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  • Fransson, Beatrice
    et al.
    Linköping University, Department of Social and Welfare Studies, Social Work.
    Johanna, Karlsson
    Linköping University, Department of Social and Welfare Studies, Social Work.
    Inte på undantag: Hur föräldrar till barn med intellektuell funktionsnedsättning beskriver sina barns fritid med fokus på meningsfullhet och delaktighet2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I följande studie har tio föräldrar som har barn med intellektuell funktionsnedsättning intervjuats för att undersöka hur föräldrarna beskriver sina barns fritid med fokus på meningsfullhet och delaktighet. Föräldrarna är boende i olika stora kommuner och barnen är i olika åldrar. Metoden består av semistrukturerade intervjuer som spelats in och transkriberats. Materialet från intervjuerna har sammanställts och analyserats genom innehållsanalys. Resultatet har presenterats och delats in i sex olika kategorier.  Socialkonstruktivism och delaktighet är den teori och det begrepp som använts för att tolka och förstå resultatet. Berger och Luckmanns begrepp roller, den signifikanta andra, commonsense-kunskap, face-to-face-interaktion och institutioner samt Harts Delaktighetens stege använde vi oss framför allt av. Av intervjuerna framgick att föräldrarna upplever att fritidsaktivitetsutbudet är för litet och särskilt för barnen som är bosatta i en mindre kommun och att delaktighet och meningsfullhet är viktiga komponenter i fritiden. 

  • Guerrero-Bosagna, Carlos
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Epigenetics, evolution and the survival of the non-unfit2017In: The Biochemist, ISSN 0954-982X, Vol. 39, no 5, 8-11 p.Article in journal (Other academic)
    Abstract [en]

    The transition that occurred in vertebrates moving from water to land was a major step in the evolution of terrestrial animals. This is an evolutionary step that has always fascinated scientists and the general public. The land-to-water vertebrate transition happened around the Devonian period and involved structural changes such as the transition from fin to limb, a reduction of the gill arch, loss of the mid-fin and a reduction in the number of scales, among others. I will use this interesting example to depict how the same evolutionary process can be seen through two different lenses. One view, which is the most widespread way of seeing evolution, is the 'survival of the fittest'. The other is intentionally stated in the title as the double negative 'survival of the non-unfit'. Only semantic differences? Not in my view.

  • Public defence: 2017-12-12 13:15 Ada Lovelace,, Linköping
    Linders, Viktor
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Error analysis of summation-by-parts formulations: Dispersion, transmission and accuracy2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis we consider errors arising from finite difference operators on summation-by-parts (SBP) form, used in the discretisation of partial differential equations. The SBP operators are augmented with simultaneous-approximation-terms (SATs) to weakly impose boundary conditions. The SBP-SAT framework combines high order of accuracy with a systematic construction of provably stable boundary procedures, which renders it suitable for a wide range of problems.

    The first part of the thesis treats wave propagation problems discretised using SBP operators on coarse grids. Unless special care is taken, inaccurate approximations of the underlying dispersion relation materialises in the form of an incorrect propagation speed. We present a procedure for constructing SBP operators with minimal dispersion error. Experiments indicate that they outperform higher order non-optimal SBP operators for flow problems involving high frequencies and long simulation times.

    In the second part of the thesis, the formal order of accuracy of SBP operators near boundaries is analysed. We prove that the order in the interior of a diagonal norm based SBP operator must be at least twice that of the boundary stencil, irrespective of the grid point distribution near the boundary. This generalises the classical theory posed on uniform and conforming grids. We further show that for a common class of SBP operators, the diagonal norm defines a quadrature rule of the same order as the interior stencil. Again, this result is independent of the grid.

    In the final contribution if the thesis, we introduce the notion of a transmission problem to describe a general class of problems where different dynamics are coupled in time. Well-posedness and stability analyses are performed for continuous and discrete problems. A general condition is obtained that is necessary and sufficient for the transmission problem to satisfy an energy estimate. The theory provides insights into the coupling of fluid flow models, multi-block formulations, numerical filters, interpolation and multi-grid implementations.

    List of papers
    1. Uniformly Best Wavenumber Approximations by Spatial Central Difference Operators
    Open this publication in new window or tab >>Uniformly Best Wavenumber Approximations by Spatial Central Difference Operators
    2015 (English)In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 300, 695-709 p.Article in journal (Refereed) Published
    Abstract [en]

    We construct accurate central difference stencils for problems involving high frequency waves or multi-frequency solutions over long time intervals with a relatively coarse spatial mesh, and with an easily obtained bound on the dispersion error. This is done by demonstrating that the problem of constructing central difference stencils that have minimal dispersion error in the infinity norm can be recast into a problem of approximating a continuous function from a finite dimensional subspace with a basis forming a Chebyshev set. In this new formulation, characterising and numerically obtaining optimised schemes can be done using established theory.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Dispersion relation; Wave propagation; Wavenumber approximation; Finite differences; Approximation theory
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-120896 (URN)10.1016/j.jcp.2015.08.005 (DOI)000361573200035 ()
    Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2017-11-20Bibliographically approved
    2. A simple and efficient incompressible Navier-Stokes solver for unsteady complex geometry flows on truncated domains
    Open this publication in new window or tab >>A simple and efficient incompressible Navier-Stokes solver for unsteady complex geometry flows on truncated domains
    Show others...
    2017 (English)In: Computers & Fluids, ISSN 0045-7930, E-ISSN 1879-0747, Vol. 150, 84-94 p.Article in journal (Refereed) Published
    Abstract [en]

    Incompressible Navier-Stokes solvers based on the projection method often require an expensive numerical solution of a Poisson equation for a pressure-like variable. This often involves linear system solvers based on iterative and multigrid methods which may limit the ability to scale to large numbers of processors. The artificial compressibility method (ACM) [6] introduces a time derivative of the pressure into the incompressible form of the continuity equation creating a coupled closed hyperbolic system that does not require a Poisson equation solution and allows for explicit time-marching and localized stencil numerical methods. Such a scheme should theoretically scale well on large numbers of CPUs, GPU'€™s, or hybrid CPU-GPU architectures. The original ACM was only valid for steady flows and dual-time stepping was often used for time-accurate simulations. Recently, Clausen [7] has proposed the entropically damped artificial compressibility (EDAC) method which is applicable to both steady and unsteady flows without the need for dual-time stepping. The EDAC scheme was successfully tested with both a finite-difference MacCormack'€™s method for the two-dimensional lid driven cavity and periodic double shear layer problem and a finite-element method for flow over a square cylinder, with scaling studies on the latter to large numbers of processors. In this study, we discretize the EDAC formulation with a new optimized high-order centered finite-difference scheme and an explicit fourth-order Runge-€“Kutta method. This is combined with an immersed boundary method to efficiently treat complex geometries and a new robust outflow boundary condition to enable higher Reynolds number simulations on truncated domains. Validation studies for the Taylor-€“Green Vortex problem and the lid driven cavity problem in both 2D and 3D are presented. An eddy viscosity subgrid-scale model is used to enable large eddy simulations for the 3D cases. Finally, an application to flow over a sphere is presented to highlight the boundary condition and performance comparisons to a traditional incompressible Navier-€“Stokes solver is shown for the 3D lid driven cavity. Overall, the combined EDAC formulation and discretization is shown to be both effective and affordable.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keyword
    Artificial compressibility method, EDAC, High-order numerical methods, Large Eddy simulation
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-136507 (URN)10.1016/j.compfluid.2017.03.030 (DOI)000401219000007 ()
    Note

    Funding agencies: Rosenblatt Chair within the faculty of Mechanical Engineering; Zeff Fellowship Trust

    Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-11-20Bibliographically approved
    3. Summation-by-Parts Operators with Minimal Dispersion Error for Coarse Grid Flow Calculations
    Open this publication in new window or tab >>Summation-by-Parts Operators with Minimal Dispersion Error for Coarse Grid Flow Calculations
    2017 (English)In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 340, 34 p.160-176 p.Article in journal (Refereed) Published
    Abstract [en]

    We present a procedure for constructing Summation-by-Parts operators with minimal dispersion error both near and far from numerical interfaces. Examples of such operators are constructed and compared with a higher order non-optimised Summation-by-Parts operator. Experiments show that the optimised operators are superior for wave propagation and turbulent flows involving large wavenumbers, long solution times and large ranges of resolution scales.

    Place, publisher, year, edition, pages
    Elsevier, 2017. 34 p.
    Keyword
    Summation-by-Parts, Dispersion relation, Finite differences, Wave Propagation
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-136474 (URN)10.1016/j.jcp.2017.03.039 (DOI)000401137900009 ()
    Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2017-11-20Bibliographically approved
    4. On the order of Accuracy of Finite Difference Operators on Diagonal Norm Based Summation-By-Parts Form
    Open this publication in new window or tab >>On the order of Accuracy of Finite Difference Operators on Diagonal Norm Based Summation-By-Parts Form
    2017 (English)Report (Other academic)
    Abstract [en]

    In this paper we generalise results regarding the order of accuracy of finite difference operators on Summation-By-Parts (SBP) form, previously known to hold on uniform grids, to grids with arbitrary point distributions near domain boundaries. We give a definite proof that the order of accuracy in the interior of a diagonal norm based SBP operator must be at least twice that of the boundary stencil, irrespective of the grid point distribution near the boundary. Additionally, we prove that if the order of accuracy in the interior is precisely twice that of the boundary, then the diagonal norm defines a quadrature rule of the same order as the interior stencil. Again, this result is independent of the grid point distribution near the domain boundaries.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017. 15 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 2017:11
    Keyword
    Finite difference schemes, summation-by-parts operators, numerical differentiation, quadrature rules, order of accuracy
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-140815 (URN)
    Available from: 2017-09-12 Created: 2017-09-12 Last updated: 2017-11-20Bibliographically approved
    5. Well-posed and Stable Transmission Problems
    Open this publication in new window or tab >>Well-posed and Stable Transmission Problems
    2017 (English)Report (Other academic)
    Abstract [en]

    We introduce the notion of a transmission problem to describe a general class of problems where different dynamics are coupled in time. Well-posedness and stability is analysed for continuous and discrete problems using both strong and weak formulations, and a general transmission condition is obtained. The theory is applied to several examples including the coupling of fluid flow models, multi-grid implementations, multi-block formulations and numerical filtering.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017. 28 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 15
    Keyword
    Initial-boundary value problems, Transmission problems, Energy estimates, Well-posedness, Multi-block, Numerical Filter. Interpolation, Multi-grid, Summation-by-Parts, Stability
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-142348 (URN)LiTH-MAT-R--2017/15--SE (ISRN)
    Available from: 2017-10-27 Created: 2017-10-27 Last updated: 2017-11-20Bibliographically approved
  • Public defence: 2017-12-15 10:15 A35, A-huset, Linköping
    Busse, Christian
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Aspects of Crack Growth in Single-Crystal Nickel-Base Superalloys2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Licentiate of Engineering thesis is a product of the results generated in the research project KME-702, which comprises modelling, microstructure investigations and material testing of cast nickel-base superalloys.

    The main objective of this work is to model the fatigue crack propagation behaviour in single-crystal nickel-base superalloys. To achieve this, the influence of the crystal orientations on the cracking behaviour is assessed. The results show that the crystal orientation is strongly affecting the material response and must be accounted for. Furthermore, a linear elastic crack driving force parameter suitable for describing crystallographic cracking has been developed. This parameter is based on resolved anisotropic stress intensity factors and is able to predict the correct crystallographic cracking plane after a transition from a Mode I crack. Finally, a method to account for inelastic deformations in a linear elastic fracture mechanics context was investigated. A residual stress field is extracted from an uncracked finite-element model with a perfectly plastic material model and superimposed on the stress field from the cracked model with a linear elastic material model to account for the inelastic deformations during the determination of the crack driving force. The modelling work is validated by material testing on two different specimen geometries at different temperatures.

    This Licentiate of Engineering thesis consists of two parts, where Part I gives an introduction and background to the research area, while Part II consists of three papers.

    List of papers
    1. A FINITE ELEMENT STUDY OF THE EFFECT OF CRYSTAL ORIENTATION AND MISALIGNMENT ON THE CRACK DRIVING FORCE IN A SINGLE-CRYSTAL SUPERALLOY
    Open this publication in new window or tab >>A FINITE ELEMENT STUDY OF THE EFFECT OF CRYSTAL ORIENTATION AND MISALIGNMENT ON THE CRACK DRIVING FORCE IN A SINGLE-CRYSTAL SUPERALLOY
    Show others...
    2016 (English)In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 7A, AMER SOC MECHANICAL ENGINEERS , 2016, no UNSP V07AT28A002Conference paper, Published paper (Refereed)
    Abstract [en]

    The elastic and plastic anisotropy of the single-crystal materials bring many difficulties in terms of modeling, evaluation and prediction of fatigue crack growth. In this paper a single-crystal material model has been adopted to a finite element-environment, which is paired with a crack growth tool. All simulations are performed in a three-dimensional context. This methodology makes it possible to analyze complex finite element-models, which are more application-near than traditional two-dimensional models. The influence of the crystal orientation, as well as the influence of misalignments of the crystal orientation due to the casting process are investigated. It is shown that both the crystal orientation and the misalignment from the ideal crystal orientation are important for the crack driving force. The realistic maximum limit of 10 degrees misalignment is considered. It can be seen that crack growth behavior is highly influenced by the misalignment. This knowledge is of great interest for the industry in order to evaluate the crack growth in single-crystal components more accurately.

    Place, publisher, year, edition, pages
    AMER SOC MECHANICAL ENGINEERS, 2016
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-132570 (URN)10.1115/GT2016-56305 (DOI)000385461600011 ()978-0-7918-4983-5 (ISBN)
    Conference
    ASME Turbo Expo: Turbine Technical Conference and Exposition
    Available from: 2016-11-14 Created: 2016-11-14 Last updated: 2017-11-20
    2. Three-Dimensional LEFM Prediction of Fatigue Crack Propagation in a Gas Turbine Disk Material at Component Near Conditions
    Open this publication in new window or tab >>Three-Dimensional LEFM Prediction of Fatigue Crack Propagation in a Gas Turbine Disk Material at Component Near Conditions
    Show others...
    2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 4, 042506Article in journal (Refereed) Published
    Abstract [en]

    In this paper, the possibility to use linear elastic fracture mechanics (LEFM), with and without a superimposed residual stress field, to predict fatigue crack propagation in the gas turbine disk material Inconel 718 has been studied. A temperature of 400 degrees C and applied strain ranges corresponding to component near conditions have been considered. A three-dimensional crack propagation software was used for determining the stress intensity factors (SIFs) along the crack path. In the first approach, a linear elastic material behavior was used when analyzing the material response. The second approach extracts the residual stresses from an uncracked model with perfectly plastic material behavior after one loading cycle. As a benchmark, the investigated methods are compared to experimental tests, where the cyclic lifetimes were calculated by an integration of Paris law. When comparing the results, it can be concluded that the investigated approaches give good results, at least for longer cracks, even though plastic flow was taking place in the specimen. The pure linear elastic simulation overestimates the crack growth for all crack lengths and gives conservative results over all considered crack lengths. Noteworthy with this work is that the 3D-crack propagation could be predicted with the two considered methods in an LEFM context, although plastic flow was present in the specimens during the experiments.

    Place, publisher, year, edition, pages
    ASME, 2016
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-126240 (URN)10.1115/1.4031526 (DOI)000371125800020 ()
    Note

    Funding Agencies|Siemens Industrial Turbomachinery AB through Research Consortium of Materials Technology for Thermal Energy Processes [KME-702]; Swedish Energy Agency

    Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-11-20
  • Public defence: 2017-12-15 13:00 Schrödinger, E324, Fysikhuset, Linköping
    Løtvedt, Pia Katrine
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Domestication and early experiences in chickens: Behavior, stress and gene expression2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    A number of animal species have undergone domestication, the process of becoming adapted to living in captivity and in proximity to humans. Common for these species is that they have all developed certain traits, including changes to coat color, body size and level of fearfulness. This has been termed the domestic phenotype. Among these traits is also an attenuation of the response to stress, both behaviorally and physiologically. Thus, release of glucocorticoids such as cortisol or corticosterone is lower in domesticated species. However, the underlying mechanism for this is not yet well understood. In this thesis, we have investigated genetic mechanisms for the attenuation of the physiological stress response in ancestral chickens, the Red Junglefowl, and domesticated chickens, the White Leghorn.

    We found a number of genes that differed in expression between the two breeds in several tissues involved in the stress response. Among the most interesting findings were lower expression of genes involved in production and secretion of ACTH in the pituitary, and in the production of glucocorticoids in the adrenal glands, in the domesticated White Leghorns. We also found higher expression of the glucocorticoid receptor in White Leghorns, indicating that they may have a more efficient negative feedback of the physiological stress response.

    We then investigated the transcriptome of the chicken pituitary more closely, and we discovered that a number of genes highly involved in several important physiological axes showed differential expression between the ancestral and the domesticated breed. Among these were genes involved in the stress response, the reproductive system, and in metabolism and growth. As these traits are modified in domesticated species, our results suggest that changes to gene expression in the pituitary may be an important underlying factor of the domestic phenotype.

    A separate aim of this thesis was to investigate effects of hatching time in chickens on their subsequent phenotype. Time of hatching constitutes an early experience that may differ between individuals, and we therefore hypothesized that differences in hatching time would affect chickens later in life. While a number of studies have been performed on hatching time and post-hatch growth, very little work has been done on effects on behavior. We found that the time of hatching had sex-specific effects. Hatching times in females were negatively correlated with body weight, whereas in males, behaviors such as reaction to novelty and spatial learning were affected.

    As time of hatching is governed by various hormones, including thyroid hormone and corticosterone, we suggest that changes to the levels of these hormones could affect both hatching time and post-hatch phenotypes. Understanding these mechanisms better would be beneficial in terms of production, where batch homogeneity is important, in research on early experiences and the potential for maternal programming, and in evolutionary questions on trade-off between different life strategies.

    List of papers
    1. Chicken domestication changes expression of stress-related genes in brain, pituitary and adrenals.
    Open this publication in new window or tab >>Chicken domestication changes expression of stress-related genes in brain, pituitary and adrenals.
    Show others...
    2017 (English)In: Neurobiology of stress, ISSN 2352-2895, Vol. 7, 113-121 p.Article in journal (Refereed) Published
    Abstract [en]

    Domesticated species have an attenuated behavioral and physiological stress response compared to their wild counterparts, but the genetic mechanisms underlying this change are not fully understood. We investigated gene expression of a panel of stress response-related genes in five tissues known for their involvement in the stress response: hippocampus, hypothalamus, pituitary, adrenal glands and liver of domesticated White Leghorn chickens and compared it with the wild ancestor of all domesticated breeds, the Red Junglefowl. Gene expression was measured both at baseline and after 45 min of restraint stress. Most of the changes in gene expression related to stress were similar to mammals, with an upregulation of genes such as FKBP5, C-FOS and EGR1 in hippocampus and hypothalamus and StAR, MC2R and TH in adrenal glands. We also found a decrease in the expression of CRHR1 in the pituitary of chickens after stress, which could be involved in negative feedback regulation of the stress response. Furthermore, we observed a downregulation of EGR1 and C-FOS in the pituitary following stress, which could be a potential link between stress and its effects on reproduction and growth in chickens. We also found changes in the expression of important genes between breeds such as GR in the hypothalamus, POMC and PC1 in the pituitary and CYP11A1 and HSD3B2 in the adrenal glands. These results suggest that the domesticated White Leghorn may have a higher capacity for negative feedback of the HPA axis, a lower capacity for synthesis of ACTH in the pituitary and a reduced synthesis rate of corticosterone in the adrenal glands compared to Red Junglefowl. All of these findings could explain the attenuated stress response in the domesticated birds.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keyword
    Animal domestication, Chicken, Gene expression, Glucocorticoid receptor, HPA axis, Stress response
    National Category
    Genetics
    Identifiers
    urn:nbn:se:liu:diva-143054 (URN)10.1016/j.ynstr.2017.08.002 (DOI)28879214 (PubMedID)
    Available from: 2017-11-17 Created: 2017-11-17 Last updated: 2017-11-17
    2. Effects of Hatching Time on Behavior and Weight Development of Chickens
    Open this publication in new window or tab >>Effects of Hatching Time on Behavior and Weight Development of Chickens
    2014 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 9, no 7, e103040- p.Article in journal (Refereed) Published
    Abstract [en]

    The length of the embryonic period varies both among and within species and can affect the individual phenotype in many ways, both physiologically and behaviorally. In chickens, the hatch window may last 24-48 hours (up to 10% of the incubation time), and studies have shown that incubation length may affect post-hatch growth and physiology. However, little is known about effects on behavior. We therefore investigated how behavior variation correlates with hatching time in the early life of chickens. We also measured egg weight and egg weight loss in relation to hatching time, as well as post-hatch growth. For females, there was a negative correlation between hatch time and body weight from day 4 and throughout the experiment. For males, such a correlation was only observed when testing all hatched males up until day 10. The birds were exposed to a number of behavioral tests, and a principal components analysis was performed on the variables, resulting in four components. For the largest component, termed "Passivity, a tendency of a difference was found between early and middle male hatchers. Furthermore, a significant difference between early and middle male hatchers was found in the second component, termed "Response to novelty. In a spatial learning test, late hatchers tended to learn slower. The behavior of females was not significantly affected by hatching time in any of these tests. This study is among the first to demonstrate a link between time of hatching and early behavior in a precocial species like the chicken, and may help shedding light on the evolutionary trade-offs between incubation length and post-hatch traits. The results may also be relevant from a perspective of stress coping and therefore also for animal welfare and productivity in the chicken industry. The mechanisms linking hatching time with post-hatch phenotype remain to be investigated.

    Place, publisher, year, edition, pages
    Public Library of Science, 2014
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-111296 (URN)10.1371/journal.pone.0103040 (DOI)000341354800055 ()25058654 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas); European Research Council

    Available from: 2014-10-14 Created: 2014-10-14 Last updated: 2017-11-17
  • Løtvedt, Pia Katrine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Fallahsharoudi, Amir
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bektic, Lejla
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Chicken domestication changes expression of stress-related genes in brain, pituitary and adrenals.2017In: Neurobiology of stress, ISSN 2352-2895, Vol. 7, 113-121 p.Article in journal (Refereed)
    Abstract [en]

    Domesticated species have an attenuated behavioral and physiological stress response compared to their wild counterparts, but the genetic mechanisms underlying this change are not fully understood. We investigated gene expression of a panel of stress response-related genes in five tissues known for their involvement in the stress response: hippocampus, hypothalamus, pituitary, adrenal glands and liver of domesticated White Leghorn chickens and compared it with the wild ancestor of all domesticated breeds, the Red Junglefowl. Gene expression was measured both at baseline and after 45 min of restraint stress. Most of the changes in gene expression related to stress were similar to mammals, with an upregulation of genes such as FKBP5, C-FOS and EGR1 in hippocampus and hypothalamus and StAR, MC2R and TH in adrenal glands. We also found a decrease in the expression of CRHR1 in the pituitary of chickens after stress, which could be involved in negative feedback regulation of the stress response. Furthermore, we observed a downregulation of EGR1 and C-FOS in the pituitary following stress, which could be a potential link between stress and its effects on reproduction and growth in chickens. We also found changes in the expression of important genes between breeds such as GR in the hypothalamus, POMC and PC1 in the pituitary and CYP11A1 and HSD3B2 in the adrenal glands. These results suggest that the domesticated White Leghorn may have a higher capacity for negative feedback of the HPA axis, a lower capacity for synthesis of ACTH in the pituitary and a reduced synthesis rate of corticosterone in the adrenal glands compared to Red Junglefowl. All of these findings could explain the attenuated stress response in the domesticated birds.

  • Olsson, Jonas
    Linköping University, Department of Management and Engineering, Logistics & Quality Management.
    Tidsdriven ABC-kalkylering inom tredjepartslogistik: Tillämpningar för att driva produktivitet hos PostNord Logistics TPL i Norrköping2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    PostNord Logistics TPL AB (PostNord) is one of the largest third-party logistics providers in the Nordics. At the tire warehouse in Norrköping, PostNord performs logistics activities within inbound, storage, production and outbound for several retailers/distributors. Labor is by far the largest cost and hence the management focuses on productivity, for example by efficiency and improving precision in workforce management. The purpose of this study was therefore to develop a cost model based on Time-Driven Activity-Based Costing (TDABC) for the warehouse operations, which can be applied to support PostNord’s efforts to drive productivity. TDABC is a methodology to estimate the consumption of resources such as personnel and equipment caused by different transactions, products or customers. By modelling activities in time equations which are based on time estimates it is possible to show what impacts time consumption (man-hours required).

    Time equations for the three activities assembly, receiving and putaway were developed. The approach included verifying and processing data, regression analyses, time studies, interviews, observations and finalization and validation of the cost models in Excel. The finalized models proved to be reasonable and to offer promising precision day-to-day. Next, four user interfaces were developed; what-if analyses for assembly, receiving and putaway as well as staff scheduling for assembly. Via usability tests inspired by the think-aloud method it was shown that the applications were usable and expected to support the efforts to drive productivity by efficiency and precision in staffing.

    In the literature, there is an articulated need for further studies of the TDABC methodology, including the design process for TDABC and specifically the development of time estimates for the time equations. This study contributes to the methodology in the following four ways. 1) An overall method (process) for TDABC which future studies may utilize. 2) Learnings about specific aspects of the overall method regarding interviews, verifying and processing data, as well as the use of regression analysis and time study. 3) Examples of characteristics of the finalized cost models and implications of them. 4) Guidance regarding important choices for the modelling of time equations and implications of them.

  • Nilsson, Oscar
    Linköping University, Department of Management and Engineering, Solid Mechanics.
    Experimental Procedures for Operational Modal Analysis of a Power Pack on a Drill Rig2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    All structures have modal properties such as natural frequencies and damping. In engineeringit is often of interest to estimate these modal properties for certain structures, to be used whenmodelling for example fatigue. This is done by computing them from finite element models, by using experimental measurements or both. In the case of doing both, a finite elementmodel is usually established first and adjusted to fit measurements from experiments.

    Atlas Copco Rock Drills AB is the company where this thesis has been performed and the subject is experimental procedures related to estimating modal properties of the so calledpower pack, which essentially is a modularised engine and hydraulic power source of an Atlas Copco drill rig. Their current method for estimating these properties is a classical procedure which makes use of an impact hammer that an operator strikes the power pack with to induce excitation. Due to concealment of behind other parts the power pack when mounted inside the drill rig, the number of places where the operator is able to strike the power pack in is limited. Another problem with the current procedure is that it can be difficult to strike the power pack with a strong enough impulse to generate reliable results.

    In this thesis a new experimental procedure for Atlas Copco to use is suggested. It is based on operational modal analysis (OMA), which uses the machinery's excitation from its operational conditions to compute modal estimates. A comparison between different experimental procedures have been done and the suggested procedure is the following: excitation by engine sweep; modal identifcation by the PolyMAX method and mode shape scaling by the harmonic scaling method. An experiment was performed to compare two OMA procedures.The suggested procedure is the one that generated the better results of the two.

  • Samuelsson, MiaMaria
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Gustafsson, Isabella
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Minskade Upplysningskrav: En kostnadsbesparing ur ett företagsperspektiv?2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Thesis problem: On January 1st, 2016, the Annual Accounts Act (SFS 1995: 1554) was updated in order to simplify the accounting work in smaller companies. The update implies – amongst other things – reduced disclosure requirements for smaller companies. According to the legislative history, previous accounting requirements were very burdensome, in particular for micro-enterprises. A decreased disclosure obligation aims to reduce the administrative costs in micro-enterprises in order to make the costs proportionate to its usefulness. Annual reports provide an important basis for decision making in order to enable informed decisions for micro- enterprises stakeholders, especially lenders. Annual report information, however, is costly to achieve and it is crucial to find a balance between its costs and usefulness.

    Aim: The study aims to investigate the effects of reduced disclosure requirements for micro- enterprises and whether these have been introduced at the expense of the usefulness the annual reports should give the stakeholders.

    Method: The study has been conducted based on a qualitative strategy with a deductible approach. The investigation has been accomplished through interviews with lenders and accounting consultants of micro-enterprises.

    Conclusions: The study's result shows that the practical accounting work is not identical to how it is described in theory and in legislative history. The study's respondents have testified about no, or small savings potential for micro-enterprises based on reduced disclosure requirements. However, they confirm that some implementation costs have arisen. As far as the interest group lenders are concerned, the study indicates that the usefulness of micro- enterprises' annual reports after the law modification are quite unchanged.

    Contribution: The study has contributed to raising awareness of how the new simplification rules for micro-enterprises have been implemented and what impact they have amongst concerned groups.

  • Rosander, Oscar
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Borta, Elena
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Leadership in Multicultural Teams: Impact of Highly Educated & Multicultural Creative Teams on Leadership2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With a rapidly changing work environment due to increased migration and ease of travel, organisations today is challenged by a multicultural setting of individuals in employment. Additionally there is an increase in the number of highly educated employees working in the same teams as lesser educated individuals. The purpose of this paper is to research how the leadership is influenced by the cultural and educational diversity in a team. The study is a comparison study between two demographically similar teams in the same organisation. The difference between teams is that one team comprises of highly educated individuals classified under creative class based on Richard Florida's (2002) workforce classification. The other team comprises of individuals with lower education and are classified under service class. This research has found that the leadership is influenced in a different way when the level of education is included in the multicultural teams. Thus, besides culture, education also plays a big part in how the leadership is impacted. 

  • Degelder, Francois
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Melbye, Robert
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Competence Development: What can project-based organizations learn from the management of a hockey team?2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Project-based organizations (PBOs) have drawn attention in business management and represent an increasingly important part of organizations. If managing by projects represents an adapted way to cope with the current environment, it also comes with new challenges. This research brings light on the organizational tensions between immediate performance and sustained performance in PBOs by focusing on competence development as the crucial means to achieve sustained performance. Because PBOs are temporary by nature, competence development represents one of their challenges. Therefore, this research was conducted to gain a better understanding of how this tradeoff can be managed by PBOs.

    With that purpose, we both researched how this organizational tradeoff and competence development processes were managed in a hockey organization. In sport organizations, player succession is crucial to the organization’s overall performance and survival, therefore making competence development a key activity. The research led us to grasp a better understanding of the nature of the tradeoff between immediate performance and sustained performance as well as brought additional findings on competence development processes. More specifically, it was found that this tradeoff requires adaptation to project stages. We summarized and visualized the findings by providing a framework that can act as a tool for practitioners in PBOs to understand and therefore manage the tradeoff between immediate performance and sustained performance by implementing competence development.  

  • Public defence: 2017-12-14 10:15 ACAS, A-huset, Linköping
    Posadzy, Kinga
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Social and Economic Factors in Decision Making under Uncertainty: Five Essays in Behavioral Economics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis is to improve the understanding of human behavior that goes beyond monetary rewards. In particular, it investigates social influences in individual’s decision making in situations that involve coordination, competition, and deciding for others. Further, it compares how monetary and social outcomes are perceived. The common theme of all studies is uncertainty. The first four essays study individual decisions that have uncertain consequences, be it due to the actions of others or chance. The last essay, in turn, uses the advances in research on decision making under uncertainty to predict behavior in riskless choices.

    The first essay, Fairness Versus Efficiency: How Procedural Fairness Concerns Affect Coordination, investigates whether preferences for fair rules undermine the efficiency of coordination mechanisms that put some individuals at a disadvantage. The results from a laboratory experiment show that the existence of coordination mechanisms, such as action recommendations, increases efficiency, even if one party is strongly disadvantaged by the mechanism. Further, it is demonstrated that while individuals’ behavior does not depend on the fairness of the coordination mechanism, their beliefs about people’s behavior do.

    The second essay, Dishonesty and Competition. Evidence from a stiff competition environment, explores whether and how the possibility to behave dishonestly affects the willingness to compete and who the winner is in a competition between similarly skilled individuals. We do not find differences in competition entry between competitions in which dishonesty is possible and in which it is not. However, we find that due to the heterogeneity in propensity to behave dishonestly, around 20% of winners are not the best-performing individuals. This implies that the efficient allocation of resources cannot be ensured in a stiff competition in which behavior is unmonitored.

    The third essay, Tracing Risky Decision Making for Oneself and Others: The Role of Intuition and Deliberation, explores how individuals make choices under risk for themselves and on behalf of other people. The findings demonstrate that while there are no differences in preferences for taking risks when deciding for oneself  and for others, individuals have greater decision error when choosing for other individuals. The differences in the decision error can be partly attributed to the differences in information processing; individuals employ more deliberative cognitive processing when deciding for themselves than when deciding for others. Conducting more information processing when deciding for others is related to the reduction in decision error.

    The fourth essay, The Effect of Decision Fatigue on Surgeons’ Clinical Decision Making, investigates how mental depletion, caused by a long session of decision making, affects surgeon’s decision to operate. Exploiting a natural experiment, we find that surgeons are less likely to schedule an operation for patients who have appointment late during the work shift than for patients who have appointment at the beginning of the work shift. Understanding how the quality of medical decisions depends on when the patient is seen is important for achieving both efficiency and fairness in health care, where long shifts are popular.

    The fifth essay, Preferences for Outcome Editing in Monetary and Social Contexts, compares whether individuals use the same rules for mental representation of monetary outcomes (e.g., purchases, expenses) as for social outcomes (e.g., having nice time with friends). Outcome editing is an operation in mental accounting that determines whether individuals prefer to first combine multiple outcomes before their evaluation (integration) or evaluate each outcome separately (segregation). I find that the majority of individuals express different preferences for outcome editing in the monetary context than in the social context. Further, while the results on the editing of monetary outcomes are consistent with theoretical predictions, no existing model can explain the editing of social outcomes.

    List of papers
    1. Fairness versus efficiency: how procedural fairness concerns affect coordination
    Open this publication in new window or tab >>Fairness versus efficiency: how procedural fairness concerns affect coordination
    2017 (English)In: Experimental Economics, ISSN 1386-4157, E-ISSN 1573-6938Article in journal (Refereed) Published
    Abstract [en]

    We investigate in a laboratory experiment whether procedural fairness concerns affect how well individuals are able to solve a coordination problem in a two-player Volunteer’s Dilemma. Subjects receive external action recommendations, either to volunteer or to abstain from it, in order to facilitate coordination and improve efficiency. We manipulate the fairness of the recommendation procedure by varying the probabilities of receiving the disadvantageous recommendation to volunteer between players. We find evidence that while recommendations improve overall efficiency regardless of their implications for expected payoffs, there are behavioural asymmetries depending on the recommendation: advantageous recommendations are followed less frequently than disadvantageous ones and beliefs about others’ actions are more pessimistic in the treatment with recommendations inducing unequal expected payoffs.

    Place, publisher, year, edition, pages
    Springer, 2017
    Keyword
    Coordination, Correlated Equilibrium, Recommendations, Procedural fairness, Volunteer's Dilemma, Experiment
    National Category
    Economics
    Identifiers
    urn:nbn:se:liu:diva-140644 (URN)10.1007/s10683-017-9540-5 (DOI)
    Funder
    Swedish Research Council Formas
    Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-11-17Bibliographically approved
  • Public defence: 2017-12-13 09:00 Berzeliussalen, Linköping
    Blystad, Ida
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Clinical Applications of Synthetic MRI of the Brain2017Doctoral thesis, comprehensive summary (Other academic)
    List of papers
    1. Synthetic MRI of the brain in a clinical setting
    Open this publication in new window or tab >>Synthetic MRI of the brain in a clinical setting
    Show others...
    2012 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 53, no 10, 1158-1163 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND:

    Conventional magnetic resonance imaging (MRI) has relatively long scan times for routine examinations, and the signal intensity of the images is related to the specific MR scanner settings. Due to scanner imperfections and automatic optimizations, it is impossible to compare images in terms of absolute image intensity. Synthetic MRI, a method to generate conventional images based on MR quantification, potentially both decreases examination time and enables quantitative measurements.

    PURPOSE:

    To evaluate synthetic MRI of the brain in a clinical setting by assessment of the contrast, the contrast-to-noise ratio (CNR), and the diagnostic quality compared with conventional MR images.

    MATERIAL AND METHODS:

    Twenty-two patients had synthetic imaging added to their clinical MR examination. In each patient, 12 regions of interest were placed in the brain images to measure contrast and CNR. Furthermore, general image quality, probable diagnosis, and lesion conspicuity were investigated.

    RESULTS:

    Synthetic T1-weighted turbo spin echo and T2-weighted turbo spin echo images had higher contrast but also a higher level of noise, resulting in a similar CNR compared with conventional images. Synthetic T2-weighted FLAIR images had lower contrast and a higher level of noise, which led to a lower CNR. Synthetic images were generally assessed to be of inferior image quality, but agreed with the clinical diagnosis to the same extent as the conventional images. Lesion conspicuity was higher in the synthetic T1-weighted images, which also had a better agreement with the clinical diagnoses than the conventional T1-weighted images.

    CONCLUSION:

    Synthetic MR can potentially shorten the MR examination time. Even though the image quality is perceived to be inferior, synthetic images agreed with the clinical diagnosis to the same extent as the conventional images in this study.

    Place, publisher, year, edition, pages
    Sage Publications, 2012
    Keyword
    CNS, MR imaging, brain, technology assessment, imaging sequences
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-89641 (URN)10.1258/ar.2012.120195 (DOI)000314077400015 ()23024181 (PubMedID)
    Available from: 2013-02-28 Created: 2013-02-28 Last updated: 2017-11-16Bibliographically approved
    2. Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent
    Open this publication in new window or tab >>Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent
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    2016 (English)In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 37, no 1, 94-100 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND AND PURPOSE: Contrast-enhancing MS lesions are important markers of active inflammation in the diagnostic work-up of MS and in disease monitoring with MR imaging. Because intravenous contrast agents involve an expense and a potential risk of adverse events, it would be desirable to identify active lesions without using a contrast agent. The purpose of this study was to evaluate whether pre-contrast injection tissue-relaxation rates and proton density of MS lesions, by using a new quantitative MR imaging sequence, can identify active lesions. MATERIALS AND METHODS: Forty-four patients with a clinical suspicion of MS were studied. MR imaging with a standard clinical MS protocol and a quantitative MR imaging sequence was performed at inclusion (baseline) and after 1 year. ROIs were placed in MS lesions, classified as nonenhancing or enhancing. Longitudinal and transverse relaxation rates, as well as proton density were obtained from the quantitative MR imaging sequence. Statistical analyses of ROI values were performed by using a mixed linear model, logistic regression, and receiver operating characteristic analysis. RESULTS: Enhancing lesions had a significantly (P < .001) higher mean longitudinal relaxation rate (1.22 0.36 versus 0.89 +/- 0.24), a higher mean transverse relaxation rate (9.8 +/- 2.6 versus 7.4 +/- 1.9), and a lower mean proton density (77 +/- 11.2 versus 90 +/- 8.4) than nonenhancing lesions. An area under the receiver operating characteristic curve value of 0.832 was obtained. CONCLUSIONS: Contrast-enhancing MS lesions often have proton density and relaxation times that differ from those in nonenhancing lesions, with lower proton density and shorter relaxation times in enhancing lesions compared with nonenhancing lesions.

    Place, publisher, year, edition, pages
    AMER SOC NEURORADIOLOGY, 2016
    National Category
    Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-124482 (URN)10.3174/ajnr.A4501 (DOI)000367466500019 ()26471751 (PubMedID)
    Note

    Funding Agencies|National Science and Engineering Research Council; University of Linkoping; University Hospital Research Funds

    Available from: 2016-02-02 Created: 2016-02-01 Last updated: 2017-11-16
    3. Quantitative MRI for analysis of peritumoral edema in malignant gliomas
    Open this publication in new window or tab >>Quantitative MRI for analysis of peritumoral edema in malignant gliomas
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    2017 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 5, e0177135Article in journal (Refereed) Published
    Abstract [en]

    Background and purpose Damage to the blood-brain barrier with subsequent contrast enhancement is a hallmark of glioblastoma. Non-enhancing tumor invasion into the peritumoral edema is, however, not usually visible on conventional magnetic resonance imaging. New quantitative techniques using relaxometry offer additional information about tissue properties. The aim of this study was to evaluate longitudinal relaxation R-1, transverse relaxation R-2, and proton density in the peritumoral edema in a group of patients with malignant glioma before surgery to assess whether relaxometry can detect changes not visible on conventional images. Methods In a prospective study, 24 patients with suspected malignant glioma were examined before surgery. A standard MRI protocol was used with the addition of a quantitative MR method (MAGIC), which measured R-1, R-2, and proton density. The diagnosis of malignant glioma was confirmed after biopsy/surgery. In 19 patients synthetic MR images were then created from the MAGIC scan, and ROIs were placed in the peritumoral edema to obtain the quantitative values. Dynamic susceptibility contrast perfusion was used to obtain cerebral blood volume (rCBV) data of the peritumoral edema. Voxel-based statistical analysis was performed using a mixed linear model. Results R-1, R-2, and rCBV decrease with increasing distance from the contrast-enhancing part of the tumor. There is a significant increase in R1 gradient after contrast agent injection (Pamp;lt;.0001). There is a heterogeneous pattern of relaxation values in the peritumoral edema adjacent to the contrast-enhancing part of the tumor. Conclusion Quantitative analysis with relaxometry of peritumoral edema in malignant gliomas detects tissue changes not visualized on conventional MR images. The finding of decreasing R-1 and R-2 means shorter relaxation times closer to the tumor, which could reflect tumor invasion into the peritumoral edema. However, these findings need to be validated in the future.

    Place, publisher, year, edition, pages
    PUBLIC LIBRARY SCIENCE, 2017
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-138480 (URN)10.1371/journal.pone.0177135 (DOI)000402058800007 ()28542553 (PubMedID)
    Note

    Funding Agencies|Medical Research Council of Southeast Sweden [FORSS-234551]

    Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2017-11-16
  • Public defence: 2017-12-04 13:15 Ada Lovelace, B-huset, Linköping
    Wokiyi, Dennis
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Non-linear inverse geothermal problems2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The inverse geothermal problem consist of estimating the temperature distribution below the earth’s surface using temperature and heat-flux measurements on the earth’s surface. The problem is important since temperature governs a variety of the geological processes including formation of magmas, minerals, fosil fuels and also deformation of rocks. Mathematical this problem is formulated as a Cauchy problem for an non-linear elliptic equation and since the thermal properties of the rocks depend strongly on the temperature, the problem is non-linear. This problem is ill-posed in the sense that it does not satisfy atleast one of Hadamard’s definition of well-posedness.

    We formulated the problem as an ill-posed non-linear operator equation which is defined in terms of solving a well-posed boundary problem. We demonstrate existence of a unique solution to this well-posed problem and give stability estimates in appropriate function spaces. We show that the operator equation is well-defined in appropriate function spaces.

    Since the problem is ill-posed, regularization is needed to stabilize computations. We demostrate that Tikhonov regularization can be implemented efficiently for solving the operator equation. The algorithm is based on having a code for solving a well- posed problem related to the operator equation. In this study we demostrate that the algorithm works efficiently for 2D calculations but can also be modified to work for 3D calculations.

    List of papers
    1. An efficient regularization method for a large scale ill-posed geothermal problem
    Open this publication in new window or tab >>An efficient regularization method for a large scale ill-posed geothermal problem
    2017 (English)In: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 105, 1-9 p.Article in journal (Refereed) Published
    Abstract [en]

    The inverse geothermal problem consists of estimating the temperature distribution below the earth's surface using measurements on the surface. The problem is important since temperature governs a variety of geologic processes, including the generation of magmas and the deformation style of rocks. Since the thermal properties of rocks depend strongly on temperature the problem is non-linear.

    The problem is formulated as an ill-posed operator equation, where the righthand side is the heat-flux at the surface level. Since the problem is ill-posed regularization is needed. In this study we demonstrate that Tikhonov regularization can be implemented efficiently for solving the operator equation. The algorithm is based on having a code for solving a well-posed problem related to the above mentioned operator. The algorithm is designed in such a way that it can deal with both 2D and 3D calculations.

    Numerical results, for 2D domains, show that the algorithm works well and the inverse problem can be solved accurately with a realistic noise level in the surface data.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    National Category
    Earth and Related Environmental Sciences Mathematics
    Identifiers
    urn:nbn:se:liu:diva-139052 (URN)10.1016/j.cageo.2017.04.010 (DOI)000404697000001 ()
    Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2017-11-16Bibliographically approved
  • Persson, Eva (Editor, Photographer)
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Falk, Barbro (Editor)
    Wirén, Kristina (Photographer)
    Nionde nationella prioriterings-konferensen 2017: En summering2017Report (Other academic)
    Abstract [sv]

    Engagerat, angeläget och inspirerade. Så kan man sammanfatta den nionde nationella priorite­ringskonferensen som arrangerades i Kalmar den 23-25 oktober. Första dagen var det förmöte med grundkurs i prioriteringskunskap och de två följande dagarna bjöds det på ett fullspäckat program med intressanta sessioner. Omkring 300 personer från hela landet hade tagit sig till konferensanläggningen Kalmarsalen för att uppdatera sig på området, träffa kollegor och utbyta erfarenheter.

    Den nationella prioriteringskonferensen är en mötesplats för personer som arbetar med prioritering inom vård och omsorg på olika sätt och fokuserar på metoder och arbetssätt, organisering av prioriteringsprocesser, rollfördelning mellan aktörer, lämpliga beslutsunderlag etc. Temat för årets konferens var: ”Vårdens prioriteringar – union eller konflikt?”.

    Konferensen äger rum vartannat år och nu var det den nionde gången som arrangemanget gick av stapeln. För värdskapet i år svarade Landstinget i Kalmar län i samarbete med Prioriterings-centrum vid Linköpings universitet. Moderator under konferensen var Christina Kennedy, chefredaktör på Dagens Medicin.

  • Andersson, Timmy
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Eriksson Thorell, Jimmy
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Den självupplevda anställningsbarheten inom en gränslös karriär: En kvalitativ studie2017Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: Theories regarding the boundaryless career emerged to explain career paths that are not linear or confined to a single organisation throughout an individual’s career. The big difference within this new theory is that the individual takes responsibility for their career development instead of the organisation. The central term within these theories is employability, which describes the potential ability an individual has to change their career path.

    Purpose: The purpose of the study was to investigate how the individuals within a boundaryless career perceive their employability. Since most of the research within this area is conducted from an organisational point of view, there is a lack of research from an individual’s perspective and our aim is to increase understanding in this area.

    Method: We used a qualitative research approach in the study to capture the respondent’s subjective opinions about employability through the use of interviews. In total four interviews were conducted with individuals who fall within the definition of a boundaryless career, by use of a convenience sample.

    Conclusion: The respondent’s view two dimensions that affect employability and these are career identity and human capital. The ability to secure employment can be divided into two processes; opportunity creation and opportunity realisation. Respondent’s regard human capital and career identity as important for both opportunity and realisation processes, but view social capital as only affecting opportunity creation with no effect on realisation. We have concluded that the term employability has shortcomings compared to its theoretical basis. The term should include the process of opportunity creation as well as the ability to keep your current employment status.

  • Bikic, Sabina
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Sheibani, Alexander
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Att bedöma eller inte bedöma problem med fortsatt drift, det är frågan: En kvantitativ studie om revisorns bedömning av fortsatt drift2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Introduction: Going  concern  assessment  is  a  subject  that  causes  many auditors anxiety. At the same time it is a fundamental prerequisite for performing audit of high quality. Previous studies in the field have studied the phenomenon based on secondary data. This study aims at using primary data based on alternative research methods to supplement earlier studies through a Swedish context.

    Purpose: The purpose of this study is to explain the differences in the auditor’s going concern assessment.

    Method: The study is based on a quantitative research method with a deductive approach. A cross-sectional design has been used and research data has been collected through auditor’s participation through a survey. This study has been supplemented with qualitative data collected through follow- up interviews

    Conclusion: The result of the study indicate that auditors are a homogeneous group and that there are a number of underlying factors that are crucial in assessing going concern, such as ongoing dialogue with client and access to the clients future oriented profitability information.

  • Sanderson, Ann-Louise
    Linköping University, Department of Behavioural Sciences and Learning, Disability Research.
    Omsorgspersonals upplevelse av sitt bemötande av personer med självskadebeteende2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In research, self-injuring is described as complex, hard to understand and treat. Several studies are pointing to the lack of knowledge within the area, and also to information and guidance on how to deal with these behaviors. There are a handful of studies, which sheds light on individuals who have felt that care providers have treated them with negative attitudes. The purpose of the present study is to get a deeper understanding of how care providers approach individuals who self-injure. The main focus lies on how care providers experience how they themselves act when self-injuring occurs. It is also explored how care providers are affected while working with people who self-injuries.

    The study is qualitative with a phenomenological method. Four female care providers have been interviewed. In the analysis that had a phenomenological outset, six themes came forth: approach, shows the care provider´s different approaches to individuals who self-injures. The approach varies depending on the situations that arises, and also the severity of the self-injuring. Strategy, which illuminates how care providers works with different strategies in different stages of self-injuring, which can consist of activities, care and through conversation depending on the individual´s current situation. Hardships - the complex situation, which made clear that care providers experience hardships while treating people who self-injures. Creating trust, sheds light on the importance of a good communication. Self-injuring has an emotional impact, describes the care provider´s feelings of fear, insecurity, worry and frustration which arises while treating individuals who self-harm. Lastly the theme of the need for increased knowledge discusses if the care provider´s experiences their own way of treating people whom self-harm as appropriate behavior.

  • Public defence: 2017-12-07 09:00 Berzeliussalen, Linköping
    Kihlberg, Johan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Magnetic Resonance Imaging of Myocardial Deformation and Scarring in Coronary Artery Disease.2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Although improved treatments have reduced the rates of acute complications from myocardial infarction, sequelae such as heart failure and sudden death threaten the future wellbeing of those patients. Secondary prevention after myocardial infarction is related to cardiovascular risk factors and the effect of the infarct on left ventricular function. Cardiovascular magnetic resonance imaging (CMR) is necessary to determine the size of the infarct scar and can with great precision determine left ventricular volumes, left ventricular ejection fraction, and deformation (strain and torsion). The purpose of this thesis was to improve on CMR methods to facilitate image acquisition and post processing in patients with high risk of coronary artery disease (CAD).

    In Paper 1, a three-dimensional phase-sensitive inversion-recovery (3D PSIR) sequence was modified to measure T1 during a single breath hold. The measured T1 values were used to extrapolate a map of T1 relaxation, which avoided the time-consuming manual determination of the inversion time. The data collection consisted of phantom experiments, Monte Carlo simulations of the effect of various heart rates, and clinical investigation of 18 patients with myocardial infarction. Scar images created with the modified sequence were compared to those created with the standard sequence. The 3D PSIR sequence was able to measure T1 relaxation with a high accuracy up to 800 ms, which is in the suitable range for scar imaging. Simulated arrhythmias showed that the method was robust and able to tolerate some variation in heart rate. The modified sequence provides measurements of inversion time that can be used to facilitate standard scar imaging or to reconstruct synthetic scar images. Images of infarct scar obtained with the 3D PSIR sequence bore striking similarity to images obtained with the standard sequence.

    In Paper 2, 125 patients with high risk of CAD were investigated using the displacement encoding with stimulated echoes (DENSE) sequence. Image segments with infarct scar area >50% (transmurality) could be identified with a sensitivity of 95% and a specificity of 80% based on circumferential strain calculated from the DENSE measurements. The DENSE sequence was also applied in other directions, but its sensitivity and specificity to detect scar was lower than when used for circumferential strain.

    In Paper 3, 90 patients with high risk of CAD were examined by DENSE, tagging with harmonic phase (HARP) imaging and cine imaging with feature tracking (FT), to detect cardiac abnormalities as manifested in end-systolic circumferential strain. Circumferential strain calculated with DENSE had higher sensitivity and specificity than the competing methods to detect infarction with transmurality >50%. Global circumferential strain measured by DENSE correlated better with global parameters such as left ventricular ejection fraction, myocardial wall mass, left ventricular end-diastolic and end-systolic volume; than strain measured by FT or HARP.

    In Paper 4, myocardial torsion was investigated using DENSE, HARP, and FT in 48 patients with high risk of CAD. Torsion measured by each of the three methods was correlated with other global measures such as left ventricular ejection fraction, left ventricular mass, and left ventricular end-diastolic and end-systolic volumes. The torsion measurements obtained with DENSE had a stronger relationship with left ventricular ejection fraction, left ventricular mass, and volumes than those obtained with HARP or FT.

    DENSE was superior to the other methods for strain and torsion measurement and can be used to describe myocardial deformation quantitatively and objectively.

    List of papers
    1. Rapid T1 quantification based on 3D phase sensitive inversion recovery
    Open this publication in new window or tab >>Rapid T1 quantification based on 3D phase sensitive inversion recovery
    2010 (English)In: BMC Medical Imaging, ISSN 1471-2342, Vol. 10, no 19Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: In Contrast Enhanced Magnetic Resonance Imaging fibrotic myocardium can be distinguished from healthy tissue using the difference in the longitudinal T1 relaxation after administration of Gadolinium, the so-called Late Gd Enhancement. The purpose of this work was to measure the myocardial absolute T1 post-Gd from a single breath-hold 3D Phase Sensitivity Inversion Recovery sequence (PSIR). Equations were derived to take the acquisition and saturation effects on the magnetization into account.

    METHODS: The accuracy of the method was investigated on phantoms and using simulations. The method was applied to a group of patients with suspected myocardial infarction where the absolute difference in relaxation of healthy and fibrotic myocardium was measured at about 15 minutes post-contrast. The evolution of the absolute R1 relaxation rate (1/T1) over time after contrast injection was followed for one patient and compared to T1 mapping using Look-Locker. Based on the T1 maps synthetic LGE images were reconstructed and compared to the conventional LGE images.

    RESULTS: The fitting algorithm is robust against variation in acquisition flip angle, the inversion delay time and cardiac arrhythmia. The observed relaxation rate of the myocardium is 1.2 s-1, increasing to 6 - 7 s-1 after contrast injection and decreasing to 2 - 2.5 s-1 for healthy myocardium and to 3.5 - 4 s-1 for fibrotic myocardium. Synthesized images based on the T1 maps correspond very well to actual LGE images.

    CONCLUSIONS: The method provides a robust quantification of post-Gd T1 relaxation for a complete cardiac volume within a single breath-hold.

    National Category
    Engineering and Technology Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-59065 (URN)10.1186/1471-2342-10-19 (DOI)20716333 (PubMedID)
    Available from: 2010-09-08 Created: 2010-09-08 Last updated: 2017-11-15
    2. Clinical experience of strain imaging using DENSE for detecting infarcted cardiac segments
    Open this publication in new window or tab >>Clinical experience of strain imaging using DENSE for detecting infarcted cardiac segments
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    2015 (English)In: Journal of Cardiovascular Magnetic Resonance, ISSN 1097-6647, E-ISSN 1532-429X, Vol. 17, 50Article in journal (Refereed) Published
    Abstract [en]

    Background

    We hypothesised that myocardial deformation determined with magnetic resonance imaging (MRI) will detect myocardial scar.

    Methods

    Displacement Encoding with Stimulated Echoes (DENSE) was used to calculate left ventricular strain in 125 patients (29 women and 96 men) with suspected coronary artery disease. The patients also underwent cine imaging and late gadolinium enhancement. 57 patients had a scar area >1 % in at least one segment, 23 were considered free from coronary artery disease (control group) and 45 had pathological findings but no scar (mixed group). Peak strain was calculated in eight combinations: radial and circumferential strain in transmural, subendocardial and epicardial layers derived from short axis acquisition, and transmural longitudinal and radial strain derived from long axis acquisitions. In addition, the difference between strain in affected segments and reference segments, “differential strain”, from the control group was analysed.

    Results

    In receiver-operator-characteristic analysis for the detection of 50 % transmurality, circumferential strain performed best with area-under-curve (AUC) of 0.94. Using a cut-off value of -17 %, sensitivity was 95 % at a specificity of 80 %. AUC did not further improve with differential strain. There were significant differences between the control group and global strain circumferential direction (-17 % versus -12 %) and in the longitudinal direction (-13 % versus -10 %). Interobserver and scan-rescan reproducibility was high with an intraclass correlation coefficient (ICC) >0.93.

    Conclusions

    DENSE-derived circumferential strain may be used for the detection of myocardial segments with >50 % scar area. The repeatability of strain is satisfactory. DENSE-derived global strain agrees with other global measures of left ventricular ejection fraction.

    Place, publisher, year, edition, pages
    BioMed Central, 2015
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-119846 (URN)10.1186/s12968-015-0155-8 (DOI)000356652000001 ()26104510 (PubMedID)
    Available from: 2015-06-26 Created: 2015-06-26 Last updated: 2017-11-15
  • Public defence: 2017-12-08 10:15 Schrödinger, Fysikhuset, Linköping
    Wang, Chuanfei
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Electronic Structure of π-Conjugated Materials and Their Effect on Organic Photovoltaics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The great tunability of structure and electronic properties of π-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided.

    Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here.

    Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination.

    Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.

    List of papers
    1. Low Band Gap Polymer Solar Cells With Minimal Voltage Losses
    Open this publication in new window or tab >>Low Band Gap Polymer Solar Cells With Minimal Voltage Losses
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    2016 (English)In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 6, no 18, 1600148Article in journal (Refereed) Published
    Abstract [en]

    One of the factors limiting the performance of organic solar cells (OSCs) is their large energy losses (E-loss) in the conversion from photons to electrons, typically believed to be around 0.6 eV and often higher than those of inorganic solar cells. In this work, a novel low band gap polymer PIDTT-TID with a optical gap of 1.49 eV is synthesized and used as the donor combined with PC 71 BM in solar cells. These solar cells attain a good power conversion efficiency of 6.7% with a high open-circuit voltage of 1.0 V, leading to the E-loss as low as 0.49 eV. A systematic study indicates that the driving force in this donor and acceptor system is sufficient for charge generation with the low E-loss. This work pushes the minimal E-loss of OSCs down to 0.49 eV, approaching the values of some inorganic and hybrid solar cells. It indicates the potential for further enhancement of the performance of OSCs by improving their V-oc since the E-loss can be minimized.

    Place, publisher, year, edition, pages
    WILEY-V C H VERLAG GMBH, 2016
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-133010 (URN)10.1002/aenm.201600148 (DOI)000387132200002 ()
    Note

    Funding Agencies|Swedish Research Council; Swedish Research Council Formas; Swedish Energy Agency; Chalmers Area of Advance Energy and Materials Science; EU projects SUNFLOWER-"SUstainable Novel FLexible Organic Watts Efficiently Reliable" [287594]; Knut and Alice Wallenberg foundation; program for the Excellent Doctoral Dissertations of Guangdong Province [ybzzxm201114]; China Scholarship Council; National Natural Science Foundation of China [21504066, 21534003]; Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy [DE-AC02-05CH11231]

    Available from: 2016-12-08 Created: 2016-12-07 Last updated: 2017-11-15
    2. Ternary organic solar cells with enhanced open circuit voltage
    Open this publication in new window or tab >>Ternary organic solar cells with enhanced open circuit voltage
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    2017 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 37, 24-31 p.Article in journal (Refereed) Published
    Abstract [en]

    By introducing a non-fullerene small molecule acceptor as a third component to typical polymer donor: fullerene acceptor binary solar cells, we demonstrate that the short circuit current density (J(sc)), open circuit voltage (V-oc), power conversion efficiency (PCE) and thermal stability can be enhanced simultaneously. The different surface energy of each component causes most of the non-fullerene acceptor molecules to self-organize at the polymer/fullerene interface, while the appropriately selected oxidation/reduction potential of the non-fullerene acceptor enables the resulting ternary junction to work through a cascade mechanism. The cascade ternary junction enhances charge generation through complementary absorption between the non-fullerene and fullerene acceptors and aids the efficient charge extraction from fullerene domains. The bimolecular recombination in the ternary blend layer is reduced as the ternary cascade junction increases the separation of holes and electrons during charge transportation and the trap assistant recombination induced by integer charge transfer (ICT) state potentially reduced due to the smaller pinning energy of inserted non-fullerene acceptor, leading to an unprecedented increase in the open circuit voltage beyond the binary reference values.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE BV, 2017
    Keyword
    Ternary organic solar cell; Self-organization; Higher open circuit voltage; Generality; More thermal stable
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-138887 (URN)10.1016/j.nanoen.2017.04.060 (DOI)000402704500004 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation; Swedish Research Council [2013-4022]; Ministry of Science and Technology [2016YFA0200700]; NSFC [21504066, 21534003]; Goran Gustafsson Foundation for Research in Natural Sciences and Medicine; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkping University [2009 00971]; China Scholarship Council; Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]

    Available from: 2017-06-27 Created: 2017-06-27 Last updated: 2017-11-15
    3. Ternary Organic Solar Cells with Minimum Voltage Losses
    Open this publication in new window or tab >>Ternary Organic Solar Cells with Minimum Voltage Losses
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    2017 (English)In: Advanced Energy Materials, ISSN 1614-6840, Vol. 7, no 21, 1700390Article in journal (Refereed) Published
    Abstract [en]

    A new strategy for designing ternary solar cells is reported in this paper. A low-bandgap polymer named PTB7-Th and a high-bandgap polymer named PBDTTS-FTAZ sharing the same bulk ionization potential and interface positive integer charge transfer energy while featuring complementary absorption spectra are selected. They are used to fabricate efficient ternary solar cells, where the hole can be transported freely between the two donor polymers and collected by the electrode as in one broadband low bandgap polymer. Furthermore, the fullerene acceptor is chosen so that the energy of the positive integer charge transfer state of the two donor polymers is equal to the energy of negative integer charge transfer state of the fullerene, enabling enhanced dissociation of all polymer donor and fullerene acceptor excitons and suppressed bimolecular and trap assistant recombination. The two donor polymers feature good miscibility and energy transfer from high-bandgap polymer of PBDTTS-FTAZ to low-bandgap polymer of PTB7-Th, which contribute to enhanced performance of the ternary solar cell.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2017
    Keyword
    binary equivalent, minimum voltage losses, same bulk and interface energy, ternary solar cells
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:liu:diva-143026 (URN)10.1002/aenm.201700390 (DOI)
    Available from: 2017-11-15 Created: 2017-11-15 Last updated: 2017-11-15Bibliographically approved
    4. Pyrrolo[3,4-g]quinoxaline-6,8-dione-based conjugated copolymers for bulk heterojunction solar cells with high photovoltages
    Open this publication in new window or tab >>Pyrrolo[3,4-g]quinoxaline-6,8-dione-based conjugated copolymers for bulk heterojunction solar cells with high photovoltages
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    2015 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 6, no 25, 4624-4633 p.Article in journal (Refereed) Published
    Abstract [en]

    A new electron-deficient building block 5,9-di(thiophen-2-yl)-6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione (PQD) was synthesized via functionalizing the 6- and 7-positions of quinoxaline (Qx) with a dicarboxylic imide moiety. Side chain substitution on the PQD unit leads to good solubility which enables very high molecular weight copolymers to be attained. The fusion of two strong electron-withdrawing groups (Qx and dicarboxylic imide) makes the PQD unit a stronger electron-deficient moiety than if the unit had just one electron-withdrawing group, thus enhancing the intramolecular charge transfer between electron-rich and deficient units of the copolymer. Four PQD-based polymers were synthesized which feature deep-lying highest occupied molecular orbital (HOMO) levels and bathochromic absorption spectra when compared to PBDT-Qx and PBDT-TPD analogues. The copolymers incorporated with benzo[1,2-b:4,5-b]dithiophene (BDT) units show that the 1D and 2D structural variations of the side groups on the BDT unit are correlated with the device performance. As a result, the corresponding solar cells (ITO/PEDOT:PSS/polymer: PC71BM/LiF/Al) based on the four copolymers feature very high open-circuit voltages (V-oc) of around 1.0 V. The copolymer PBDT-PQD1 attains the best power conversion efficiency of 4.9%, owing to its relatively high absorption intensity and suitable film morphology. The structure-property correlation demonstrates that the new PQD unit is a promising electron-deficient building block for efficient photovoltaic materials with high V-oc.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2015
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-120071 (URN)10.1039/c5py00394f (DOI)000356298900009 ()
    Note

    Funding Agencies|Swedish Research Council; Swedish Energy Agency; EU [287594]; China Scholarship Council; program for the Excellent Doctoral Dissertations of Guangdong Province [ybzzxm201114]

    Available from: 2015-07-06 Created: 2015-07-06 Last updated: 2017-11-15
  • Wemmert, Oscar
    Linköping University, Department of Computer and Information Science.
    Toward an on-line preprocessor for Swedish2017Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis presents OPT (Open Parse Tool), a java program allowing for independent parsers/taggers to be run in sequence. For this thesis the existing java versions of Stagger and Maltparser has been adapted for use as modules in this program, and OPT's performance has then been compared to an existing, in use, alternative (Språkbanken's Korp Corpus Pipeline, henceforth KCP). Execution speed has been compared, and OPT's accuracy has been coarsly tested as either comparable or divergent to that of KCP. The same collection of documents containing natural text has been fed through OPT and KCP in sequence, and execution time was recorded. The tagged output of OPT and KCP was then run through SCREAM (Sjöholm, 2012) and if SCREAM produced comparable results between the two, the accuracy of OPT was considered as comparable to KCP. The results show that OPT completes its tagging and parsing of the documents in around 35 minutes, while KCP took over four hours to complete. SCREAM performed almost exactly the same using the outputs of either program, except for one case in which OPT's output gave better results than KCP's. The accuracy of OPT was thus considered comparable to KCP. The one divergent example can not fully be understood or explained in this thesis, given that the thesis considers SCREAM's internals as mostly that of a black box.

  • Public defence: 2017-12-01 13:00 Runstenen, Norrköping
    Bäckström, Denise
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Anaesthesiology and Intensive Care in Norrköping.
    Injury mortality in Sweden; changes over time and the effect of age and injury mechanism2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Injuries are one of the most common causes of death in the world. Varying types of injuries dominate in different parts of the world, which also have separate influences mortality. In Scandinavia blunt injuries dominates and the majority of those who die do so pre hospital. Over time different injury pattern may vary and by analyzing this we can assess when, where and how preventive work can be reinforced. The aim of this thesis was to study injury epidemiology in Sweden and assess the contribution of different injury patters on mortality.

    Method: We used the Swedish cause of death and the national patient registries which have a complete national coverage. ICISS was calculated (based on ICD-10) in the in hospital population. We have chosen to do this investigation with a broad perspective using the term injury, which includes trauma but also other diagnoses like suffocation and drowning.

    Results: During the study period (1999-2012) the number of deaths because of injury was 1213, 25 388, and 18 332 among children, working age and elderly, respectively. Mortality declined in the children and in the working age but inclined in the elderly. Mortality increased with each age group except between the ages of 15–25 and 26–35 years. One thousand two hundred sixty four (97%) of those who died because of penetrating trauma (sharp objects and firearms) were killed by intentional trauma (assault and intentional self-harm). One thousand and seventeen (83%) of the children died prehospital. In the working age 22 211 (80%) of 25 388 died pre hospital. Nine thousand six hundred and eighteen (53%) of 18 332 of the elderly died prehospital. During 2001- 2011 the risk adjusted in hospital mortality decreased in traffic and assault but not in fall related injuries.

    Discussion: Largely, the anticipated injury mortality picture was found, with blunt injuries (traffic accidents) dominating in the working age and falls in elderly. Further a significant portion of the deaths occurred pre hospital. The intentional injuries are dominated by intentional selfharm. The decrease in child injury mortality is notable as Sweden already has one of the lowest incidences in child injury mortality in the world. The decrease in injury mortality in the working age also implies that preventive work has had an effect. The incline in injury mortality in elderly on the other hand needs to be further studied. Areas of particular importance for future preventive work is the incline in injury mortality in elderly and intentional injuries among children. 

    List of papers
    1. Change in child mortality patterns after injuries in Sweden: a nationwide 14-year study.
    Open this publication in new window or tab >>Change in child mortality patterns after injuries in Sweden: a nationwide 14-year study.
    2017 (English)In: European Journal of Trauma and Emergency Surgery, ISSN 1863-9933, E-ISSN 1863-9941, Vol. 43, no 3, 343-349 p.Article in journal (Refereed) Published
    Abstract [en]

    INTRODUCTION: Sweden has one of the world's lowest child injury mortality rates, but injuries are still the leading cause of death among children. Child injury mortality in the country has been declining, but this decline seems to decrease recently. Our objective was therefore to further examine changes in the mortality of children's death from injury over time and to assess the contribution of various effects on mortality. The underlying hypothesis for this investigation is that the incidence of lethal injuries in children, still is decreasing and that this may be sex specific.

    PATIENTS AND METHODS: We studied all deaths from injury in Sweden under-18-year-olds during the 14 years 1999-2012. We identified those aged under 18 whose underlying cause of death was recorded as International Classification of Diseases, 10th Revision (ICD-10) diagnosis from V01 to X39 in the Swedish cause of death, where all dead citizens are registered.

    RESULTS: From the 1 January 1999 to 31 December 2012, 1213 children under the age of 18 died of injuries in Sweden. The incidence declined during this period (r = -0.606, p = 0.02) to 3.3 deaths/100,000 children-years (95 % CI 2.6-4.2). Death from unintentional injury was more common than that after intentional injury (p < 0.0001). There was a reduction in the incidence of unintentional injuries during the study period (r = -0.757, p = 0.03). The most common causes of death were injury to the brain (n = 337, 41 %), followed by drowning (n = 109, 13 %). The number of deaths after intentional injury increased (r = 0.585, p = 0.03) and at the end of the period was 1.5 deaths/100,000 children-years. The most common causes of death after intentional injuries were asphyxia (n = 177, 45 %), followed by injury to the brain (n = 76, 19 %).

    DISCUSSION: Mortality patterns in injured children in Sweden have changed from being dominated by unintentional injuries to a more equal distribution between unintentional and intentional injuries as well as between sexes and the overall rate has declined further. These findings are important as they might contribute to the preventive work that is being done to further reduce mortality in injured children.

    Place, publisher, year, edition, pages
    Springer, 2017
    Keyword
    Children, Injury, Mortality, Scandinavia, Trauma
    National Category
    Other Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-135548 (URN)10.1007/s00068-016-0660-y (DOI)000402789500010 ()27084542 (PubMedID)
    Note

    Funding agencies: Swedish Carnegie Hero Fund

    Available from: 2017-03-16 Created: 2017-03-16 Last updated: 2017-11-02Bibliographically approved
    2. Deaths caused by injury among people of working age (18-64) are decreasing, while those among older people (64+) are increasing.
    Open this publication in new window or tab >>Deaths caused by injury among people of working age (18-64) are decreasing, while those among older people (64+) are increasing.
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    2017 (English)In: European Journal of Trauma and Emergency Surgery, ISSN 1863-9933, E-ISSN 1863-9941Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    BACKGROUND: Injury is an important cause of death in all age groups worldwide, and contributes to many losses of human and economic resources. Currently, we know a few data about mortality from injury, particularly among the working population. The aim of the present study was to examine death from injury over a period of 14 years (1999-2012) using the Swedish Cause of Death Registry (CDR) and the National Patient Registry, which have complete national coverage.

    METHOD: CDR was used to identify injury-related deaths among adults (18 years or over) during the years 1999-2012. ICD-10 diagnoses from V01 to X39 were included. The significance of changes over time was analyzed by linear regression.

    RESULTS: The incidence of prehospital death decreased significantly (coefficient -0.22, r (2) = 0.30; p = 0.041) during the study period, while that of deaths in hospital increased significantly (coefficient 0.20, r (2) = 0.75; p < 0.001). Mortality/100,000 person-years in the working age group (18-64 years) decreased significantly (coefficient -0.40, r (2) = 0.37; p = 0.020), mainly as a result of decrease in traffic-related deaths (coefficient -0.34, r (2) = 0.85; p < 0.001). The incidence of deaths from injury among elderly (65 years and older) patients increased because of the increase in falls (coefficient 1.71, r (2) = 0.84; p < 0.001) and poisoning (coefficient 0.13, r (2) = 0.69; p < 0.001).

    CONCLUSION: The epidemiology of injury in Sweden has changed during recent years in that mortality from injury has declined in the working age group and increased among those people 64 years old and over.

    Place, publisher, year, edition, pages
    Springer, 2017
    Keyword
    Elderly, Injury, Mortality, Prehospital, Trauma, Working age
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:liu:diva-142763 (URN)10.1007/s00068-017-0827-1 (DOI)28825159 (PubMedID)
    Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-02Bibliographically approved
  • Public defence: 2017-12-07 13:00 ACAS, A-huset, Linköping
    Nilsson, Sara
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    How requirements development could support design of effective and resource-efficient offerings2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    What a company offers its customers has to fulfil several different needs, desires, constraints, which can originate from multiple different sources that affect the offering throughout its life cycle. All these criteria have to come together and be translated into statements that can support the designer’s understanding of the offering’s purpose. This translation is done through a requirements development process to provide a controlled process to define statements that describe what the offering is supposed to fulfil.

    This research provides insights on key challenges and success factors in requirements development to support the design of effective and resource-efficient offerings. Namely, it identifies crucial sources and aspects to be considered, and a requirements development process demonstrating how to overcome identified challenges. By getting the requirements right from the beginning, sub-optimisation and unnecessary time and risks can be avoided. The consideration of accurate sources and aspects is considered to be one of the most important factors for the successful design of offerings. It is also in the earliest phases of design, that is to say requirements development, where one has the greatest possibility to affect the environmental impact of the offering. What is missing, however, is sufficient and appropriate support in industry on how to do so.

    The gap between the three areas of effectiveness and resource efficiency, design of integrated offerings, and requirements development has been investigated. Results are based on findings in the literature and in industry, identified primarily by qualitative studies. In the research, 15 different companies have been included through a number of interviews and discussions.

    Key sources and aspects to consider in the requirements development process are identified along with challenges, and success factors that can be utilised to overcome the identified challenges. This research’s final results include an adapted requirements development process that considers the earlier-mentioned sources and aspect, challenges, and success factors. Such a requirements development process should support the design of effective and resource-efficient offerings.

    List of papers
    1. A Literature Review to Understand the Requirements Specification’s Role when Developing Integrated Product Service Offerings
    Open this publication in new window or tab >>A Literature Review to Understand the Requirements Specification’s Role when Developing Integrated Product Service Offerings
    2016 (English)In: Product-Service Systems across Life Cycle / [ed] Sergio Cavalieri, Elisabetta Ceretti, Tullio Tolio, Giuditta Pezzotta, Elsevier, 2016, Vol. 47, 150-155 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper's objective is to analyze, based on a literature review, how existing IPSO design methods support and manage requirements when developing an IPSO. Issues analyzed are e.g. which types of aspects existing methods should consider, such as environmental issues and demands from stakeholders and customers. Another issue is what types of stakeholders are involved in the process. There is also an interest in finding out which of these methods are used in the industry. The goal is that the results will provide insight into how the requirements specification is used when developing an IPSO in theory, and in what way this insight will contribute to future studies on how companies currently derive and manage requirements when developing an IPSO.

    The literature review started out with the analysis of 201 papers, yielding 22 papers within the area of working with requirements for an IPSO. These papers were reviewed and summarized with the above issues and interests in mind. Findings are that when deriving requirements, existing IPSO design methods are lacking in regard to a holistic life cycle and system perspective of the offering. Few of the methods consider both requirements regarding the environmental impact of the offering and demands from all involved stakeholders, normally only the customer. Furthermore, few studies have ended with a clear work process regarding how to initially find the requirements to analyze them and later interpret them as actual metrics. There are also no signs that existing methodology is used in the industry's day-to-day work.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Series
    Procedia CIRP, ISSN 2212-8271 ; 47
    Keyword
    Product Service System (PSS), Integrated Product Service Engineering (IPSE), Engineering design
    National Category
    Other Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-130972 (URN)10.1016/j.procir.2016.03.225 (DOI)000387505100026 ()
    Conference
    8th CIRP IPSS CONFERENCE, Product-Service Systems across Life Cycle, Bergamo, Italy, June 20-21, 2016
    Projects
    Mistra REES
    Funder
    Mistra - The Swedish Foundation for Strategic Environmental Research
    Available from: 2016-09-01 Created: 2016-09-01 Last updated: 2017-11-15Bibliographically approved
    2. Integrating Requirements Engineering for Different Domains in System Development: Lessons Learnt from Industrial SME Cases
    Open this publication in new window or tab >>Integrating Requirements Engineering for Different Domains in System Development: Lessons Learnt from Industrial SME Cases
    2017 (English)In: Procedia CIRP: 9th CIRP IPSS Conference: Circular Perspectives on PSS / [ed] Tim C. McAloone, Daniela C.A. Pigosso, Niels Henrik Mortensen and Yoshiki Shimomura, Elsevier, 2017, Vol. 64, 351-356 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    There is a trending transition for companies from offering products to solutions in order to fulfill better customer needs and to reduce environmental impact by e.g. dematerialization. This solution-based development has an associated integration of intelligent devices that contributes to increasing system complexity. The ability of systems engineering processes, methods and tools to cope with these developments is a critical factor for manufacturing companies today. Still, in many cases it is hard to find adequately trained people and sufficiently integrated development tools for complex solutions, especially in the case of small and medium sized enterprises. Often, the tangible (hardware) part of the solution is primarily developed and the intangible parts (software and services) are added on top. However, key for a successful development is to adapt and integrate all parts according to the requirements set for the solution. Thus, it is essential how requirements are worked with during systems engineering and how they influence the development of the tangible and intangible parts of the solution. The objective of this paper is to study the approach of different industrial use cases for requirements engineering in system development. The aim is to identify how practices from domains like mechanical engineering, software or service engineering can be adapted for an integrated requirements engineering for complex systems, like product-service systems.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Series
    Procedia CIRP, ISSN 2212-8271
    Keyword
    Systems Engineering; Requirements Engineering; Product-Service Systems; Industrial Case Study
    National Category
    Other Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-138351 (URN)10.1016/j.procir.2017.03.013 (DOI)000414528200060 ()
    Conference
    9th CIRP IPSS Conference: Circular Perspectives on PSS, June 19-21, 2017, Copenhagen, Denmark
    Note

    Funding agencies:This work has been funded by the European Commission through the project PSYMBIOSYS: Product-Service sYMBIOtic SYStems (No. 636804) and by Mistra (The Swedish Foundation for Strategic Environmental Research) through the Mistra REES (Resource Efficient and Effective Solutions) program. The authors wish to acknowledge the funding bodies and all the project partners for their contribution.

    Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2017-11-20
  • Benson, Lydia
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science.
    Litström, Emma
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science.
    Att förebygga hypotermi hos bukkirurgiska patienter: En systematisk litteraturöversikt och metaanalys2017Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund: Hypotermi definieras som kärntemperatur under 36,0°C. Vid anestesi

    störs den fysiologiska regleringen av temperatur vilket är en av orsakerna till att

    risken för hypotermi under operation är stor. Peroperativt sker 90 % av

    värmeförlusterna från huden. Patientens riskfaktorer, anestesins längd och

    operationstid har betydelse i utveckling av hypotermi. Patienter som genomgår

    öppna bukoperationer som varar länge har hög risk för att utveckla hypotermi,

    bland annat på grund av stor exponerad kroppsyta.

    Syfte: Att utvärdera olika metoder för att förebygga peroperativ hypotermi hos

    sövda patienter som genomgår bukkirurgi.

    Metod: Systematisk litteraturstudie med metaanalys. Sökningar har gjorts i

    databaserna PubMed, CINAHL och SCOPUS.

    Resultat: Totalt 21 studier har inkluderats. Alla studier hade hypoterma patienter

    någon gång under det peroperativa förloppet, oavsett uppvärmningsmetod. Vid

    jämförelse av temperatur vid operationsslut uppvisades positivt resultat för både

    uppvärmd koldioxid och varmluftstäcke.

    Konklusion: Aktiv uppvärmning med varmluftstäcke tycks vara mest effektivt

    och är gold standard men trots aktiv uppvärmning blir många patienter hypoterma

    peroperativt. Det finns flera alternativ som visat sig vara lika effektiva som

    varmluftstäcke, så som värmelampor, eldriven värmemadrass och aktiv värmning

    med varmvatten. Troligen behövs en kombination av värmande metoder för att

    undvika hypotermi.

  • Soubiea, Nicholas
    Linköping University, Department of Management and Engineering, Malmstens Linköping University.
    Flexibelt boende: en multifunktionell möbel för begränsad bostadsyta2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The goal in my bachelor thesis has been to create a multifunctional furniture, a product in which the form has followed the function to allow the user variation for the body and practical functions. The purpose of this project has been to encourage reduction of unnecessary furniture within compact living spaces and instead offer better solutions to practical multifunctional furniture.

    In my research phase for this project I studied different forms of multifunctional furniture on the market as well as carried out different observational studies of student living and how students generally use their furniture. The first being various visits to different student rums and apartments. The other being a closer study at Malmstens school in which I allowed students to create their own space and interact with the furniture to study how the students used the furniture and how the students sat in the furniture. A basic, yet crucial, survey about multifunctional furniture was sent out to gather information on what people do at home and what type of furniture people prefer if they were to live in a compact space.

    The research gathered led to the next phase of the project in which many different sketching techniques, both 2d and 3d, resulted in a multifunctional furniture which offers variation within sitting and practical use. As a result of the analysis a furniture prototype will be built and shown at Malmstens Spring Exhibition and Vallastaden Living and House Society Exhibit in September 2017.

  • Cibis, Merih
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bustamante, Mariana
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Eriksson, Jonatan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Carlhäll, Carljohan
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Creating Hemodynamic Atlases of Cardiac 4D Flow MRI2017In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 46, no 5, 1389-1399 p.Article in journal (Refereed)
    Abstract [en]

    Purpose: Hemodynamic atlases can add to the pathophysiological understanding of cardiac diseases. This study proposes a method to create hemodynamic atlases using 4D Flow magnetic resonance imaging (MRI). The method is demonstrated for kinetic energy (KE) and helicity density (Hd). Materials and Methods: Thirteen healthy subjects underwent 4D Flow MRI at 3T. Phase-contrast magnetic resonance cardioangiographies (PC-MRCAs) and an average heart were created and segmented. The PC-MRCAs, KE, and Hd were nonrigidly registered to the average heart to create atlases. The method was compared with 1) rigid, 2) affine registration of the PC-MRCAs, and 3) affine registration of segmentations. The peak and mean KE and Hd before and after registration were calculated to evaluate interpolation error due to nonrigid registration. Results: The segmentations deformed using nonrigid registration overlapped (median: 92.3%) more than rigid (23.1%, P amp;lt; 0.001), and affine registration of PC-MRCAs (38.5%, P amp;lt; 0.001) and affine registration of segmentations (61.5%, P amp;lt; 0.001). The peak KE was 4.9 mJ using the proposed method and affine registration of segmentations (P50.91), 3.5 mJ using rigid registration (P amp;lt; 0.001), and 4.2 mJ using affine registration of the PC-MRCAs (P amp;lt; 0.001). The mean KE was 1.1 mJ using the proposed method, 0.8 mJ using rigid registration (P amp;lt; 0.001), 0.9 mJ using affine registration of the PC-MRCAs (P amp;lt; 0.001), and 1.0 mJ using affine registration of segmentations (P50.028). The interpolation error was 5.262.6% at mid-systole, 2.863.8% at early diastole for peak KE; 9.669.3% at mid-systole, 4.064.6% at early diastole, and 4.964.6% at late diastole for peak Hd. The mean KE and Hd were not affected by interpolation. Conclusion: Hemodynamic atlases can be obtained with minimal user interaction using nonrigid registration of 4D Flow MRI. Level of Evidence: 2 Technical Efficacy: Stage 1

  • Krantz, Dino
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Methodology and vibrational analysis for measurements on a VTOL RAPS2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a methodology for measuring vibrations has been produced andinvestigated for APID 60, a rotorcraft in a Vertical Take-off and landing remotelypiloted aircraft system (VTOL RPAS). A comparative study was carried out forthe purpose of identifying the methodology with respect to design modificationscommon to the APID 60. The pilot-study identified experimental modal analysis(EMA) as a feasible part of the methodology for experimentally extracting themodal parameters of a structure. The EMA was performed on the main frameof the APID 60 where an impact hammer test was chosen as the technique forextracting the response data. As a comparison a point mass was added to thestructure to alter the dynamic properties and the test was repeated.The results from the EMA was compared with a modal analysis performednumerically with a calculation software. Comparison of the results from EMAwith the modal analysis performed numerically indicates consistency. This confirmsa good reliability of the methodology produced. However, the structure onwhich the test were preformed is simple in terms of constant structural properties.Further work should therefore investigate whether this methodology of measuringvibrations could be successfully applied to a structure with higher complexity.

  • Henriksson, Fredrik
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    Johansen, Kerstin
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    Including Student Case Projects in Integrated Product and Production Development Research – Methodology Description and Discussion2016Conference paper (Other academic)
    Abstract [en]

    Within integrated product and production development research, casestudies needto be performed for data gathering purposes. Today, there are two commonly used ways to perform this research; observingindustry projects orhaving the researchers perform the projects themselves. The first option can pose data access and IPRissues, and the second optioncomes with biasing risks. Another approach is to work with studentcaseprojects, givingstudents interesting projects and findinga solution to mediate both data gathering opportunity and biasing risks. This approach has been tested at Linköping University, with students performing projects in the Vinnovafunded Production 2030 –Large Scale Production in Mixed Materials project. Two larger student case projects have been performed on the topic of material substitution and mixed material solutions within the automotive industry.In this paper, the method used to include student projects is presented along with identified benefits and drawbacks. Including student case projects in research have shown to be beneficial in research on processes, projects and methodology, but needs to be complemented by data fromindustry projects and the researcher ́s own work within integrated product and production development in order to create a more reliable analysis with high level of detail.

  • Hjelm, Wilhelm
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Grändevall, Patrik
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Sätt fler användare i centrum med åldersresponsiv design2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Under 2017 spås det att de första åldersresponsiva webbplatserna kommer publiceras. En webbplats som inte bara anpassar sig efter vilken enhet besökaren kommer från, utan även användarens ålder. I denna studie finner vi vilka problem som kan knytas till just användarens ålder.

  • Stenberg, Johan
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Snail Quest: A usability comparison of motion control and keyboardcontrol in a puzzle game2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Movement based controls in games hold great promise for public health, player enjoyment and intuitive controls. A system employing the web camera for motion control of games or other software might be a way to bring motion control to the consumers en masse. But does motion based controls offer an advantage in usability compared to the conventional keyboard? This study attempts to compare the usability of game controlled by such a system with the usability of the same game being controlled with the keyboard. To that end Snail Quest was developed. Snail Quest is a small 2D platformer puzzle game developed for the motion controller. A user study was performed to measure the usability of the game while used with each controller, the motion controller and the keyboard. Assuming the validity of the questionaire used, the results are largely inconclusive. The motion controller scored on par with the keyboard for the first of the two levels evaluated by the studies participants, but in the second level the keyboard received a uneqivocally higher score. Even so, statement nr 2 of the questionaire: “It was easy to use the game” consistently recieved higher scores when the game was played using the keyboard regardless of level, suggesting the game and/or the MBC may need improvement to compete with traditional controls in usability.

  • Larsson, Erik
    et al.
    Linköping University, Department of Management and Engineering, Information Systems. Linköping University, Faculty of Arts and Sciences.
    Lind, Joakim
    Linköping University, Department of Management and Engineering, Information Systems. Linköping University, Faculty of Arts and Sciences.
    Generisk dataportabilitet för personuppgifter: En kvalitativ fallstudie av Region Östergötland2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the context of the new General Data Protection Regulation (GDPR) within EU, new legislation is added upon how organizations are permitted to process EU citizens’ personal data. One of the changes is the right to data portability which sets the requirements that organizations must be able to transfer subjects’ personal data to the subject itself or to other data controllers. This implicates comprehensive challenges for organizations’ capacity to reach interoperability in relation to other actors’ based on juridical, organizational, technical and semantic interoperability. In light of the requirement of data portability, interoperability comes into focus as a condition for organizations to comply with the GDPR regulation.

    In consideration of this background, a public organization that is affected by the data protection reform and the data portability requirement is being studied. In the study, a deepening is made on how the organization manage their systems and structures as well as working with standards and co-operations to reach interoperability in accordance with data portability. The studied case contributes with insights on how organizations can work with similar issues that consider data portability and interoperability.

    In the study it is clear that the case organization is already working with interoperability issues. This as a result of the organizations own attention of related issues and not only as an effect due to the new data protection regulation and its requirement of data portability. In effect of the data protection regulation, an ongoing analysis is made within the case organization to investigate which actions are needed, where the right to data portability is one of the areas to deal with. The organization identify challenges mainly within the interpretation of the GDPR, organizational and semantic interoperability. The work on how to comply with the requirements is in progress, and the organization follow the recommendations which are given by advising organizations both within EU and on national level. The contribution of the study is deepening knowledge on the relevance of interoperability as a condition to achieve data portability contextualized by the GDPR. Our study shows the relevance of how common rules between different actors in the form of common legislation contributes to improved prerequisites to reach interoperability on all four levels, namely, organizational, juridical, technical and semantic interoperability, which from what our study show is crucial for data portability. The study also contributes with a useful conceptual model to evaluate interoperability as a prerequisite to achieve data portability for organizations.

  • Public defence: 2017-12-15 09:00 Berzeliussalen, Linköping
    Pompermaier, Laura
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Outcome of burn care: the mortality perspective2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Despite the improvements in burn care during the last decades, burns remain catastrophic for the patients and a challenge for the care-givers.  The early outcome of burn care is to assess its quality and to improve it, but the crucial outcome is mortality, which is the main focus of this thesis. In particular, I address questions about mortality that have arisen from working with burned patients and that can have clinical consequences: the impact of pre- existing medical conditions; long-term survival; the causes of unexpected deaths; and the possible differences between sexes in the provision of resources.

    Patients with burns share the fact that the time of their injury is known, its severity can be quantified from the size of the burn, and the care is relatively standardised. The analysis of outcome among burned patients treated at a single burn centre may therefore be of general value to others who treat burns.

    Methods: We retrospectively analysed data that had been collected prospectively (the burn    unit database) from patients with burns admitted consecutively to a national burn centre in Sweden during the last 25 years.

    Results: Age and percentage of total body surface area burned (TBSA %) affected the in- hospital mortality, whereas pre-existing medical conditions did not influence the prediction of outcome (Paper I). After discharge, both age and the presence of full thickness burns reduced the long-term survival, whereas the extent of the burn (TBSA %) did not (Paper II). Most patients with moderate burns who die in hospital despite a good prognosis, die for reasons   other than the burn (Paper III). Previously, it has been shown that sex is not an independent factor for mortality during burn care; in this thesis we show that the sex of the patients did not affect the number of medical interventions given either (Paper IV).

    Conclusion: The addition of “coexisting condition” to a mortality model based on age and   size of burn does not improve its predictive value; rather, the factor “age” is sufficient to adjust for comorbidity in the assessment of a burn and its outcome (Paper I).

    If patients with burns survive, the long-term prognosis is good. The effect of age is the one that governs survival, whereas the effect of the extent of the burn ends when the patient is discharged (Paper II).

    The in-hospital mortality during burn care is low, but some patients die for reasons other than the actual burn (Paper III).

    In a centre where the mortality is independent of the sex of the patient, the provision of medical interventions is also equal between men and women (Paper IV).

    List of papers
    1. Inclusion of coexisting morbidity in a TBSA% and age based model for the prediction of mortality after burns does not increase its predictive power
    Open this publication in new window or tab >>Inclusion of coexisting morbidity in a TBSA% and age based model for the prediction of mortality after burns does not increase its predictive power
    2015 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 41, no 8, 1868-1876 p.Article in journal (Refereed) Published
    Abstract [en]

    Introduction: Several models for predicting mortality have been developed for patients with burns, and the most commonly used are based on age and total body surface area (TBSA%). They often show good predictive precision as depicted by high values for area under the receiver operating characteristic curves (AUC). However the effect of coexisting morbidity on such prediction models has not to our knowledge been thoroughly examined. We hypothesised that adding it to a previously published model (based on age, TBSA%, full thickness burns, gender, and need for mechanical ventilation) would further improve its predictive power. Methods: We studied 772 patients admitted during the period 1997-2008 to the Linkoping University Hospital, National Burn Centre with any type of burns. We defined coexisting morbidity as any of the medical conditions listed in the Charlson list, as well as psychiatric disorders or drug or alcohol misuse. We added coexisting medical conditions to the model for predicting mortality (age, TBSA%, and need for mechanical ventilation) to determine whether it improved the model as assessed by changes in deviances between the models. Results: Mean (SD) age and TBSA% was 35 (26) years and 13 (17) %, respectively. Among 725 patients who survived, 105 (14%) had one or more coexisting condition, compared with 28 (60%) among those 47 who died. The presence of coexisting conditions increased with age (p &lt; 0.001) among patients with burns. The AUC of the mortality prediction model in this study, based on the variables age, TBSA%, and need for mechanical ventilation was 0.980 (n = 772); after inclusion of coexisting morbidity in the model, the AUC improved only marginally, to 0.986. The model was not significantly better either. Conclusion: Adding coexisting morbidity to a model for prediction of mortality after a burn based on age, TBSA%, and the need for mechanical ventilation did not significantly improve its predictive value. This is probably because coexisting morbidity is automatically adjusted for by age in the original model. (C) 2015 Elsevier Ltd and ISBI. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCI LTD, 2015
    Keyword
    Burns; Comorbidity; Mortality; Prediction model
    National Category
    Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-124131 (URN)10.1016/j.burns.2015.09.017 (DOI)000367127700031 ()26507519 (PubMedID)
    Available from: 2016-01-22 Created: 2016-01-19 Last updated: 2017-11-09
    2. Long-term survival after burns in a Swedish population
    Open this publication in new window or tab >>Long-term survival after burns in a Swedish population
    Show others...
    2017 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 43, no 1, 157-161 p.Article in journal (Refereed) Published
    Abstract [en]

    INTRODUCTION: As widely reported, the progress in burn care during recent decades has reduced the hospital mortality. The effect of the burns on long-term outcome has not received so much attention, and more study is indicated. The aim of this retrospective study was to investigate the long-time survival among patients who had been treated for burns.

    METHODS: We studied 1487 patients who were discharged alive from the Linköping University Hospital Burn Centre during the period 1993 until the end of December 2012. We used Cox's regression analysis to study the effect of burns on long-term survival after adjustment for different factors.

    RESULTS: Age and a full-thickness burn were significantly associated with mortality after discharge (p<0.001), whereas percentage of total body surface area burned (TBSA %), need for mechanical ventilation, and gender were not. Less than 1% of the patients with burns (13/1487) died within 30 days of discharge and a total of 176/1487 (12%) died during follow-up.

    CONCLUSION: Age and full-thickness burns reduce the long-time survival after discharge from the Burn Centre, whereas the effect of TBSA% and need for artificial ventilation ends with discharge.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keyword
    Burns, Outcome, Long-term survival, Mortality
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:liu:diva-131478 (URN)10.1016/j.burns.2016.07.018 (DOI)000392476000022 ()27613474 (PubMedID)
    Note

    Funding agencies: Department of Hand and Plastic Surgery Linkoping University Hospital; Region of Ostergotland; Linkoping University, Linkoping, Sweden

    Available from: 2016-09-22 Created: 2016-09-22 Last updated: 2017-11-09Bibliographically approved
    3. Burned patients who die from causes other than the burn affect the model used to predict mortality: a national exploratory study.
    Open this publication in new window or tab >>Burned patients who die from causes other than the burn affect the model used to predict mortality: a national exploratory study.
    Show others...
    2017 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    INTRODUCTION: The Baux score - the sum of age and total body surface area burned (TBSA %) - is a good predictor of mortality has a high specificity but low sensitivity. Our aim was to examine the causes of death in patients who die with Baux scores of <100, which may explain the lower sensitivity and possibly affect the prediction of mortality.

    METHODS: All patients admitted to our centre for burn care from 1993 to 2015 (n=1946) were included in this retrospective, descriptive, exploratory study. The study group comprised those patients who died with Baux scores of <100 (n=23), and their medical charts were examined for the cause of death and for coexisting diseases.

    RESULTS: Crude mortality was 5% (93/1946) for the overall cohort, and a quarter of the patients who died (23/93) had Baux scores of less than 100 (range 64-99). In this latter group, flame burns were the most common (18/23), the median (10th-90th centile) age was 70 (46-86) years and for TBSA 21 (5.0-40.5) %, of which 7 (0-27.0) % of the area was full thickness. The main causes of death in 17 of the 23 were classified as "other than burn", being cerebral disease (n=9), cardiovascular disease (n=6), and respiratory failure (n=2). Among the remaining six (burn-related) deaths, multiple organ failure (predominantly renal failure) was responsible. When we excluded the cases in which the cause of death was not related to the burn, the Baux mortality prediction value improved (receiver operating characteristics area under the curve, AUC) from 0.9733 (95% CI 0.9633-0.9834) to 0.9888 (95% CI 0.9839-0.9936) and the sensitivity estimate increased from 45.2% to 53.9%.

    CONCLUSION: Patients with burns who died with a Baux score <100 were a quarter of all the patients who died. An important finding is that most of these deaths were caused by reasons other than the burn, usually cerebrovascular disease. This may be the explanation why the sensitivity of the Baux score is low, as factors other than age and TBSA % explain the fatal outcome.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keyword
    Baux score, Burns, Cause of death, Mortality
    National Category
    Cardiac and Cardiovascular Systems
    Identifiers
    urn:nbn:se:liu:diva-142898 (URN)10.1016/j.burns.2017.07.014 (DOI)28830698 (PubMedID)
    Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-09
  • Public defence: 2017-12-08 10:15 ACAS, Hus A, Linköping
    Uebel, Karl
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Conceptual Design of Complex Hydromechanical Transmissions2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis explores the conceptual design process of complex hydromechanical transmissions for mobile working machines. Efficient methods for design optimisation and controller development are presented to support the final concept selection.

    In the endeavour to develop new fuel-efficient driveline solutions for construction machines and off-road equipment new complex hydromechanical transmission concepts are being investigated. This pursuit is driven by stricter emission legislation, high fuel prices and a desire for a greener image both for customers and manufacturers. The trend towards more complex transmission architectures increases the need for more sophisticated product development methods. Complex multiple-mode transmissions are difficult to design and prototype and can be realised in a great number of architectures. By introducing a secondary energy storage in the machine the design space expands further for both hardware and software. There is accordingly a need for more reliable concept assessment in early design stages and the possibility to support concurrent engineering throughout the development process.

    Previous research on the design and development of hydromechanical transmissions has been limited to analysis of fixed concept designs or design optimization using very simple performance indicators. Existing methodologies for electrified on-road vehicles are not suitable for off-road working machines with hydromechanical transmissions and hydraulic energy storage.

    The proposed conceptual design process uses detailed quasi-static simulation models and targets to optimise the fuel efficiency of the specific machine specifications and operations. It is also shown how high-speed dynamic simulations can be used for controller development and hardware-in-the-loop simulations to support an efficient product design process. The methods are demonstrated for typical use cases targeting new transmission development for construction machines. Software control development is also treated using control optimisation and real-time simulation. Finally a novel hybrid hydromechanical motion system is presented for which an efficient design process is crucial to its end performance.

    List of papers
    1. Design Optimization of Complex Hydromechanical Transmissions
    Open this publication in new window or tab >>Design Optimization of Complex Hydromechanical Transmissions
    2013 (English)In: Journal of mechanical design (1990), ISSN 1050-0472, Vol. 135, no 9, 091005-1-091005-9 p.Article in journal (Refereed) Published
    Abstract [en]

    Demands for higher fuel efficiency for off-highway applications motivate manufacturers to replace existing drive transmissions with more complex, high-efficiency transmissions. Increased intelligence and more advanced architectures are, however, more difficult to design and prototype. This leads to longer product development processes and a greater need for early product evaluation. The great variety of existing concepts also requires a methodology to support the choice of architecture. This paper proposes a design methodology for complex hydromechanical transmissions based on optimization. The main objective is to maximize energy efficiency and adapt the design to suit the typical operating behavior of the application. The methodology is also implemented on a multiple mode transmission concept sui for a heavy wheel loader application. It is shown that the design of the gearbox heavily influences the energy consumption and the necessity to use optimization when designing the gearbox.

    Place, publisher, year, edition, pages
    ASME Press, 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-99379 (URN)10.1115/1.4024732 (DOI)000326172400006 ()
    Available from: 2013-10-17 Created: 2013-10-17 Last updated: 2017-11-09Bibliographically approved
    2. Optimisation and Concept Sensitivity of Continuously Variable Hydromechanical Transmissions
    Open this publication in new window or tab >>Optimisation and Concept Sensitivity of Continuously Variable Hydromechanical Transmissions
    2013 (English)Conference paper, Oral presentation only (Other academic)
    Abstract [en]

    Demands for better fuel efficiency for mobile working machines motivate the manufacturers to replace existing drive transmissions with more complex, high-efficiency transmissions. Hydromechanical power-split transmissions can offer high energy efficiency throughout the speed range and allows a decoupling of the speed of the combustion engine and the vehicle speed. This paper deals with the design of complex hydromechanical power-split transmissions and suggests an optimisation-based design methodology to minimise the energy consumption and manufacturing cost of the gearbox. The methodology is applied to a multiple mode power-split transmission which is designed to suit the requirements and typical operating behaviour of a heavy wheel loader. It is shown how important the design of the transmission is to its characteristics and how manufacturing costs can be weighed against energy efficiency.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-99380 (URN)
    Conference
    8th International Conference on Fluid Power Trans- mission and Control, April 9-11, Hangzhou, China
    Available from: 2013-10-17 Created: 2013-10-17 Last updated: 2017-11-09Bibliographically approved
    3. Modular Design of Hydromechanical Transmissions for Mobile Working Machines
    Open this publication in new window or tab >>Modular Design of Hydromechanical Transmissions for Mobile Working Machines
    2013 (English)In: Proceedings of the 13th Scandinavian International Conference on Fluid Power,(SICFP2013), June 3-5, 2013, Linköping, Sweden, Linköping: Linköping University Electronic Press, 2013, 113-119 p.Conference paper, Oral presentation only (Refereed)
    Abstract [en]

    This paper demonstrates an optimisation-based method to design modular gearboxes scalable for a range of applications. The design is adapted to the typical operating behaviours of the reference vehicles and considers the manufacturing costs of the gearboxes. Hydromechanical continuously variable transmissions (CVTs) are today strong candidates to replace drive line transmissions based on fuel-thirsty torque converters in many mobile working machines. The advantages include wide range of torque/speed ratios, high energy efficiency throughout the speed range and decoupling of the engine speed and the vehicle speed. Advanced multiple mode CVTs, however, are difficult to evaluate early in the product development process due to the complex architectures and the great variety of possible concepts. There is consequently an increased need for methods to design, compare and evaluate the transmission concepts. To decrease the development and manufacturing costs, there is also a need for scalable transmission concepts that can be used in several applications of different classes. The results show the proficiency of the methodology compared to a manual design process and that the energy efficiency of the transmissions are heavy coupled to the designs.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2013
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686 (print), 1650-3740 (online) ; 92
    Keyword
    Hydromechanical transmissions, Power-split, Design optimisation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-99381 (URN)10.3384/ecp1392a12 (DOI)978-91-7519-572-8 (ISBN)
    Conference
    Proceedings of the 13th Scandinavian International Conference on Fluid Power, (SICFP2013), June 3-5, 2013, Linköping, Sweden
    Available from: 2013-10-17 Created: 2013-10-17 Last updated: 2017-11-09Bibliographically approved
    4. Simulation Aided Design and Testing of Hydromechanical Transmissions
    Open this publication in new window or tab >>Simulation Aided Design and Testing of Hydromechanical Transmissions
    2014 (English)In: The 9th JFPS International Symposium on Fluid Power, Matsue, 2014, 2014Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper demonstrates the use of high-speed simulation in transmission conceptual design and presents a transmission test bed for hardware-in-the-loop simulations of hydromechanical transmission concepts. Complex transmissions, such as multiple-mode hydromechanical transmissions and hydraulic hybrid transmissions, present new difficulties and costs in the development process. There is today a greater demand for more efficient product development and more work has shifted towards simulation. The Hopsan simulation package allows robust, high-speed simulations suitable for both offline and hardware-in-the-loop simulation. New simulation models for hydromechanical transmissions are developed and used to simulate a known two-mode transmission concept. The same concept is also tested in hardware-in-the-loop simulations in the proposed transmission test bed. Results show good agreement with the hardware tests and highlight the proficiency of the simulation tools.

    Keyword
    Hydromechanical Transmission, Hardware-in-the-loop, Hopsan
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-126561 (URN)4-931070-10-8 (ISBN)
    Conference
    the 9th JFPS International Symposium on Fluid Power in Matsue, Shimane Japan, on October 28-31, 2014
    Available from: 2016-03-30 Created: 2016-03-30 Last updated: 2017-11-09
    5. Mode Shifting in Hybrid Hydromechanical Transmissions
    Open this publication in new window or tab >>Mode Shifting in Hybrid Hydromechanical Transmissions
    2015 (English)In: ASME/BATH 2015 Symposium on Fluid Power and Motion Control, ASME Press, 2015, 13- p.Conference paper, Published paper (Refereed)
    Abstract [en]

    Demands for low cost sustainable solutions have increased the use of and interest in complex hydromechanical transmissions for heavy off-road vehicles. In transmissions with multiplemodes, an important condition is to maintain the tractive force during the mode shifting event. For hybrid hydromechanical transmissions, with a direct connection to a hydraulic accumulator, the impressed system pressure caused by the hydraulic accumulator has not yet been observed to interfere with this condition. In this paper, a black box model approach is used to modify the hydraulic system after obtaining knowledge regarding how it is affected by a mode shift. A comparative study is carried out where a full vehicle model of a mobile working machine is simulated with two different hydraulic systems. The results show that different system solutions imply different demands on the included components, and that the mode shifting event is not a negligible factor in heavy hydraulic hybrid vehicles.

    Place, publisher, year, edition, pages
    ASME Press, 2015
    Keyword
    Mode shifting, hydromechanical transmissions, fluid power, heavy construction machinery
    National Category
    Other Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-126556 (URN)10.1115/FPMC2015-9583 (DOI)000373970500045 ()978-0-7918-5723-6 (ISBN)
    Conference
    ASME/BATH 2015 Symposium on Fluid Power and Motion Control, Chicago, Illinois, USA, October 12–14, 2015
    Projects
    Research on Hydromechanical Transmissions and Hybrid Motion systems, RHYTHM
    Funder
    Swedish Energy Agency, P39367-1
    Available from: 2016-03-30 Created: 2016-03-30 Last updated: 2017-11-09
    6. A novel hydromechanical hybrid motion system for construction machines
    Open this publication in new window or tab >>A novel hydromechanical hybrid motion system for construction machines
    2017 (English)In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 18, no 1, 17-28 p.Article in journal (Refereed) Published
    Abstract [en]

    This paper deals with a novel type of hybrid motion system for construction machines based on a common pressure rail shared between a hydromechanical power-split transmission and secondary controlled work hydraulics. A construction machine with driveline and work functions is a complex coupled motion system and the design of an effective hybrid system needs to take both subsystems into account. Studies on energy efficient hybrid systems for construction machines have hitherto principally focused on one subsystem at a time - work hydraulics or driveline. The paper demonstrates a use case with a specific transmission concept proposal for a medium-sized wheel loader. The system is modelled and simulated using an optimal energy management strategy based on dynamic programming. The results show the benefits of a throttle-free bidirectional link between the machine's subsystems and the energy storage, while taking advantage of the complex power flows of the power-split transmission.

    Place, publisher, year, edition, pages
    Abingdon, UK: Taylor & Francis, 2017
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-142329 (URN)10.1080/14399776.2016.1210423 (DOI)
    Available from: 2017-10-26 Created: 2017-10-26 Last updated: 2017-11-09Bibliographically approved
  • Nielsen, Isak
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Axehill, Daniel
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Low-Rank Modifications of Riccati Factorizations for Model Predictive Control2017In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, 1-8 p.Article in journal (Refereed)
    Abstract [en]

    In Model Predictive Control (MPC), the control input is computed by solving a constrained finite-time optimal control (CFTOC) problem at each sample in the control loop. The main computational effort when solving the CFTOC problem using an active-set (AS) method is often spent on computing the search directions, which in MPC corresponds to solving unconstrained finite-time optimal control (UFTOC) problems. This is commonly performed using Riccati recursions or generic sparsity exploiting algorithms. In this work the focus is efficient search direction computations for AS type methods. The system of equations to be solved at each AS iteration is changed only by a low-rank modification of the previous one, and exploiting this structured change is important for the performance of AS type solvers. In this paper, theory for how to exploit these low-rank changes by modifying the Riccati factorization between AS iterations in a structured way is presented. A numerical evaluation of the proposed algorithm shows that the computation time can be significantly reduced by modifying, instead of re-computing, the Riccati factorization. This speed-up can be important for AS type solvers used for linear, nonlinear and hybrid MPC.

  • Karlsson, Sofie
    et al.
    Linköping University, Department of Social and Welfare Studies.
    Sjöstedt, Jessica
    Linköping University, Department of Social and Welfare Studies.
    Det går inte att göra lika, det gör inte det även om man ska.: En kvalitativ studie om etnicitet och handlingsutrymme i familjehemsutredningar.2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med detta självständiga arbete är att undersöka hur etnicitet tillskrivs betydelse i utredningar avfamiljehem. Vidare vill vi undersöka hur familjehemssekreterarna beskriver sitt handlingsutrymme iutredningsarbetet. Syftet har besvarats med följande frågeställningar; (1) Hur aktualiseras etnicitet vidutredningar av familjehem? (2) Hur beskriver familjehemssekreterare sina erfarenheter avutredningsarbete av familjer med annan etnisk bakgrund än svensk? (3) Vilka utmaningar uppkommervid utredningar av familjer med en annan etnisk bakgrund än svensk? Socialstyrelsen anser att det finnsförbättringsåtgärder i familjehemsutredningar, främst gällande likvärdiga utredningsmodeller, men ävengällande den kompetensbrist som finns i socialt arbete vid bemötandet av utrikesfödda. I Sverige saknastidigare forskning kring familjehemsutredningar och etnicitet, det finns viss internationell forskning somfrämst utgår från adoption. De teoretiska utgångspunkter vi använt oss av är socialkonstruktionism,etnicitet som teoretiskt begrepp samt gräsrotsbyråkrati. Vi har genomfört en kvalitativ studie medsemistrukturerade intervjuer och intervjuat sex familjehemssekreterare och en enhetschef. När vianalyserade materialet kom vi slutligen fram till tre empiriska kategorier; Att behandla alla lika iutredningarna, idealfamilj samt utredningsdilemman. Resultatet visar att etnicitet aktualiseras tidigt iutredningsskedet när familjehemssekreterarna kategoriserar att familjen har en annan etnisk bakgrundän svensk. Efterföljande utredning skiljer sig från en utredning genomförd på en svensk familj, vid dessautredningar används en annan utredningsmodell. Familjehemssekreterarna beskriver och använder sitthandlingsutrymme på olika sätt vilket innebär att det skiljer sig mellan familjehemssekreterarnasutredningar av utrikesfödda familjer. De utmaningar som familjehemssekreterarna står inför ärframförallt likabehandling där organisationen säger att de ska behandla alla lika, medan familjernaförutsätter att de utreds efter sina individuella förutsättningar. En annan svårighet gällernätverksplaceringar där barnets anknytning väger tyngre än nätverkshemmets brister. Detta kan i vissafall bidra till en intressekrock mellan barnhandläggare och familjehemssekreterare därfamiljehemssekreterare får fatta beslut som strider mot riktlinjerna för när en familj ska bli godkänd.

  • Forsman, Isabelle
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Automatic LOD selection2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this paper a method to automatically generate transition distances for LOD, improving image stability and performance is presented. Three different methods were tested all measuring the change between two level of details using the spatial frequency. The methods were implemented as an optional pre-processing step in order to determine the transition distances from multiple view directions. During run-time both view direction based selection and the furthest distance for each direction was tested in order to measure the performance and image stability. The work was implemented in the Frostbite game engine and tested using data from DICE. The result is a method that generates transition distances by calculating the spatial frequency of the exclusive or comparison between the silhouette of a ground truth mesh and each level of detail. The transition distances generated using the automatic LOD selection tool was evaluated using visual empirical tests and performance measurements comparing the performance of a scene using automatic generated distances and manually selected distances. The tests shows that the resulting method produces good transition distances for meshes where the reduction is visible in the mesh silhouette. The values might need a bit of tweaking in order to account for other image artifacts than silhouette changes but provide a good guidance to the artists.

  • Göransson, Olof
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Nilsson, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A total cost analysis of reinforcement management2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    En totalkostnadsanalys som jämför två olika alternativ för armering. I första alternativet tillverkar företaget sin egen armering på ett lager för att sedan transportera ut armeringen till byggarbetsplatsen i färdiga armeringskorgar. I det andra alternativet beställs ILF (inläggningsfärdig armering) som levereras direkt till byggarbetsplatsen där den sedan knyta. Rapporten innehåller en beskrivande teoretisk referensram, noggrann beskriv av beräkningsgången samt analys och slutsatser utifrån resultaten i beräkningarna.

  • Alyusif, Natalee
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yacoub, Sally
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Cost comparison of alternative foundation methods2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    SAMMANFATTNING Syftet med detta projekt är att jämföra byggnaders olika grundläggningsmetoder, vid grundläggning på jordar med låg hållfasthet, för att kunna välja den mest ekonomiska metoden. I detta examensarbete har fokus lagts på fyra grundläggningsmetoder vilka är betongpålar, Kalkcement-pelare (KC-pelare), träpålar och stenpelare och deras respektive kostnadseffektivitet. Analysen baseras på utredning av hur företagets tid och kostnad påverkas i början av varje projekt samt vid användning av de olika grundläggningsmetoderna med fokus på olika faktorer som kan påverka valet av grundläggningsmetoder. Denna undersökning genomfördes genom att studera fyra projekt som utfördes av NCC anläggning och deras dotterföretag Hercules: tre av projekten är grundlagda med betongpålar och ett av projekten är grundlagt med stenpelare. Beräkningar innefattar projekteringskostnader och kostnad för utförande av de olika metoder där prisdokument fåtts av NCC anläggning och Hercules. Ett frågeformulär har skickats till två produktionschefer och en platschef som har arbetat med de olika metoderna för att få mer information från produktion. Dessutom samlades information från olika litteratur och hemsidor sökning för att förstå olika egenskaper hos varje metod Slutsatsen av detta arbete ät att den mest ekonomiska grundläggningsmetoden är betongpålar samt den är mest användbara hos NCC, medan stenpelare är den dyraste metoden som har använts bara en gång av NCC anläggning. Dessutom fick vi antagande projekt om KC-pelare som visas vara dyrt metod jämförd med betongpålar. Därtill har inte fått något projekt om träpålar, därför är det svårt att undersöka den metoden.

  • Larsson, Per
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Mahmoud, Bawan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Work environment and safety on the construction site - a matter of mindset2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • Benjaminsson, Amanda
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Gustavsson, Amanda
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Project management in a digitalized contruction industry - A study about the challenges and effects of implementation of VDC among project leaders2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Samhället blir alltmer digitalt, men den svenska byggbranschen har inte hängt med lika bra i den pågående digitaliseringen som andra branscher. Det kommer att ligga mycket ansvar på projektledarna i byggprojekten om branschen ska kunna möta de nya utmaningar som uppstår i och med digitaliseringsprocessen. I dagsläget saknas utredningar kring hur digitaliseringen med projektmodellen Virtual Design and Construction (VDC) bättre kan utnyttjas av projektledande konsulter i byggbranschen. Denna studie har därför som syfte att undersöka hur projektledande konsultföretag kan anpassa sig till och utnyttja möjligheterna med VCD för att planera och styra projekt. För att utföra undersökningen formulerades frågeställningar gällande vad VDC innebär för projektledare, hur användningen ser ut idag och vilka utmaningar som måste hanteras för att öka användningen. Frågeställningarna besvarades genom en litteraturstudie och halvstrukturerade intervjuer med medarbetare på Sweco Management i Östergötland, följt av en analys av resultaten. De åtta respondenterna som intervjuades arbetade alla som projektledare. Ämnen som togs upp under intervjuerna handlade om projektledarens roll i byggprocessen, hur respondenterna arbetade med VDC och Building Information Modeling (BIM), vilka effekter de observerat att digitaliseringen har gett samt vilka utmaningar och hinder de upplevde fanns för att implementeringen av VDC skulle lyckas. Få av respondenterna kände att de kunde förklara vad VDC och BIM innebar då de sällan kom i kontakt med begreppen i vardagen. De kände att de hade begränsat med kunskap kring begreppen och att det var svårt att finna tid till att utbilda sig i ämnet. Utifrån intervjuerna drogs slutsatserna att tre utmaningar måste hanteras för att projektledare ska kunna öka sin användning av VDC: kunskapsnivån kring VDC hos projektledare är i dagsläget låg och bör höjas, byggbranschen måste enas om en gemensam definition av begreppet BIM och en relation mellan konsultföretag och deras beställare, som möjliggör utvecklingen av ett samarbete kring utbildning, behöver inledas.

  • Khabiri, Behnam
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Environmental certifications Miljöbyggnad & Svanen Ecolabelling of a multi-family house and a comparison of the indoor environment2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    I dagens samhälle har det blivit allt vanligare med miljöfrågor och detta har påverkat byggbranschen kraftigt. Eftersom miljöbyggnad ger en bättre levnadskvalité, miljö samt billigare drift så har allt fler byggherrar attraherats till det och ändrat på branschens synvinkel. Syftet med studien var att undersöka miljöcertifiering Miljöbyggnad Silver och Svanen för ett flerbostadshus samt en jämförelse mellan systemen med hänsyn till inomhusmiljön. Metoden för insamling av information har varit litteraturstudie och baseras för det mesta på de olika manualer som har lagts upp av SGBC samt Svanen. En noggrann undersökning av Svanens och Miljöbyggnads kriterier har utförts samt relevant information har valts ut. Prövningen för ett flerbostadshus för miljöcertifieringen Miljöbyggnad görs på tre olika områden energi, innemiljö och material. Undersökningar har gjorts och tabeller har tagits fram som visar hur ett flerbostadshus kan uppnå betyget Silver. Den sammanlagda Betyget på de olika indikatorer, aspekter och områden ger byggnadens slutgiltiga betyg. Prövningen för ett flerbostadshus för miljöcertifieringssystemet Svanen görs genom Svanens 41 obligatoriska krav samt ett poängsystem där 17 av de 44 poängen ska vara uppfyllda. Resultatet av studien visar att det krävs en bra planering för att ett flerbostadshus ska uppnå miljöcertifiering Miljöbyggnad Silver eller Svanen. En jämförelsetabell har tagits fram och det visar sig att de två olika certifieringssystemen har många likheter när det kommer till inomhusmiljökriterier men det finns även markant differentierade kravspecifikationer.

  • Johansson, Emil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Johansson, Viktor
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The choice of soil improvement at railroad constructions2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Vid byggnation av järnväg måste man som projektör ta hänsyn till om marken behöver förstärkas eller ej. Detta gör att man står inför viktiga avväganden vid valet av jordförstärkningsmetod. Studiens syfte har varit att skapa ett förtydligande underlag för beslutsprocessen med avseende på bankpålning och kalkcementpelare ur en teknisk- och en ekonomisk synvinkel. Den tekniska jämförelsen utfördes genom att studera vår litteraturstudien och ur denna valdes 14 parametrar för att utvärdera de respektive metoderna. Den ekonomiska frågeställningen besvarades genom att utföra en fallstudie. Vid anläggning av järnväg måste funktion gå före kostnad. Detta medför att man sällan står i en avvägning mellan kalkcementpelare och bankpålning. Metoderna går inte att använda på samma sätt och beroende på jordens egenskaper och belastning skall metod väljas. Men för att ta det beslutet krävs det att noggranna geotekniska undersökningar har genomförts.

  • Egerud, Rebecca
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Södergren, Erik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Cost differences between Miljöbyggnad Guld and BBR2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Denna rapport är en jämförelse mellan BBR och Miljöbyggnad nivå Guld. Tre frågeställningar besvaras, Vad är skillanden mellan BBR och Miljöbyggnad nivå guld, vad är mervärdet och merkostnaden av Miljöbyggnad nivå Guld. Studien är utförd på en fallstudie av Studenthuset som byggs på Linköpings Universitet. Resultaten av studien visar att skillanderna mellan de två är stora, mervärdet för Miljöbyggnad nivå Guld är stort samt att merkostnaden är 2.5 - 3.0 % för Miljöbyggnad nivå GUld

  • Arping, Christopher
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Bergman, Karl
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The difference between the calculated cost and the actual cost with focus on concrete slab2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Denna studie är ett examensarbete och det avslutande momentet inom utbildningen byggteknik på Linköpings Universitet, campus Norrköping. Examensarbetet fokuserar på att ta reda på och kartlägga kostnadsavvikelser mellan kalkylerade och verkliga byggkostnader. Bakgrunden till studien ligger i att båda författarna har erfarenheter från byggbranschen och vet att kostnadsutfallet för projekt inte alltid blir som planerat. Därför togs beslutet att djupare analysera om vad orsakerna till avvikelser kan bero på. Syftet med studien är att undersöka om möjliga avvikelser finns mellan kalkyler och verkliga byggkostnader samt finna orsaker och åtgärder till avvikelserna. För att framställa ett resultat till studien ställdes tre övergripande frågeställningar som hela arbetet strävar efter att besvara. Dessa är “hur ser kalkyleringsprocessen ut?”, “vilka kostnadsavvikelser finns mellan kalkylerade och verkliga byggkostnader?” och “hur åtgärdas eventuella avvikelser?”. Arbetet har genomförts genom projektuppföljning för tre projekt hos ett företag där kostnader jämförts mellan anbudskalkylen och det verkliga utfallet för projektet. Studien tar endast hänsyn till projektkostnaden vilket innebär att det begränsas genom att inte räkna med centraladministration och vinst vilket anbudssumman annars också består av. Orsaker till avvikelser har fastställts via intervjuer med platscheferna för respektive projekt. Resultatet som uppnåtts visar på att avvikelser förekommer relativt ofta och främst på grund av ett fåtal orsaker. De poster som visar störst avvikelser genomgående i alla tre projekt är armering/ingjutningsgods, isolering, betong och arbetsplatsomkostnader. De största orsakerna till negativa avvikelser visade sig vara kalkyleringsfel, svåra arbetsplatsförhållanden och dåligt utfört arbete av underentreprenörer. Största orsakerna till att positiva avvikelser uppstått berodde på prutat pris för inköp samt ändrade arbetsmetoder. Det studien kommit fram till är att företaget bör skapa bättre rutiner för erfarenhetsåterföring från yrkesarbetare till kalkylarbetare. Ett annat förbättringsförslag är att även bli bättre på att besöka den tänkta arbetsplatsen innan start av kalkylering. Detta för att förebygga att avvikelserna uppstår i framtida projekt.

  • Bihagen, Jennifer
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Johnsson, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Productivity in construction production for wheel excavators2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Byggbranschen har en låg produktivitetsutveckling i jämförelse med andra industribranscher. Den låga produktivitetsnivån medför stora kostnader för byggföretagen. För att vända trenden krävs det en kartläggning av nuvarande produktivitet för att sedan kunna genomföra en förändring. Ett nytt verktyg för att mäta produktivitet för maskiner ska införas hos Skanska AB och i denna studie utförs mätningen på grävmaskiner på hjul i ett vägprojekt. Mätningen går till så att en produktivitetsmätare placeras på en grävmaskin. Mätaren registrerar rörelse och skickar data till en server som sedan gör om indata till rapporter. Studien har tre syften: det första är att kartlägga normalläget av rörelse för grävmaskiner på hjul, det andra är att ta reda på varför grävmaskinerna inte utnyttjas till högre grad och det sista är hur produktivitetsmätning av grävmaskiner kan minska graden av stillastående inom byggproduktion. De metoder som använts är objektiv mätning, intervjuer och dagböcker. Normalläget av rörelse identifieras till 72–73% för grävmaskinerna i projektet som studien utförts vid. Detta är alltså ett stillestånd på 27–28%. Målet är 0% stillestånd men ett riktvärde att uppnå är 20–25%. Det finns olika typer av stillestånd, de som är planerade och de som är oplanerade. Det som är mest intressant i denna studie är de oplanerade. De vanligaste orsakerna till oplanerade stillestånd uppges vara brister i planeringen, oväntade fel såsom maskinhaveri och sjukdom. Anledningar till planerade stillestånd är ledighet, möten och raster. För att förbättra produktiviteten, minska slöseri och stillestånd av arbetstid för grävmaskiner kan de värden som fås från produktivitetsmätarna användas som en punkt i veckomöten där orsaker bakom data diskuteras. Det blir då en naturlig del av mötet att prata om produktiviteten.  

  • Källstrand, Ellen
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Pucar, Nina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Comparison of various wooden facades2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Gran och tall är de vanligaste barrträden i Sverige. Tack vare import från andra länder har kontakt med andra träslag som inte växer i Sverige uppstått. Dessa nya träslag väcker ett intresse att vilja skapa fasader med de nya träslagen. Studiens syfte är att jämföra behandlade träfasader med två obehandlade ädelträslag gällande kostnad och beständighet. Behandlingarna som har studerats är järnvitriol samt akrylatfärg och ädelträslagen som valts är jättetuja (Thuja Plicata) och sibirisk lärk (Larix Sibirica). Då det vanligaste underlaget för akrylatfärg är gran och furu har även dessa träslag behandlats i rapporten. Målet är att komma fram till vilket ädelträ som är mest lämpligt i förhållande till en behandlad fasad. Studien har genomförts genom att studera litteratur och dokument samt intervjua en arkitekt, en bebyggelseantikvarie, en forskare, en färghandlare och en produktchef från en träleverantör. Respondenternas svar vid intervjuerna behandlar bland annat osäkerheten vid att använda ett relativt nytt träslag i Sverige som fasad. Flera av dem tar även upp att en obehandlad träfasad kommer att få färgförändringar med tiden och det är svårt på att förhand veta vilken färg fasaden kommer att anta och om den åldras jämnt. Järnvitriol är en behandling som ger träet ett väderpinat uttryck snabbare än den naturliga patineringen. Dock skyddar behandlingen inte träet till skillnad från akrylatfärgen som ger träet ett extra skydd mot yttre påverkan. Skillnaden mellan ceder och lärk är stor i vissa avseenden, bland annat är det ena träslaget mer sprickbenäget och har kortare livslängd. Fördelen med en obehandlad träfasad, jämfört med en fasad målad med akrylatfärg, är att en rätt konstruerad obehandlad träfasad kräver väldigt lite underhåll till skillnad från akrylatfärgens underhållsintervall på 10–15 år. Kostnadsmässigt är det ganska stor skillnad beroende på vilken typ av fasad som väljs. Det viktiga för en träfasad är att den får möjlighet att torka ut ordentligt efter nederbörd. Ett takutsprång är även en fördel både vad gäller en behandlad och obehandlad fasad. Träslagen rapporten behandlar är alla lämpliga att använda som fasad men då de har olika egenskaper passar behandlingarna olika bra med respektive träslag.

  • Hafström, Johan H
    et al.
    Institutionen för Informationsteknologi och Systemvetenskap, Högkolan i Östersund.
    Nordström, Malin
    Institutionen för Informationsteknologi och Systemvetenskap, Högkolan i Östersund.
    Systemförvaltning: faktisk verksamhet, problem och möjligheter1991Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim with the present work is to examine how corporations and organizations maintain their information systems, if the Applied Mode! (Hafström, Nordström; 1991) contain all parts required for working system maintenance and according to this discuss problems and possibilities of system maintenance. We realized a literature study and interviewed people who are involved in the process of system maintenance. The result of the literature study is presented by definitions of conceptions and the result of three examinations. A summary of the interviews is made. From the received information we developed the definition of the system maintenance conception. Applied Mode! is developed and the result is Rocket Maintenance Model. Further on we discuss problems and possibilities of system maintenance and finally we are giving our opinion how to start the work by structuring the system maintenance process.

  • Gustafsson, Torsten
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Concepts of Hybrid Data Rendering2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes methods for advanced visualization of 3D data. Order-independent transparent data between multiple datasets of varying types can be combined using an A-buffer. In this thesis, an implementation of such a buffer is presented. An optimisation of the A-buffer, based on the discarding of unnecessary fragments will be presented. A line integral convolution method for 3D volumes will also be presented, where noise input, and resolution of the input- compared to output volumes will be discussed. The resulting method is able to visualize multiple types of data with order-independent transparency. The rendering speed is generally fast enough for an interactive user-experience.

  • Henriksson, Fredrik
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    Introducing New Materials in the Automotive Industry: Managing the Complexity of Introducing New Materials in Existing Production Systems2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Passenger vehicles are central to Western society, and contribute to a significant part of our greenhouse gas emissions. In order to reduce emissions, the automotive industry as a whole is working to reduce mass in passenger vehicles in order to reduce energy consumption. One way to reduce mass is to introduce lightweight materials in the body of the vehicle. This research aims to explore the relationship between product and production system when introducing new materials.

    Besides a theoretical review and an industry-centered technological mapping, four case studies have been conducted during the course of this licentiate thesis. Two case studies were conducted with engineering design students working as development teams, one case study with the author as the developer and finally one case study in an industrial environment at a product owning company with in-house production. The goal of the case studies has been to increase the collective knowledge of how product development decisions affect production development decisions, and vice versa, when developing passenger vehicles in new materials.

    In the following analysis of case study outcomes, a number of factors important for introducing new materials are discussed. The relationship between product and production is investigated, both in terms of how the production system affects the product and how the product affects the production system. The outcome from this analysis is a mapping of important factors for automotive industry companies to understand and identify when looking at introducing new materials in existing production systems. Finally, a suggestion for future research efforts is presented.

    List of papers
    1. An outlook on multi material body solutions in the automotive industry – possibilities and manufacturing challenges
    Open this publication in new window or tab >>An outlook on multi material body solutions in the automotive industry – possibilities and manufacturing challenges
    2016 (English)In: SAE Technical Paper Series, Detroit (MI), USA: Society of Automotive Engineers, 2016Conference paper, Published paper (Refereed)
    Abstract [en]

    In the automotive industry, mass reduction and lightweight design is a continuing trend that does not show signs of declining. When looking at where to reduce weight in a vehicle, the body is a preferential subsystem due to its large contribution to overall mass and the stability of body composition over a specific model range. The automotive industry of today moves toward a greater differentiation in materials that compose a car, which can be seen in the several different multi material vehicle bodies that have been introduced by manufacturers in recent years. But while mixing materials may contribute to a good compromise between weight reduction and vehicle cost, it also proposes a number of challenges that need to be addressed. Among other material factors, the different coefficients of thermal expansions might introduce new stresses during painting and curing. Joining processes and possible chemical reactions between materials also needs to be taken into account, the same with the question of whether to integrate or differentiate different functions in a system. If the manufacturing plant uses mixed model assembly lines, design of end effectors for gripping multiple different materials is another challenge not previously encountered in this context. In this paper, a number of production and manufacturing related challenges are discussed, and the authors highlight different areas where the requirements of design engineering tools needs to be evaluated for these new multi material concepts and design decisions in order for automotive manufacturers to ensure future market competitiveness.

    Place, publisher, year, edition, pages
    Detroit (MI), USA: Society of Automotive Engineers, 2016
    Keyword
    Multi material bodies, Production development, Product development
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-127319 (URN)10.4271/2016-01-1332 (DOI)
    Conference
    SAE 2016 World Congress and Exhibition
    Projects
    Produktion2030 - Storskalig tillverkning av produkter i flera material
    Funder
    VINNOVA
    Available from: 2016-04-20 Created: 2016-04-20 Last updated: 2017-11-08Bibliographically approved
    2. On Material Substitution in Automotive BIWs – From Steel to Aluminum Body Sides
    Open this publication in new window or tab >>On Material Substitution in Automotive BIWs – From Steel to Aluminum Body Sides
    2016 (English)In: 26TH CIRP DESIGN CONFERENCE / [ed] Wang, Lihui; Kjellberg, Torsten, Elsevier, 2016, Vol. 50, 683-688 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    Weight reduction and material substitution are increasing trends in the automotive industry. In this project, the task of substituting the steel body side in the monocoque of a large SUV towards an aluminum body side was investigated through a design engineering approach adopting a breadth-first analysis method. One conclusion based on the analysis is that the choice of joining technology would become arbitrary due to the breadth-first approach. In this paper, the authors present their findings from the aforementioned case, including the challenges with switching between materials with fundamentally different properties when performing material substitution projects. The possibility of having taken a depth-first analysis approach, and the possible effects on the project result, is discussed.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Series
    Procedia CIRP, ISSN 2212-8271 ; 50
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-130510 (URN)10.1016/j.procir.2016.05.028 (DOI)000387666600115 ()
    Conference
    26th CIRP Design Conference
    Projects
    Produktion 2030 - Storskalig tillverkning av produkter i flera material
    Funder
    VINNOVA
    Available from: 2016-08-11 Created: 2016-08-11 Last updated: 2017-11-08
    3. Including Student Case Projects in Integrated Product and Production Development Research – Methodology Description and Discussion
    Open this publication in new window or tab >>Including Student Case Projects in Integrated Product and Production Development Research – Methodology Description and Discussion
    2016 (English)Conference paper, Oral presentation only (Other academic)
    Abstract [en]

    Within integrated product and production development research, casestudies needto be performed for data gathering purposes. Today, there are two commonly used ways to perform this research; observingindustry projects orhaving the researchers perform the projects themselves. The first option can pose data access and IPRissues, and the second optioncomes with biasing risks. Another approach is to work with studentcaseprojects, givingstudents interesting projects and findinga solution to mediate both data gathering opportunity and biasing risks. This approach has been tested at Linköping University, with students performing projects in the Vinnovafunded Production 2030 –Large Scale Production in Mixed Materials project. Two larger student case projects have been performed on the topic of material substitution and mixed material solutions within the automotive industry.In this paper, the method used to include student projects is presented along with identified benefits and drawbacks. Including student case projects in research have shown to be beneficial in research on processes, projects and methodology, but needs to be complemented by data fromindustry projects and the researcher ́s own work within integrated product and production development in order to create a more reliable analysis with high level of detail.

    Keyword
    Case studies, Integrated product and production development, mixed material solutions
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-142930 (URN)
    Conference
    7th Swedish Production Symposium, SPS, Lund, October 25-27, 2016
    Funder
    VINNOVA
    Note

    Fulltexten i denna post har endast gjorts tillgänglig via DiVA.

    The full text of this entry has only been made available via DiVA.

    Available from: 2017-11-13 Created: 2017-11-13 Last updated: 2017-11-20
  • Public defence: 2017-11-30 13:15 Hugo Theorell, Linköping
    Lundengård, Karin
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Mechanistic modelling - a BOLD response to the fMRI information loss problem2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Functional Magnetic Resonance Imaging (fMRI) is a common technique for imaging brain activity in humans. However, the fMRI signal stems from local changes in oxygen level rather than from neuronal excitation. The change in oxygen level is referred to as the Blood Oxygen Level Dependent (BOLD) response, and is connected to neuronal excitation and the BOLD response are connected by the neurovascular coupling. The neurons affect the oxygen metabolism, blood volume and blood flow, and this in turn controls the shape of the BOLD response. This interplay is complex, and therefore fMRI analysis often relies on models. However, none of the previously existing models are based on the intracellular mechanisms of the neurovascular coupling. Systems biology is a relatively new field where mechanistic models are used to integrate data from many different parts of a system in order to holistically analyze and predict system properties. This thesis presents a new framework for analysis of fMRI data, based on mechanistic modelling of the neurovascular coupling, using systems biology methods.

     Paper I presents the development of the first intracellular signaling model of the neurovascular coupling. Using models, a feed-forward and a feedback hypothesis are tested against each other. The resulting model can mechanistically explain both the initial dip, the main response and the post-peak undershoot of the BOLD response. It is also fitted to estimation data from the visual cortex and validated against variations in frequency and intensity of the stimulus. In Paper II, I present a framework for separating activity from noise by investigating the influence of the astrocytes on the blood vessels via release of vasoactive sub- stances, using observability analysis. This new method can recognize activity in both measured and simulated data, and separate differences in stimulus strength in simulated data. Paper III investigates the effects of the positive allosteric GABA modulator diazepam on working memory in healthy adults. Both positive and negative BOLD was measured during a working memory task, and activation in the cingulate cortex was negatively correlated to the plasma concentration of diazepam. In this area, the BOLD response had decreased below baseline in test subjects with >0.01 mg/L diazepam in the blood. Paper IV expands the model presented in Paper I with a GABA mechanism so that it can describe neuronal inhibition and the negative BOLD response. Sensitization of the GABA receptors by diazepam was added, which enabled the model to explain how changes to the BOLD response described in Paper III could occur without a change in the balance between the GABA and glutamate concentrations.

    The framework presented herein may serve as the basis for a new method for identification of both brain activity and useful potential biomarkers for brain diseases and disorders, which will bring us a deeper understanding of the functioning of the human brain.

    List of papers
    1. Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI
    Open this publication in new window or tab >>Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI
    Show others...
    2016 (English)In: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 12, no 6, e1004971Article in journal (Refereed) Published
    Abstract [en]

    Functional magnetic resonance imaging (fMRI) measures brain activity by detecting the blood-oxygen-level dependent (BOLD) response to neural activity. The BOLD response depends on the neurovascular coupling, which connects cerebral blood flow, cerebral blood volume, and deoxyhemoglobin level to neuronal activity. The exact mechanisms behind this neurovascular coupling are not yet fully investigated. There are at least three different ways in which these mechanisms are being discussed. Firstly, mathematical models involving the so-called Balloon model describes the relation between oxygen metabolism, cerebral blood volume, and cerebral blood flow. However, the Balloon model does not describe cellular and biochemical mechanisms. Secondly, the metabolic feedback hypothesis, which is based on experimental findings on metabolism associated with brain activation, and thirdly, the neurotransmitter feed-forward hypothesis which describes intracellular pathways leading to vasoactive substance release. Both the metabolic feedback and the neurotransmitter feed-forward hypotheses have been extensively studied, but only experimentally. These two hypotheses have never been implemented as mathematical models. Here we investigate these two hypotheses by mechanistic mathematical modeling using a systems biology approach; these methods have been used in biological research for many years but never been applied to the BOLD response in fMRI. In the current work, model structures describing the metabolic feedback and the neurotransmitter feed-forward hypotheses were applied to measured BOLD responses in the visual cortex of 12 healthy volunteers. Evaluating each hypothesis separately shows that neither hypothesis alone can describe the data in a biologically plausible way. However, by adding metabolism to the neurotransmitter feed-forward model structure, we obtained a new model structure which is able to fit the estimation data and successfully predict new, independent validation data. These results open the door to a new type of fMRI analysis that more accurately reflects the true neuronal activity.

    Place, publisher, year, edition, pages
    PUBLIC LIBRARY SCIENCE, 2016
    National Category
    Bioinformatics (Computational Biology)
    Identifiers
    urn:nbn:se:liu:diva-130437 (URN)10.1371/journal.pcbi.1004971 (DOI)000379349700045 ()27310017 (PubMedID)
    Note

    Funding Agencies|Swedish Research council [2014-6249]; Knut and Alice Wallenbergs foundation, KAW [2013.0076]; Research council of Southeast Sweden [FORSS-481691]; Linkoping University

    Available from: 2016-08-06 Created: 2016-08-05 Last updated: 2017-11-08
    2. Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex
    Open this publication in new window or tab >>Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex
    Show others...
    2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3Article in journal (Refereed) Published
    Abstract [en]

    Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD) responses in functional magnetic resonance imaging (fMRI) is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

    Place, publisher, year, edition, pages
    San Francisco, CA, United States: Public Library of Science, 2016
    Keyword
    quantitative magnetic resonance imaging; brain tissue modeling; myelin; edema; T-1 relaxation; T-2 relaxation; proton density
    National Category
    Neurosciences
    Identifiers
    urn:nbn:se:liu:diva-126192 (URN)10.1371/journal.pone.0148737 (DOI)000371434500011 ()26930498 (PubMedID)
    Note

    Funding agencies: Linkoping University; County Council of Ostergotland

    Available from: 2016-03-18 Created: 2016-03-18 Last updated: 2017-11-08Bibliographically approved