knowledge about the real planets orbiting the Sun presents an analytical challenge for the researcher and instructor encountering such complex learning environments. We argue that the framework of conceptual blending is particularly apt for dealing with the learning environment at hand, because it allows us to take into account the many diverse mental inputs that seem to shape the student activities described in the paper. We show how conceptual blending can be brought together with theoretical ideas concerned with embodied cognition and epistemology of physics, in order to provide researchers and instructors with a powerful lens for looking critically at immersive technology-supported learning environments. 

  • 145.
    Gustafsson, Marcus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Thermal Contributions and Balances in Flatness Measuring Roll: Modelling of Thermal Balances and Convective Heat Transfer Using CFD2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Devices for measurement of flatness in rolling mills is important to ensure high quality products and fewer strip breaks. One of these devices take the form of a measuring roll, which the strip is guided over after it has exited the reduction stage in the mill. The roll is traditionally used in cold rolling applications, and a desire to move to hot rolling introduces demands for research into the thermal balances that develops under operation. This report aims to create an overview into some of the contributions that make up the thermal balance, namely external convection and friction losses in bearings. Other contributions have been investigated by C. Karlsson (Master of Science thesis, Karlstad University, 2018). The heat transfer coefficients obtained for external convection proved to be too small to sustain reasonable temperatures under operation, if no type of cooling apparatus is utilized. Even with external cooling using pressurized air, the convective heat dissipation is too low, due to efficient strip-to-roll conduction. From the modelling performed in this report, friction losses from bearings can be considered as negligible. A model for describing the thermal balances using Newton’s law of cooling was developed, and related to steady state operating conditions by the use of a correction factor. The factor was obtained by comparing the cooling law with the results of a more precise numerical model. The studies in this project elucidate the critical aspects of the thermal balances and provides a basis for further, more detailed modelling.

  • 146.
    Gustafsson, Peter
    et al.
    Malardalen Univ, Sch Educ Culture & Commun, Vasteras, Sweden..
    Jonsson, Gunnar
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Enghag, Margareta
    Stockholm Univ, Math & Sci Educ, S-10691 Stockholm, Sweden.
    The problem-solving process in physics as observed when engineering students at university level work in groups2015Inngår i: European Journal of Engineering Education, ISSN 0304-3797, E-ISSN 1469-5898, Vol. 40, nr 4, s. 380-399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The problem-solving process is investigated for five groups of students when solving context-rich problems in an introductory physics course included in an engineering programme. Through transcripts of their conversation, the paths in the problem-solving process have been traced and related to a general problem-solving model. All groups exhibit backward moves to earlier stages in the problem-solving process. These earlier stages are revisited by the groups for identifying sub-problems, setting parameter values or even restating the goal. We interpret this action as coming from the fact that the students have not yet developed a knowledge base and a problem-solving scheme. Connected to the backward moves in the process are opportunities for the group members to build such a knowledge base from contributions and experiences from all group members. Problem contents that induce such moves are identified and can thus be considered by science teachers when constructing problems for group work.

  • 147.
    Gustavsson, Christer
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Nilsson, Lars
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Co-production of pyrolysis oil in district heating plants: Systems analysis of dual fluidized-bed pyrolysis with sequential vapor condensation2013Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 9, s. 5313-5319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Flash pyrolysis of biomass yields a liquid applicable as a fuel oil substitute and as a basis for production of chemicals and fuels. Biomass, being a renewable resource, is foreseen to be in increasing demand. An increased usage may lead to scarcity of biomass and emphasizes the need for high-efficiency conversion processes. In this study, the efficiency and capacity aspects of an integration of pyrolysis oil production with a district heating plant by means of dual fluidized-bed technology has been modeled. Further, fractional condensation of the pyrolysis vapors has been applied, enabling part of the condensation energy to be recovered. The concept shows potential for significant pyrolysis oil production while keeping the delivered power and heat constant. The use of excess heat from the pyrolysis production in the district heating net results in a 10% higher overall efficiency than production without heat supply to the district heating net.

  • 148.
    Gåård, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Damage mechanisms for tools used in applications subjected to combined impact and wear2017Konferansepaper (Fagfellevurdert)
  • 149.
    Gåård, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Damage mechanisms for tools used in applications subjected to combined wear and impact2017Konferansepaper (Fagfellevurdert)
  • 150.
    Gåård, Anders
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Early stages of tool damage in sheet metal forming2013Konferansepaper (Fagfellevurdert)
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