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  • 1.
    Lofgren, PM
    et al.
    ABB Corp Res, SE-72178 Vasteras, Sweden Royal Inst Technol, Faxen Lab, SE-10044 Stockholm, Sweden Linkoping Univ, IFM, SE-58183 Linkoping, Sweden.
    Hallin, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Gu, CY
    ABB Corp Res, SE-72178 Vasteras, Sweden Royal Inst Technol, Faxen Lab, SE-10044 Stockholm, Sweden Linkoping Univ, IFM, SE-58183 Linkoping, Sweden.
    Ji, W
    ABB Corp Res, SE-72178 Vasteras, Sweden Royal Inst Technol, Faxen Lab, SE-10044 Stockholm, Sweden Linkoping Univ, IFM, SE-58183 Linkoping, Sweden.
    3-d thermal and flow modeling of hot wall epitaxial chemical vapor deposition reactors, heated by induction2000In: Materials Science Forum, ISSN 0255-5476, Vol. 338-3, 153-156 p.Article in journal (Refereed)
    Abstract [en]

    A three dimensional computational model for temperature and flow predictions in hot wall chemical vapor deposition (CVD) reactors, heated by induction, is presented. It includes heating by a Radio Frequency (RF) coil, flow and heat transfer. Thermal radiation is modeled by a modified Monte Carlo method. Model predictions are compared to full scale experiments at Linkoping CVD reactor for epitaxial growth of silicon carbide (SIC). Both streamwise and spanwise temperature gradients are well predicted, with the temperature maximum location shifted slightly upstream compared to the measured. Additionally, the model succeeds in predicting a recirculation zone just downstream of the susceptor. It is demonstrated how thermal gradients can be greatly reduced by simple geometrical changes.

  • 2.
    Kurahashi, Yuko
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Herbertsson, Helena
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Söderström, Mats
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Rosenfeld, Michael G
    University of California, San Diego, La Jolla, CA, USA.
    Hammarström, Sven
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    A 12(S)-hydroxyeicosatetraenoic acid receptor interacts with steroid receptor coactivator-12000In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 97, no 11, 5779-5783 p.Article in journal (Refereed)
    Abstract [en]

    Lewis lung carcinoma cells contain specific high-affinity binding sites for the eicosanoid 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid [12(S)-HETE]. These binding sites have a cytosolic/nuclear localization and contain the heat shock proteins hsp70 and hsp90 as components of a high molecular weight cytosolic binding complex. The ligand binding subunit of this complex is a protein with an apparent molecular mass of ÿ50 kDa as judged by gel permeation chromatography. In this report, we present data showing that the 50-kDa 12(S)-HETE binding protein interacts as a homodimer with steroid receptor coactivator-1 (SRC-1) in the presence of 12(S)-HETE. Two putative interaction domains were mapped. One of these (amino acids 701-781) was within the nuclear receptor interaction domain in SRC-1 required for binding of various steroid and thyroid hormone receptors. It contains the most C-terminal of the three copies of LXXLL motif present in the nuclear receptor interaction domain. The second interaction domain was present in the N-terminal part of SRC-1 (amino acids 1-221). This region has two LXXLL motifs, one does not bind and the other binds only weakly to steroid and thyroid hormone receptors. Glutathione S-transferase (GST) pulldown experiments and far Western analyses demonstrated that the N-terminal region of SRC-1 (amino acids 1-212) alone does not bind the 50-kDa 12(S)-HETE binding protein, whereas GST/?SRC-11-1138 ligand-dependently pulled down a protein of ÿ50 kDa in size. Our results suggest that the 50-kDa 12(S)-HETE binding protein is a receptor that may signal through interaction with a nuclear receptor coactivator protein.

  • 3.
    Roy, Chandan
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    A biologically based machine learning approach to tropical cyclone intensity forecastingManuscript (preprint) (Other academic)
    Abstract [en]

    A biologically based ANN using four hierarchical levels, is trained and tested using temporal sequences of 2D inputs to forecast Tropical Cyclone (TC) intensity12, and 24 hours ahead in the Atlantic basin. We use five parallel input layers to feed infrared, ocean heat content, sea-level pressure, wind direction and wind speed images into the network. Forecasts are produced in the Saffir-Simpson hurricane intensity scale and are compared to the observed wind speeds in the TC best track data on two separate test datasets for validation. Forecasting accuracy is more than 95% for the test dataset containing temporal continuations of the TC lifecycle time-step images that are excluded from training, whereas, forecasting accuracy is between 30% and 55%, when images of a novel TC are used for testing. This result reveals that biologically inspired ANNs have a potential to be further developed into an effective TC intensity forecasting technique.

  • 4.
    Johansson, Kajsa
    et al.
    Linköping University, Department of Medicine and Health Sciences, Physiotherapy. Linköping University, Faculty of Health Sciences.
    Öberg, Birgitta
    Linköping University, Department of Medicine and Health Sciences, Physiotherapy. Linköping University, Faculty of Health Sciences.
    Adolfsson, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Orthopaedics and Sports Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Orthopaedic Centre, Department of Orthopaedics Linköping.
    Foldevi, Mats
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Central County Primary Health Care.
    A combination of systematic review and clinicians’ beliefs in interventions for subacromial pain2002In: British Journal of General Practice, ISSN 0960-1643, Vol. 52, no 475, 145-152 p.Article in journal (Refereed)
    Abstract [en]

    The aim of the study is to determine which treatments for patients with subacromial pain are trusted by general practitioners (GPs) and physiotherapists, and to compare trusted treatments with evidence from a systematic critical review of the scientific literature. A two-step process was used: a questionnaire (written case simulation) and a systematic critical review. The questionnaire was mailed to 18 GPs and 71 physiotherapists in Sweden. The total response rate was 72% (186/259). The following treatments were trusted: ergonomics/adjustments at work, corticosteroids, non-steroidal anti-inflamatory drugs, movement exercises, acupuncture, ultrasound therapy, strengthening exercises, stretching, transcutaneous electric nerve stimulation, and superficial heat or ice therapy. The review, including efficacy studies for the treatments found to be trusted, was conducted using the CINAHL, EMBASE and MEDLINE databases. Evidence for efficacy was recorded in relation to methodological quality and to diagnostic criteria that labelled participants as having subacromial pain or a non-specific shoulder disorder. Forty studies were included. The methodological quality varied and only one treatment had definitive evidence for efficacy for non-specific patients, namely injection of corticosteroids. The trust in corticosteroids, injected in the subacromial bursa, was supported by definitive evidence for short-term efficacy. Acupuncture had tentative evidence for short-term efficacy in patients with subacromial pain. Ultrasound therapy was ineffective for subacromial pain. This is supported by tentative evidence and, together with earlier reviews, this questions both the trust in the treatment and its use. The clinicians' trust in treatments had a weak association with available scientific evidence.

  • 5.
    Eriksson, Ola
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    A comparison between in vitro studies of protein lesions generated by brain electrodes and finite element model simulations1999In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 37, no 6, 737-741 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop a finite element model for simulation of the thermal characteristics of brain electrodes and to compare its performances with an in vitro experimental albumin model. Ten lesions were created in albumin using a monopolar electrode connected to a Leksell Neuro Generator and a computer-assisted video system was used to determine the size of the generated lesions. A finite element model was set up of the in vitro experiments using the same thermal properties. With a very simple heat source applied to the finite element model in the proximity of the upper part of the tip, a good agreement (no deviations in width and distance from tip but a deviation in length of −1.6 mm) with the in vitro experiments (width 4.6±0.1 mm and length 7.4±0.1 mm) was achieved when comparing the outline of the lesion. In addition, a gelatinous albumin-model was set up and compared to computer simulations resulting in deviations in width of −0.4 mm, length of −2.2 mm and distance from the tip of −0.1 mm. Hence, the utilisation of finite element model simulations may be a useful complement to in-vitro experiments.

  • 6.
    Esamai, Fabian
    et al.
    Department of Child Health and Paediatrics, Faculty of Health Sciences, Moi University, Eldoret, Kenya.
    Mining, Simeon
    Department of Child Health and Paediatrics, Faculty of Health Sciences, Moi University, Eldoret, Kenya.
    Forsberg, Pia
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Lewis, David H.
    A comparison of brain, core and skin temperature in children with complicated and uncomplicated malaria2001In: Journal of Tropical Pediatrics, ISSN 0142-6338, E-ISSN 1465-3664, Vol. 47, no 3, 170-175 p.Article in journal (Refereed)
    Abstract [en]

    A prospective study was carried out in which brain, core and skin temperatures were studied in children with cerebral malaria (n = 23), uncomplicated malaria (n = 12) and normal children (n = 9) using the zero heat flow method. Patients with cerebral or uncomplicated malaria were admitted to the paediatric wards (mean age, 6 years 8 months ± 2 years 8 months). Normal children, children of the investigators, of the same age group, served as controls. Parasitaemia levels were similar in the cerebral and uncomplicated malaria cases. Higher brain than core temperatures would have been expected in cerebral malaria but not in uncomplicated malaria but this was not the case in this study. There was no statistical difference in brain, core and skin temperature between cerebral and uncomplicated malaria patients. However, there was a highly significant difference between normal children and cerebral and uncomplicated malaria patients. Brain temperature was 0.02–0.2°C below core temperature in all the groups with larger differences during the febrile period. Mean differences of brain minus core, brain minus skin and core minus skin between the two groups of patients were not statistically significant. There was no correlation between temperature and the level of coma or parasitaemia for cerebral and uncomplicated malaria patients. There was a positive correlation between brain and core temperature in both groups of patients during the febrile phase. Brain temperature remained lower than core temperature in cerebral and uncomplicated malaria as in normal children. Normal thermoregulation appears to be maintained in cerebral malaria.

  • 7.
    Klein, Marcus
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    A comparison of specific heat ratio models for cylinder pressure modeling2004Conference paper (Refereed)
  • 8.
    Ullbrand, Jennifer
    Linköping University, Department of Physics, Chemistry and Biology.
    A comparison of SPS  and HP sintered, electroless copper plated carbon nanofibre composites for heat sink applications2009Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to synthesize a material with high thermal conductivity and a low coefficient of thermal expansion (CTE), useful as a heat sink. Carbon nanofibres (CNF) are first coated with copper by an electroless plating technique and then sintered to a solid sample by either spark plasma sintering (SPS) or hot pressing (HP). The final product is a carbon nanofibre reinforced copper composite. Two different fibre structures are considered: platlet (PL) and herringbone (HB). The influence of the amount of CNF reinforcement (6-24 %wt), on the thermal conductivity and CTE is studied. CNF has an excellent thermal conductivity in the direction along the fibre while it is poor in the transverse direction. The CTE is close to zero in the temperature range of interest. The adhesion of Cu to the CNF surface is in general poor and thus improving the the wetting of the copper by surface modifications of the fibres are of interest such that thermal gaps in the microstructure can be avoided. The poor wetting results in CNF agglomerates, resulting in an inhomogeneous microstructure. In this report a combination of three different types of surface modifications has been tested: (1) electroless deposition of copper was used to improve Cu impregnation of CNF; (2) heat treatment of CNF to improve wetting; and (3) introduction of a Cr buffer layer to further enhance wetting. The obtained composite microstructures are characterized in terms of chemical composition, grain size and degree of agglomeration. In addition their densities are also reported. The thermal properties were evaluated in terms of thermal diffusivity, thermal conductivity and CTE. Cr/Cu coated platelet fibres (6wt% of CNF reinforcement) sintered by SPS is the sample with the highest thermal conductivity, ~200 W/Km. The thermal conductivity is found to decrease with increasing content of CNFs.

  • 9.
    Berntsson, Fredrik
    et al.
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Eldén, Lars
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Garcia-Padrón, Ricardo
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    A Comparison of Three Numerical Methods for an Inverse Heat Conduction Problem and an Industrial Application1997Conference paper (Other academic)
  • 10.
    Bengtsson, Mikael
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A Control-Oriented 0D Model of a Turbocharger Gas Stand Including Heat Transfer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A turbocharger’s performance is measured in a gas stand in order to provide information of the components characteristics. The measurement procedure is a very time consuming process and it is thus desired to make it more time-efficient.

    To allow for development of an enhanced control strategy used during the measurements, a 0D model of a gas stand is developed. The physical gas stand components are modeled and validated against measurements, all showing a reasonable result. Turbocharger heat transfers are investigated and modeled using a lumped capacitance approach. The heat transfer models shows approximative results when comparing with measurements which is explained by the lack of temperature measurement made on the bearing housing.

    When the complete gas stand model is validated against measurements, an improvement of the measurement procedure is examined. By adding an idealized heat source with the possibility to heat the compressor housing, it is possible to reduce the time it takes to reach an equilibrium when switching between two steady state operating points. 

  • 11.
    Berntsson, Fredrik
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Mpinganzima, Lydie
    National University of Rwanda, Box 117, Butare, Rwanda.
    A Data Assimilation Approach to Coefficient Identification2011Report (Other academic)
    Abstract [en]

    The thermal conductivity properties of a material can be determined experimentally by using temperature measurements taken at specified locations inside the material. We examine a situation where the properties of a (previously known) material changed locally. Mathematically we aim to find the coefficient k(x) in the stationary heat equation (kTx)x = 0;under the assumption that the function k(x) can be parametrized using only a few degrees of freedom.

    The coefficient identification problem is solved using a least squares approach; where the (non-linear) control functional is weighted according to the distribution of the measurement locations. Though we only discuss the 1D case the ideas extend naturally to 2D or 3D. Experimentsdemonstrate that the proposed method works well.

     

     

     

     

  • 12. Gracia-Padron, Ricardo
    et al.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    A Drying Process of Lacquer Coating in Wood Manufacturing Industry - Simulations and Experiments1999In: The Third Baltic Heat Transfer Conference,1999, 1999, 659-666 p.Conference paper (Refereed)
  • 13.
    Wiker, Niclas
    et al.
    Linköping University, Department of Management and Engineering, Mechanics . Linköping University, The Institute of Technology.
    Klarbring, Anders
    Linköping University, Department of Management and Engineering, Mechanics . Linköping University, The Institute of Technology.
    A General Multiphysic Model for Planar (2D) Flow Problems2008Report (Other academic)
    Abstract [en]

    A general 2D model for fluid flow mixed with heat/mass transfer is developed.The aim is to derive a framework of planar state equations that includes someboundary effects in the out–of–plane dimension to be used in multiphysicproblems. The use of the framework is demonstrated by deriving a slightextension to an existing model for mixed fluid/heat flow.

  • 14.
    Neely, G Gregory
    et al.
    Austrian Academy of Science.
    Hess, Andreas
    University of Erlangen Nurnberg.
    Costigan, Michael
    Harvard University.
    Keene, Alex C
    NYU.
    Goulas, Spyros
    Austrian Academy of Science.
    Langeslag, Michiel
    Innsbruck Medical University.
    Griffin, Robert S
    Massachusetts General Hospital.
    Belfer, Inna
    University of Pittsburgh.
    Dai, Feng
    University of Pittsburgh.
    Smith, Shad B
    University N Carolina.
    Diatchenko, Luda
    University N Carolina.
    Gupta, Vaijayanti
    Strand Life Science Pvt Ltd.
    Xia, Cui-Ping
    Austrian Academy Science.
    Amann, Sabina
    Austrian Academy of Science.
    Kreitz, Silke
    University of Erlangen Nurnberg.
    Heindl-Erdmann, Cornelia
    University of Erlangen Nurnberg.
    Wolz, Susanne
    University of Erlangen Nurnberg.
    Ly, Cindy V
    Strand Life Science Pvt Ltd.
    Sarangi, Rinku
    Strand Life Science Pvt Ltd.
    Dan, Debasis
    Strand Life Science Pvt Ltd.
    Novatchkova, Maria
    Austrian Academy of Science.
    Rosenzweig, Mark
    Brandeis University.
    Gibson, Dustin G
    University N Carolina.
    Truong, Darwin
    Austrian Academy of Science.
    Schramek, Daniel
    Austrian Academy of Science.
    Zoranovic, Tamara
    Austrian Academy of Science.
    Cronin, Shane J F
    Austrian Academy of Science.
    Angjeli, Belinda
    Austrian Academy of Science.
    Brune, Kay
    University of Erlangen Nurnberg.
    Dietzl, Georg
    Stanford University.
    Maixner, William
    University N Carolina.
    Meixner, Arabella
    Austrian Academy of Science.
    Thomas, Winston
    Deltagen Inc.
    Pospisilik, J Andrew
    Max Planck Institute.
    Alenius, Mattias
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology, IKE.
    Kress, Michaela
    Innsbruck Medical University.
    Subramaniam, Sai
    Strand Life Science Pvt Ltd.
    Garrity, Paul A
    Brandeis University.
    Bellen, Hugo J
    Baylor College of Medicine.
    Woolf, Clifford J
    Harvard University.
    Penninger, Josef M
    Austrian Academy of Science.
    A Genome-wide Drosophila Screen for Heat Nociception Identifies alpha 2 delta 3 as an Evolutionarily Conserved Pain Gene2010In: CELL, ISSN 0092-8674, Vol. 143, no 4, 628-638 p.Article in journal (Refereed)
    Abstract [en]

    Worldwide, acute, and chronic pain affects 20% of the adult population and represents an enormous financial and emotional burden. Using genome-wide neuronal-specific RNAi knockdown in Drosophila, we report a global screen for an innate behavior and identify hundreds of genes implicated in heat nociception, including the alpha 2 delta family calcium channel subunit straightjacket (stj). Mice mutant for the stj ortholog CACNA2D3 (alpha 2 delta 3) also exhibit impaired behavioral heat pain sensitivity. In addition, in humans, alpha 2 delta 3 SNP variants associate with reduced sensitivity to acute noxious heat and chronic back pain. Functional imaging in alpha 2 delta 3 mutant mice revealed impaired transmission of thermal pain-evoked signals from the thalamus to higher-order pain centers. Intriguingly, in alpha 2 delta 3 mutant mice, thermal pain and tactile stimulation triggered strong cross-activation, or synesthesia, of brain regions involved in vision, olfaction, and hearing.

  • 15.
    Spyrou, Giannis
    et al.
    Department of Biosciences at Novum, Center for Biotechnology, Karolinska Institute, Huddinge, Sweden.
    Wilson, William
    Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden.
    Padilla, Alicia C.
    University of Córdoba, Spain.
    Holmgren, Arne
    Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
    Miranda-Vizuete, Antonio
    Department of Biosciences at Novum, Center for Biotechnology, Karolinska Institute, Huddinge, Sweden.
    A genome-wide survey of human thioredoxin and glutaredoxin family pseudogenes2001In: Human Genetics, ISSN 0340-6717, E-ISSN 1432-1203, Vol. 109, no 4, 429-439 p.Article in journal (Refereed)
    Abstract [en]

    The thioredoxin/glutaredoxin family consists of small heat-stable proteins that have a highly conserved CXXC active site and that participate in the regulation of many redox reactions. We have searched the human genome sequence to find putative pseudogenes (non-functional copies of protein-coding genes) for all known members of this family. This survey has resulted in the identification of seven processed pseudogenes for human Trx1 and two more for human Grx1. No evidence for the presence of processed pseudogenes has been found for the remaining members of this family. In addition, we have been unable to detect any non-processed pseudogenes derived from any member of the family in the human genome. The seven thioredoxin pseudogenes can be divided into two groups: Trx1-psi2, -psi3, -psi4, -psi5 and -psi6 arose from the functional ancestor, whereas Trx1-psi1 and -psi7 originated from Trx1-psi2 and -psi6, respectively. In all cases, the pseudogenes originated after the human/rodent radiation as shown by phylogenetic analysis. This is also the case for Grx1-psi1 and Grx1-psi2, which are placed between rodent and human sequences in the phylogenetic tree. Our study provides a molecular record of the recent evolution of these two genes in the hominid lineage.

  • 16.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Sjödin, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Erlandsson, B-E
    A Heat Transfer Analysis of Microwave Thermal Therapy of the Prostate2000In: Annual International Conference of the IEEE Engineering in Medicine biology Society,2000, 2000Conference paper (Other academic)
  • 17.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Karlsson, Matts
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Modelling and Simulation .
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    A hybrid equation for simulation of perfused tissue during thermal treatment2001In: International Journal of Hyperthermia, ISSN 0265-6736, Vol. 17, no 6, 483-498 p.Article in journal (Refereed)
    Abstract [en]

    Bio-heat equations (BHEs) are necessary for predicting tissue temperature during thermal treatment. For some applications, however, existing BHEs describe the convective heat transfer by the blood perfusion in an unsatisfactory way. The two most frequently used equations, the BHE of Pennes and the keff equation, use for instance either a heat sink or an increased thermal conductivity in order to account for the blood perfusion. Both these methods introduce modelling inaccuracies when applied to an ordinary tissue continuum with a variety of vessel sizes. In this study, a hybrid equation that includes both an increased thermal conductivity and a heat sink is proposed. The equation relies on the different thermal characteristics associated with small, intermediate and large sized vessels together with the possibilities of modelling these vessels using an effective thermal conductivity in combination with a heat sink. The relative importance of these two terms is accounted for by a coefficient ▀. For ▀ = 0 and ▀ = 1, the hybrid equation coincides with the BHE of Pennes and the keff equation, respectively. The hybrid equation is used here in order to simulate temperature fields for two tissue models. The temperature field is greatly affected by ▀, and the effect is dependent on, e.g. the boundary conditions and the power supply. Since the BHE of Pennes and the keff equation are included in the hybrid equation, this equation can also be useful for evaluation of the included equations. Both these heat transfer modes are included in the proposed equation, which enables implementation in standard thermal simulation programmes.

  • 18.
    Sahlberg, Jörgen
    Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
    A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling1983In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 14, no 4, 239-254 p.Article in journal (Refereed)
    Abstract [en]

    A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

  • 19.
    Johansson, Tomas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lesnic, Daniel
    University of Leeds, England .
    Reeve, Thomas
    University of Birmingham, England .
    A Mesh less Regularization Method for a Two-Dimensional Two-Phase Linear Inverse Stefan Problem2014In: Advances in Applied Mathematics and Mechanics, ISSN 2070-0733, Vol. 5, no 6, 825-845 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, a meshless regularization method of fundamental solutions is proposed for a two-dimensional, two-phase linear inverse Stefan problem. The numerical implementation and analysis are challenging since one needs to handle composite materials in higher dimensions. Furthermore, the inverse Stefan problem is ill-posed since small errors in the input data cause large errors in the desired output solution. Therefore, regularization is necessary in order to obtain a stable solution. Numerical results for several benchmark test examples are presented and discussed.

  • 20.
    Johansson, Tomas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lesnic, Daniel
    University of Leeds, England .
    Reeve, Thomas
    University of Birmingham, England .
    A meshless method for an inverse two-phase one-dimensional nonlinear Stefan problem2014In: Mathematics and Computers in Simulation, ISSN 0378-4754, Vol. 101, 61-77 p.Article in journal (Refereed)
    Abstract [en]

    We extend a meshless method of fundamental solutions recently proposed by the authors for the one-dimensional two-phase inverse linear Stefan problem, to the nonlinear case. In this latter situation the free surface is also considered unknown which is more realistic from the practical point of view. Building on the earlier work, the solution is approximated in each phase by a linear combination of fundamental solutions to the heat equation. The implementation and analysis are more complicated in the present situation since one needs to deal with a nonlinear minimization problem to identify the free surface. Furthermore, the inverse problem is ill-posed since small errors in the input measured data can cause large deviations in the desired solution. Therefore, regularization needs to be incorporated in the objective function which is minimized in order to obtain a stable solution. Numerical results are presented and discussed.

  • 21.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Persson, Peter
    IKP .
    A method for determination of intra-valve heat transfer in thermostatic mixing valves2006In: International Conference on Heat and Mass Transfer,2006, Miami, Florida, USA: WSEAS/IASME , 2006, 46- p.Conference paper (Refereed)
    Abstract [en]

      

  • 22.
    Ewest, D.
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering. Siemens Ind Turbomachinery AB, Sweden.
    Almroth, P.
    Siemens Ind Turbomachinery AB, Sweden.
    Sjodin, B.
    Siemens Ind Turbomachinery AB, Sweden.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Leidermark, Daniel
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    A modified compliance method for fatigue crack propagation applied on a single edge notch specimen2016In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 92, 61-70 p.Article in journal (Refereed)
    Abstract [en]

    Crack length measurements with high accuracy are often difficult to achieve during fatigue crack propagation testing under non-isothermal conditions. In this work a modified approach to the compliance method defined in e.g. ASTM E647 is described, which is better suited for high loads, varying temperatures and for taking the scatter in Youngs modulus into account. A numerical finite element study is performed for a single edge notch specimen, to investigate the influence of initiation locations on the accuracy of the method. The change in cracked area versus change in stiffness for three different cases are numerically shown to collapse to one curve, i.e. the result is not significantly affected by how the crack is initiated. The numerical study is compared to results from two experiments using different materials, with heat tinting during the tests for extracting snapshots of the crack fronts. A good agreement between the experiments and the numerical study is shown. A new compliance curve and a new geometry function for the stress intensity factor is proposed for the single edge notch specimen. (C) 2016 Elsevier Ltd. All rights reserved.

  • 23.
    Nadali Najafabadi, Hossein
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Utriainen, Esa
    Kinell, Mats
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    A Modified Correlation for Film Effectiveness Prediction of Cylindrical Holes at the Suction Side of A turbine Guide Vane2011In: Proceedings of the 6th Baltic Heat Transfer Conference, Tampere Convention Bureau , 2011Conference paper (Other academic)
  • 24.
    Lee, In-Seon
    et al.
    Kyung Hee University, South Korea; University of Tubingen, Germany; University of Tubingen, Germany; University of Tubingen, Germany.
    Lee, Bombi
    Kyung Hee University, South Korea.
    Park, Hi-Joon
    Kyung Hee University, South Korea.
    Olausson, Håkan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Clinical Neurophysiology.
    Enck, Paul
    University of Tubingen, Germany.
    Chae, Younbyoung
    Kyung Hee University, South Korea.
    A new animal model of placebo analgesia: involvement of the dopaminergic system in reward learning2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, no 17140Article in journal (Refereed)
    Abstract [en]

    We suggest a new placebo analgesia animal model and investigated the role of the dopamine and opioid systems in placebo analgesia. Before and after the conditioning, we conducted a conditioned place preference (CPP) test to measure preferences for the cues (Rooms 1 and 2), and a hot plate test (HPT) to measure the pain responses to high level-pain after the cues. In addition, we quantified the expression of tyrosine hydroxylase (TH) in the ventral tegmental area (VTA) and c-Fos in the anterior cingulate cortex (ACC) as a response to reward learning and pain response. We found an enhanced preference for the low level-pain paired cue and enhanced TH expression in the VTA of the Placebo and Placebo + Naloxone groups. Haloperidol, a dopamine antagonist, blocked these effects in the Placebo + Haloperidol group. An increased pain threshold to high-heat pain and reduced c-Fos expression in the ACC were observed in the Placebo group only. Haloperidol blocked the place preference effect, and naloxone and haloperidol blocked the placebo analgesia. Cue preference is mediated by reward learning via the dopamine system, whereas the expression of placebo analgesia is mediated by the dopamine and opioid systems.

  • 25.
    Nielsen, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Sandberg, Tony
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A New Model for Rolling Resistance of Pneumatic Tires2003In: SAE Technical Papers, ISSN 0148-7191, Vol. 111, no 6, 1572-1579 p.Article in journal (Refereed)
    Abstract [en]

    Rolling resistance of inflated tires is a factor that contributes to the total load and fuel consumption of a vehicle. Therefore, models of rolling resistance is an important area within computer simulations of vehicles used to predict fuel consumption and emissions. In these applications the coefficient of rolling resistance is usually described as a function of velocity. We have earlier shown that this is not a satisfactory solution [1, 2].

    In this paper it is demonstrated that the temperature of the tires is a dominating factor for rolling resistance in real driving. The tires typically start at ambient temperature and are then warmed up by the heat generated in the tire. As the temperature increases the rolling resistance decreases (to some limit). After a long period (2 hours for truck tires) of driving at constant conditions, a stationary temperature (and rolling resistance) is reached. In real driving there are usually also other (faster) changes in conditions, like a speed change, that affects the rolling resistance as described in the traditional velocity models.

    These aspects are demonstrated and lead to a proposal of a new model for rolling resistance. The new model is based on the relation between rolling resistance and tire temperature at stationarity. A differential equation for the tire temperature uses the relation between momentary temperature and stationary temperature as input. A speed dependent term is used to model fast changes of speed. In this way both fast and slow phenomena can be described.

    The new model is in good agreement with results published by others. Further, in our own experiments with a heavy truck the new model has shown a very good ability to calculate the true dynamic rolling resistance.

  • 26.
    Rahm, Lars
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    A note on the heat-up of an initially isotherm fluid1985In: Mathematical Modelling, ISSN 0270-0255, Vol. 6, 19-30 p.Article in journal (Refereed)
  • 27.
    Ranjbar, Zohreh
    et al.
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Eldén, Lars
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    A Preconditioned GMRES Method for Solving a 1D Sideways Heat  Equation2010Report (Other academic)
    Abstract [en]

    The sideways Heat equation (SHE) is a model of the problem of determining the temperature on the surface of a body from the interior measurements. Mathematically it can be formulated as a non-characteristic Cauchy problem for a  parabolic partial differential equation. This problem is severely ill-posed: the solution does not depend continuously on the data. We use a preconditioned Generalized Minimum Residuals Method (GMRES) to solve a 1D SHE. Regularization is used in the preconditioner as well as truncating the GMRES algorithm. Numerical experiments demonstrate that the proposed method works well.

  • 28.
    Chapko, Roman
    et al.
    Ivan Franko National University of Lviv, Ukraine .
    Johansson, Tomas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Nephrology.
    Vavrychuk, Vasyl
    Ivan Franko National University of Lviv, Ukraine .
    A projected iterative method based on integral equations for inverse heat conduction in domains with a cut2013In: Inverse Problems, ISSN 0266-5611, E-ISSN 1361-6420, Vol. 29, no 6, 065003- p.Article in journal (Refereed)
    Abstract [en]

    The Cauchy problem for the parabolic heat equation, consisting of the reconstruction of the solution from knowledge of the temperature and heat flux on a part of the boundary of the solution domain, is investigated in a planar region containing a cut. This linear inverse ill-posed problem is numerically solved using an iterative regularization procedure, where at each iteration step mixed Dirichlet-Neumann problems for the parabolic heat equation are used. Using the method of Rothe these mixed problems are reduced to a sequence of boundary integral equations. The integral equations have a square root singularity in the densities and logarithmic and hypersingularities in the kernels. Moreover, the mixed parabolic problems have singularities near the endpoints of the cut. Special techniques are employed to handle each of these (four) types of singularities, and analysis is performed in weighted spaces of square integrable functions. Numerical examples are included showing that the proposed regularizing procedure gives stable and accurate approximations.

  • 29.
    Klugman, Sofia
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    A Scandinavian chemical wood-pulp mill. Part 1. Energy audit aiming at efficiency measures2007In: Applied Energy, ISSN 0306-2619, Vol. 84, no 3, 326-339 p.Article in journal (Refereed)
    Abstract [en]

    A Swedish wood-pulp mill is surveyed in terms of energy supply and use in order to determine the energy-saving potential. Conservation measures are of increasing interest to Swedish industry, as energy prices have continued to rise in recent years. The electricity price particularly increased after the deregulation of the Scandinavian electricity market in 1996. The deregulation expanded to all of the EU in July 2004, which may increase the Swedish electricity price further until it reaches the generally higher European price level. Furthermore, oil prices have increased and the emissions trading scheme for CO2 adds to the incentive to reduce oil consumption. The energy system at the surveyed pulp mill is described in terms of electricity and process heat production and use. The total energy-saving potential is estimated and some saving points are identified. The heat that today is wasted at the mill has been surveyed in order to find potential for heat integration or heat export. The result shows that the mill probably could become self-sufficient in electricity. Particularly important in that endeavour is updating old pumps.

  • 30.
    Klugman, Sofia
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    A Scandinavian chemical wood-pulp mill. Part 2. International and model mills comparison.2007In: Applied Energy, ISSN 0306-2619, Vol. 84, no 3, 340-350 p.Article in journal (Refereed)
    Abstract [en]

    The energy use at a Swedish chemical wood-pulp mill is compared internationally and for two model mills that aim to use the most efficient available technology. The international comparison is performed between Canadian and Scandinavian pulp-mills on a general level, and on a closer level among eleven Swedish and Finnish non-integrated sulfate pulp-mills, the type of mill considered in the case study. The two model mills that are used for comparison are one Swedish and one Canadian. The Scandinavian pulp-mills are somewhat more energy efficient than the Canadian mills. Still, the variation in energy use is remarkably large among the Scandinavian mills, which indicates that the energy-saving potential is great. If all Swedish freestanding sulfate pulp-mills became as energy efficient as the most efficient Scandinavian mill, electricity savings corresponding to nearly 1% of the national electricity use would be obtained. In the model mills comparison it was found that large amounts of heat could be saved, particularly in the evaporation plant.

  • 31.
    Ranjbar, Zohreh
    et al.
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Eldén, Lars
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    A Sideways Heat Equation Applied to the Measurement of the Gas Temperature in a Combustion Chamber2010Report (Other academic)
    Abstract [en]

    We consider a Cauchy problem for a parabolic equation as a mathematical model of the temperature development inside a suction pyrometer. Such devices are often used to calibrate the temperature sensor in a combustion chamber. Mathematically the problem is severely ill-posed and needs to be regularized. The model is simplified to make it one-dimensional in space. The temperature measurements are done in two steps. First, the heat transfer coefficient is approximated via a calibration experiment. Then the gas temperature in the combustion chamber is computed using a convection boundary condition. In both steps one computes the surface temperature and heat flux based on interior measurements in the thermocouple. Numerical examples are presented to test the proposed approach.

  • 32.
    Paulsson, Dan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Gustavsson, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    A Soft Sensor for Bioprocess Control Based on Sequential Filtering of Metabolic Heat Signals2014In: Sensors, ISSN 1424-8220, Vol. 14, no 10, 17864-17882 p.Article in journal (Refereed)
    Abstract [en]

    Soft sensors are the combination of robust on-line sensor signals with mathematical models for deriving additional process information. Here, we apply this principle to a microbial recombinant protein production process in a bioreactor by exploiting bio-calorimetric methodology. Temperature sensor signals from the cooling system of the bioreactor were used for estimating the metabolic heat of the microbial culture and from that the specific growth rate and active biomass concentration were derived. By applying sequential digital signal filtering, the soft sensor was made more robust for industrial practice with cultures generating low metabolic heat in environments with high noise level. The estimated specific growth rate signal obtained from the three stage sequential filter allowed controlled feeding of substrate during the fed-batch phase of the production process. The biomass and growth rate estimates from the soft sensor were also compared with an alternative sensor probe and a capacitance on-line sensor, for the same variables. The comparison showed similar or better sensitivity and lower variability for the metabolic heat soft sensor suggesting that using permanent temperature sensors of a bioreactor is a realistic and inexpensive alternative for monitoring and control. However, both alternatives are easy to implement in a soft sensor, alone or in parallel.

  • 33.
    Klein, Marcus
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    A specific heat ratio model and compression ratio estimation2004Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Cylinder pressure modeling and heat release analysis are today important and standard tools for engineers and researchers, when developing and tuning new engines. An accurate specific heat ratio model is important for an accurate heat release analysis, since the specific heat ratio couples the systems energy to other thermodynamic quantities.

    The objective of the first part is therefore to investigate models of the specific heat ratio for the single-zone heat release model, and find a model accurate enough to introduce a cylinder pressure modeling error less than or in the order of the cylinder pressure measurement noise, while keeping the computational complexity at a minimum. As reference, a specific heat ratio is calculated for burned and unburned gases, assuming that the unburned mixture is frozen and that the burned is at chemical equilibrium. Use of the reference model in heat release analysis is too time consuming and therefore a set of simpler models. both existing and newly developed, are compared to the reference model.

    A two-zone mean temperature model and the Vibe function are used to parameterize the mass fraction burned. The mass fraction burned is used to interpolate the specific heats for the unburned and burned mixture, and then form the specific heat ratio, which renders a small enough modeling error in γ. The impact that t his modeling error has on the cylinder pressure is less than that of the measurement noise, and fifteen times smaller than the model originally suggested in Gatowski et al. [1984]. The computational time is increased with 40 % compared to the original setting, but reduced by a factor 70 compared to precomputed tables from the full equilibrium program. The specific heats for the unburned mixture are captured within 0.2 % by linear functions, and the specific heats for the burned mixture are captured within 1 % by higher-order polynomials for the major operating range of a spark ignited (SI) engine.

    The second part is on compression ratio estimation based on measured cylinder pressure traces. Four methods for compression ratio estimation based on both motored and fired cylinder pressure traces are described and evaluated for simulated and experimental data. The first three methods rely upon a model of polytropic compression for the cylinder pressure, and it is shown that they give a good estimate of the compression ratio for simulated cycles at low compression ratios, although the estimat es are biased. The polytropic model lacks information about heat transfer and therefore, for high compression ratios, this model error causes the estimates to become more biased. The fourth method includes heat transfer, crevice effects, and a commonly used heat release model for firing cycles. This method is able to estimate the compression ratio more accurately at both low and high compression ratios. An investigation of how the methods perform when subjected to parameter deviations in crank angle phasing, cylinder pressure bias and heat transfer shows that the third and fourth method can deal with these parameter deviations.

  • 34.
    Klein, Markus
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    A specific heat ratio model for single-zone heat release models2004In: SAE Technical Papers 2004-01-1464, SAE International , 2004, 2004-01-1464Conference paper (Refereed)
    Abstract [en]

    The objective is to investigate models of the specific heat ratio for the single-zone heat release model, and find a model accurate enough to introduce a modeling error less than or in the order of the cylinder pressure measurement noise, while keeping the computational complexity at a minimum. Based on assumptions of frozen mixture for the unburned mixture and chemical equilibrium for the burned mixture, the specific heat ratio is calculated using a full equilibrium program for an unburned and a burned air-fuel mixture, and compared to already existing and newly proposed approximative models of γ.

    A two-zone mean temperature model, Matekunas pressure ratio management and the Vibe function are used to parameterize the mass fraction burned. The mass fraction burned is used to interpolate the specific heats for the unburned and burned mixture, and then form the specific heat ratio, which renders a small enough modeling error in γ. The specific heats for the unburned mixture is captured within 0.2 % by a linear function, and the specific heats for the burned mixture is captured within 1 % by a higher-order polynomial for the major operating range of a spark ignited (SI) engine.

  • 35.
    Berntsson, Fredrik
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    A spectral method for solving the sideways heat equation1999In: Inverse Problems, ISSN 0266-5611, E-ISSN 1361-6420, Vol. 15, no 4, 891-906 p.Article in journal (Refereed)
    Abstract [en]

    We consider an inverse heat conduction problem, the sideways heat equation, which is the model of a problem where one wants to determine the temperature on the surface of a body, using interior measurements. Mathematically it can be formulated as a Cauchy problem for the heat equation, where the data are given along the line x = 1, and a solution is sought in the interval 0 ≤ x < 1.

    The problem is ill-posed, in the sense that the solution does not depend continuously on the data. Continuous dependence of the data is restored by replacing the time derivative in the heat equation with a bounded spectral-based approximation. The cut-off level in the spectral approximation acts as a regularization parameter. Error estimates for the regularized solution are derived and a procedure for selecting an appropriate regularization parameter is given. The discretized problem is an initial value problem for an ordinary differential equation in the space variable, which can be solved using standard numerical methods, for example a Runge-Kutta method. As test problems we take equations with constant and variable coefficients.

  • 36.
    Elden, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Scientific Computing.
    Berntsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Scientific Computing.
    A stability estimate for a Cauchy problem for an elliptic partial differential equation2005In: Inverse Problems, ISSN 0266-5611, Vol. 21, no 5, 1643-1653 p.Article in journal (Refereed)
    Abstract [en]

    A two-dimensional inverse steady state heat conduction problem in the unit square is considered. Cauchy data are given for y ≤ 0, and boundary data are for x ≤ 0 and x ≤ 1. The elliptic operator is self-adjoint with non-constant, smooth coefficients. The solution for y ≤ 1 is sought. This Cauchy problem is ill-posed in an L2-setting. A stability functional is defined, for which a differential inequality is derived. Using this inequality a stability result of Hölder type is proved. It is demonstrated explicitly how the stability depends on the smoothness of the coefficients. The results can also be used for rectangle-like regions that can be mapped conformally onto a rectangle. © 2005 IOP Publishing Ltd.

  • 37.
    Lindström, Jens
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    A stable and high order accurate conjugate heat transfer problem2009Report (Other academic)
    Abstract [en]

    This paper analyzes well-posedness and stability of a conjugate heat transfer problem in one space dimension. We study a model problem for heat transfer between a fluid and a solid. The energy method is used to derive boundary and interface conditions that make the continuous problem well-posed and the semi-discrete problem stable. The numerical scheme is implemented using 2nd, 3rd and 4th order finite difference operators on Summation-By-Parts (SBP) form. The boundary and interface conditions are implemented weakly. We investigate the spectrum of the spatial discretization to determine which type of coupling that gives attractive convergence properties. The rate of convergence is verified using the method of manufactured solutions.

  • 38.
    Lindström, Jens
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    A stable and high order interface procedure for conjugate heat transfer problems2010In: Numerical Mathematics and Advanced Applications: 2009, Berlin: Springer-Verlag , 2010, 599-607 p.Conference paper (Refereed)
  • 39.
    Lindström, Jens
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    A stable and high-order accurate conjugate heat transfer problem2010In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 229, no 14, 5440-5456 p.Article in journal (Refereed)
    Abstract [en]

    This paper analyzes well-posedness and stability of a conjugate heat transfer problem in one space dimension. We study a model problem for heat transfer between a fluid and a solid. The energy method is used to derive boundary and interface conditions that make the continuous problem well-posed and the semi-discrete problem stable. The numerical scheme is implemented using 2nd-, 3rd- and 4th-order finite difference operators on Summation-By-Parts (SBP) form. The boundary and interface conditions are implemented weakly. We investigate the spectrum of the spatial discretization to determine which type of coupling that gives attractive convergence properties. The rate of convergence is verified using the method of manufactured solutions.

  • 40.
    Feldmann, Andreas
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    A Strategic Perspective on Plants in Manufacturing Networks2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation addresses the topic of manufacturing network strategies, with a particular focus on the plant perspective. Research on manufacturing networks aims at contributing decision support on how to set up and how to coordinate factories that act in a global setting. Manufacturing networks are networks consisting of wholly owned plant, as opposed to supply chains management where also plants belonging to other organisations are considered. Research on the role of the plant in manufacturing networks can help to gain insights in how the network works and how to achieve network-related competitive advantages. Over the last two decades there has been a trend in increased globalisation and when companies expand beyond their home markets there is a leap in complexity that needs to be handled. A survey of Swedish plants shows that a large majority of medium and large sized plants are part in some kind of manufacturing network, making research on such networks highly relevant.

    The overall objective of this dissertation is to investigate how factories fit into the network in terms of roles, strategic autonomy and market configurations. Much research has either focused on networks as a whole, often assuming similar or identical plants, or the focus has been on plant internal decision. This research addresses the borderland between plant and network. This dissertation addresses two research objectives. The first is to investigate the relationship between networks and plants roles with particular focus on Swedish based networks and plants and the second is to test and further develop the theory on plant roles.

    The empirical data that was used in the dissertation was the product of a mail survey and a case study at a manufacturer of heat exchangers. The survey was sent to 563 Swedish factories and included information on competitive priorities, processes, plant roles, performance, suppliers, risk as well as general product and company information. Using focus groups, the case company was followed from the start of the project in January 2006. Following the case company during five years gave the opportunity to study networks in transformation.

    The research contributed to several insights to the area of plant roles and manufacturing networks as well as to practitioners in manufacturing. Internal and external suppliers are handled differently in terms of selection criteria, which indicates different roles in the network. Detailed exploration of individual site competences has lead to an improved model based on competence themes and links between the plant level and the network level have been established. Additionally we contribute to the manufacturing strategy process area by investigating and suggesting a model for strategic decision autonomy in manufacturing networks. The results are aimed at providing guidance for decision making in manufacturing networks as well as providing an improved foundation for further research in the area.

    List of papers
    1. Designing and managing manufacturing networks: a survey of Swedish plants
    Open this publication in new window or tab >>Designing and managing manufacturing networks: a survey of Swedish plants
    2009 (English)In: Production planning & control (Print), ISSN 0953-7287, E-ISSN 1366-5871, Vol. 20, no 2, 101-112 p.Article in journal (Refereed) Published
    Abstract [en]

    The design and management of the manufacturing network for a firm is an important factor for its competitive position. By manufacturing network we mean the plant or plants of a manufacturing firm and the relationships with external suppliers. The way that these operate together is crucial for supporting the competition of the products in the marketplace. This article presents the results of a survey of 106 Swedish manufacturing plants. We find that the markets and supply networks of Swedish plants are global, but there is a focus on Europe. The main reason for locating a plant in Sweden is proximity to skills and knowledge, and we find no pure low-cost plants. The overall level of site competence is very high. There are many significant differences between how internal and external suppliers are selected. The choice of internal suppliers, i.e. those suppliers in the manufacturing network that belong to the same firm, is to a large extent based on a single corporate decision reflecting quality and competence, while external suppliers are chosen based on quality, price and delivery dependability considerations. This study provides a broad analysis of the manufacturing networks in which Swedish plants operate, and the roles of these plants.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2009
    Keyword
    empirical analysis, operations management, supply chain management, survey research, Sweden
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-17137 (URN)10.1080/09537280802705252 (DOI)000263561600002 ()
    Note

    This is an electronic version of an article published in:Andreas Feldmann, Jan Olhager and Fredrik Persson, Designing and managing manufacturing networks-a survey of Swedish plants, 2009, PRODUCTION PLANNING and CONTROL, (20), 2, 101-112.PRODUCTION PLANNING and CONTROL is available online at informaworldTM: http://dx.doi.org/10.1080/09537280802705252Copyright: Taylor & Francishttp://www.tandf.co.uk/journals/default.asp

    Available from: 2009-03-23 Created: 2009-03-07 Last updated: 2014-03-18Bibliographically approved
    2. Internal and external suppliers in manufacturing networks: An empirical analysis
    Open this publication in new window or tab >>Internal and external suppliers in manufacturing networks: An empirical analysis
    2008 (English)In: Operations Management Research, ISSN 1936-9735, E-ISSN 1936-9743, Vol. 1, no 2, 141-149 p.Article in journal (Refereed) Published
    Abstract [en]

    The purpose of the paper is to explore the way manufacturing firms use internal and external suppliers in the design and management of manufacturing networks. The main area of interest is to explore the similarities and differences between internal and external suppliers, with respect to their roles and the reasons for choosing a certain type of supplier. We base our analysis on data from 104 Swedish manufacturing plants and their corresponding manufacturing networks of internal and external suppliers. The results of the study show that there are significant differences between the criteria that are influential in choosing a certain type of supplier. The choice of an internal supplier is largely based on a single corporate decision, while an external supplier has to perform well on a number of criteria (primarily quality, cost, and delivery dependability). When comparing the selection criteria with competitive priorities and plant performance, we find that the criteria for selecting external suppliers has a better match than those for selecting internal suppliers. The sample contained plants having only external suppliers as well as plants having both internal and external suppliers, but the selection criteria for external suppliers are the same for both groups and not dependent upon the presence or absence of internal suppliers.

    Place, publisher, year, edition, pages
    Springer-Verlag New York, 2008
    Keyword
    Make-or-buy, Strategic sourcing, Supplier selection
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-19437 (URN)10.1007/s12063-008-0011-1 (DOI)
    Projects
    PROFIL (Vinnova)
    Available from: 2009-06-26 Created: 2009-06-23 Last updated: 2017-01-19Bibliographically approved
    3. Bundles of site competences in defining plant roles
    Open this publication in new window or tab >>Bundles of site competences in defining plant roles
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Purpose: To investigate the strategic role of plants, in terms of the type and level of sitecompetence, the relationship with the strategic reason for location, and the impact onoperational performance.

    Design/methodology: We use a survey of 103 Swedish manufacturing plants that belong to international manufacturing networks. We analyze patterns within this context to identify potential archetypes of plants with respect to plant roles, based on factor analysis and cluster analysis.

    Findings: We find that the areas of site competence can be grouped into three bundles, characterized thematically as production-related, supply chain-related and developmentrelated. The plants fall into three categories: some plants have only production-related competences, some have competences concerning both production and supply chain, and the third group of plants possesses all three bundles of competences.

    Research limitations/implications: The results provide empirical evidence that site competences come in bundles in three steps according to themes rather than individually. We find no significant relationship between the level of site competence and the strategic reason for site location.

    Practical implications: The results provide insights into how site competence areas are bundled and combined for manufacturing plants, and indicate that higher levels of site competence lead to better performance in cost efficiency, quality, and new product introductions.

    Originality/value: We research patterns of site competence at a more detailed level than before, as well as study the impact on performance. The results provide empirical evidence that site competences come in bundles in three steps according to themes rather than individually.

    Keyword
    Empirical research, Manufacturing network, Operations strategy
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-68663 (URN)
    Available from: 2011-05-27 Created: 2011-05-27 Last updated: 2011-05-27Bibliographically approved
    4. Linking networks and plant roles: The impact of changing a plant role
    Open this publication in new window or tab >>Linking networks and plant roles: The impact of changing a plant role
    2013 (English)In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 51, no 19, 5696-5710 p.Article in journal (Refereed) Published
    Abstract [en]

    Many manufacturing firms are expanding their global footprint to explore new opportunities for efficient and effective production. The strategic perspective on international manufacturing networks involves both the network level and the plant level. A key aspect is the relationship between the network and the role of plants. In this research, we investigate the relationship between the network and plant perspectives in international manufacturing networks. We use an embedded case study that includes five plants in two product networks over a period of three years. We analyse how changing the role of one plant affects the network as well as the roles of the other plants in the networks. We find that decisions on plant roles are, to a very high degree, network decisions and not decisions for individual plants. Based on the insights into the case study, we also develop a framework for mapping manufacturing networks, including market coverage, plant location and site competence.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2013
    Keyword
    Case study, Global operations, International manufacturing, Longitudinal study, Manufacturing strategy
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-68668 (URN)10.1080/00207543.2013.778429 (DOI)000325069700003 ()
    Available from: 2011-05-27 Created: 2011-05-27 Last updated: 2013-11-08Bibliographically approved
    5. Distribution of Manufacturing Strategy Decision-Making in Manufacturing Networks
    Open this publication in new window or tab >>Distribution of Manufacturing Strategy Decision-Making in Manufacturing Networks
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper is concerned with manufacturing strategy decision-making. In particular, we study how strategic decisions are distributed between the network level and manufacturing plants in manufacturing networks. We use data from 107 manufacturing plants. This research shows that manufacturing strategy decisionmaking (in terms of decision categories and policy areas) can be divided into three difference types: centralized at the network level, decentralized at the plant level, and integrated between central headquarter and local plants. All decision categories follow the same structure, i.e. one of the three types is applied to all decision areas. Thus, we do not find support for that some decision areas are centralized while others are decentralized. The levels of site competences are significantly related to these decision-making patterns, such that plants with high levels of decision autonomy have significantly higher levels of site competences than plants with other decision-making structures.

    Keyword
    Decision categories, Exploratory study, Manufacturing strategy process, Survey research.
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-68664 (URN)
    Available from: 2011-05-27 Created: 2011-05-27 Last updated: 2011-05-27Bibliographically approved
    6. Testing a cumulative model of site competences
    Open this publication in new window or tab >>Testing a cumulative model of site competences
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper sets out to test the cumulative nature of site competences, also referred to as technical activities and their relationship to operational performance. Based on previeous identification of competence bundles, we specifically test the hypothesis that first production responsibilities are added at a plant then supply chain and finally  development responsibilities. We do this using structural equations modeling based on data from 109 Swedish plants. The results do not conclusively confirm a cumulative model, but give partial support for the hypothesis. There is also support for that higher degree of site competences can have a positive impact on certain aspects of operational performance.

    Keyword
    Plant role, cumulative competences, structural equations modeling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-68665 (URN)
    Available from: 2011-05-27 Created: 2011-05-27 Last updated: 2011-05-27Bibliographically approved
  • 41.
    Bexell, Jonas
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bjureus, Erik
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A study of energy exchange in earth air tubes2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As energy issues today are of great interest the writers of this report have done a research about an alternative to save energy by reducing the cost of preheating the outdoor air.

    By taking the outdoor air to the ventilation system via a pipe buried in the ground, you can preheat the outdoor air, which, in turn, could save energy. By doing this you do not have to bring as much energy to preheat the supply air, to get the desired supply air temperature. The report also explains if the earth air tubes are a good complement to the mechanical ventilation system with a heat exchanger.

    The report begins with describing briefly the history of ventilation systems in use today. It also describes the functions of the system and show to the reader how two of the installation layouts looks like.

    The writers using the project Daggkåpan in Linköping as a basis for the investigation and they also provide an alternative solution to the existing ventilation system.

    This report also demonstrate the factors that come into play to get as much energy exchange as possible, and what problems may arise with this type of complement to the ventilation system with a heat exchanger.

    Trough optimization of the earth air tubes and depending on which energy source is in use, you can actually save energy and by that also money. The factor that proved to bethe most significant for the energy exchange was the pipe length. Other factors such as trench depth, pipe diameter and the air flow has been shown to play a smaller role in how much energy you can save.

    Finally the report ends with the writers own reflections and a discussion based on the results.

  • 42.
    Kanesund, Jan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    A Study of the Influence of Plastic Pre Strain in Different Directions Before Ageing of Extruded and Hydro Formed Material on the Mechanical Properties of AA60632012Conference paper (Refereed)
  • 43.
    Edvardsson, Sverker
    et al.
    Mittuniversitetet, Institutionen för informationsteknologi och medier.
    Ojamäe, L
    Thomas, John O
    A study of vibrational modes in Na(+)beta-Alumina by molecular-dynamics simulation1994In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 6, no 7, 1319-1332 p.Article in journal (Refereed)
    Abstract [en]

    The vibrational properties of crystalline Na+ beta-alumina (Na1.22Al11O17.11) have been studied using the molecular dynamics simulation technique. The vibrational density of states was calculated from the velocity autocorrelation function, and the infrared spectrum from the dipole-dipole autocorrelation function. Knowledge of the vibrations in different crystallographic directions for the different atomic species facilitates the assignment of spectral peaks. The sodium in-plane vibrations are 59, 88 and 112 cm-1, and the out-of-plane vibrations are at 146 cm-1. The stoichiometric compound is also studied, and in this case the sodium in-plane vibrations are at 80 cm-1 and the out-of-plane vibrations at 140 cm-1. The density of states is used to calculate thermodynamic properties: heat capacity, entropy and internal and free energy. The values obtained at 300 K are C(upsilon) = 410 J K-1 mol-1, S(upsilon) = 300 J K-1 mol-1, U = 370 kJ mol-1 and F = 280 kJ mol 1. The heat capacity and entropy values are in good agreement with experiment, and thus strongly support the empirical force field used in the simulation

  • 44.
    Berntsson, Fredrik
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    A survey of methods for determinig surface temperatures using interior measurements2001In: Trends in Heat, Mass & Momentum Transfer, Vol. 7, no pp, 105-128 p.Article in journal (Refereed)
  • 45.
    Klugman, Sofia
    et al.
    University of Gävle.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    A Swedish integrated pulp and paper mill - Energy optimisation and local heat cooperation2009In: Energy Policy, ISSN 0301-4215, Vol. 37, no 7, 2514-2524 p.Article in journal (Refereed)
    Abstract [en]

    Heat cooperation between industries and district heating companies is often economically and environmentally beneficial. In this paper, energy cooperation between an integrated Swedish pulp and paper mill and two nearby energy companies was analysed through economic optimisations. The synergies of cooperation were evaluated through optimisations with different system perspectives. Three changes of the energy system and combinations of them were analysed. The changes were process integration, extending biofuel boiler and turbine capacity and connection to a local heat market. The results show that the single most promising system change is extending biofuel and turbine capacity. Process integration within the pulp and paper mill would take place through installing evaporation units that yield less excess heat but must in this particular case be combined with extended biofuel combustion capacity in order to be beneficial. Connecting to the local heat market would be beneficial for the pulp and paper mill, while the studied energy company needs to extend its biofuel capacity in order to benefit from the local heat market. Furthermore, the potential of reducing CO2 emissions through the energy cooperation is shown to be extensive; particularly if biofuel and turbine capacity is increased.

  • 46.
    Holmgren, Kristina
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    A System Perspective on District Heating and Waste Incineration2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Energy recovery by waste incineration has a double function as waste treatment method and supplier of electricity and/or heat, thereby linking the systems of energy and waste management. Both systems are undergoing great changes, mainly due to new regulations. Important regulations within waste management in Sweden are a ban on landfill of combustible waste and organic waste, and a tax on landfill of waste. New waste incineration facilities are being built in order to increase capacity to meet these demands.

    The aim of this thesis is to investigate impacts on Swedish district heating systems of increased use of waste as a fuel in economic and environmental terms, the latter mainly by assessing emissions of carbon dioxide. Of importance is the influence of various policy instruments. To highlight the connection between the energy and waste management systems and how these influence each other is another goal, as well as the function of district heating systems as user of various waste heat supplies. An important assumption for this thesis is a deregulated European electricity market, where the marginal power production in the short term is coal condensing power and in the long term natural gas based power, that affects the conditions for combined heat and power in district heating systems. The method used is case studies of three Swedish municipalities that utilise waste in their district heating systems. In two papers, the scope is broadened from the energy utility perspective by comparing the energy efficiency of energy recovery and material recovery of various fractions, and the effect of including external costs for CO2 as well as SO2, NOx and particles. The ambition is that the results can be part of the decision making process for energy utilities and for policy makers in the energy sector and waste management.

    It is economically advantageous to use waste as a fuel in the energy sector and regulations in the waste management sector and high taxes on fossil fuels contribute to profitability. Waste incineration plants are base suppliers of heat because they derive revenue from receiving the waste. Economic conditions for waste incineration are altered with the introduction of a tax on incinerated municipal waste. A conflict may arise between combined heat and power production in district heating systems and waste incineration, since the latter can remove the heat sink for other combined heat and power plants with higher efficiencies. Combined heat and power is the main measure to decrease carbon dioxide emissions in district heating systems on the assumption that locally produced electricity replaces electricity in coal condensing plants. It can be difficult to design policy instruments for waste incineration due to some conflicting goals for waste management and energy systems. Comparing the energy efficiency of material recovery and energy recovery is a way to assess the resource efficiency of waste treatment methods. From that perspective, if there is a district heating system which can utilise the heat, biodegradable waste and cardboard should be energy recovered and plastics and paper material recovered. To put costs on environmental effects, so called external costs, is a way to take these effects into regard in traditional economic calculations, but the method has drawbacks, e.g. the limited range of environmental effects included and uncertainties in the monetary valuation of environmental effects.

    List of papers
    1. Waste incineration in Swedish municipal energy systems: modelling the effects of various waste quantities in the city of Linköping
    Open this publication in new window or tab >>Waste incineration in Swedish municipal energy systems: modelling the effects of various waste quantities in the city of Linköping
    2004 (English)In: Sustainable development of energy, water and environment systems, Dubrovnik, Croatia; 2004, 2004Conference paper, Published paper (Other academic)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14201 (URN)
    Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2009-05-19
    2. Modelling a district heating system: introduction of waste incineration, policy instruments and co-operation with an industry
    Open this publication in new window or tab >>Modelling a district heating system: introduction of waste incineration, policy instruments and co-operation with an industry
    2004 (English)In: Energy Policy, ISSN 0301-4215, Vol. 32, no 16, 1807-1817 p.Article in journal (Refereed) Published
    Abstract [en]

    The capacity for waste incineration in Swedish municipalities is increasing due to regulations aimed at decreasing landfill with waste. This has a large impact on the municipal energy systems, since waste is an important fuel for district heating production. The object of this study is a municipality, Skövde, which is planning to build a waste incineration plant to produce electricity and heat. The municipality is also planning to extend the district heating grid to include a large industrial heat consumer. The economic effect on the energy system of these measures is analysed as well as environmental effects in terms of carbon dioxide emissions. The consequences of two different policy instruments, green electricity certificates and a tax on waste incineration, are also studied. Economic optimisations show that the advantage of co-operation with industry is twofold: lower heat production costs and a considerable reduction of carbon dioxide emissions. It is economically feasible to invest in a waste incineration plant for heat production. An important measure to lower carbon dioxide emissions is to introduce combined heat and power production on the assumption that locally produced electricity replaces electricity produced by coal condensing power.

    Keyword
    Waste, Energy recovery, District heating, Policy instruments, Industrial co-operation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14202 (URN)10.1016/S0301-4215(03)00168-X (DOI)
    Available from: 2007-01-04 Created: 2007-01-04
    3. Role of a district heating network as a user of waste heat supply from various sources: the case of Göteborg
    Open this publication in new window or tab >>Role of a district heating network as a user of waste heat supply from various sources: the case of Göteborg
    2006 (English)In: Applied Energy, ISSN 0306-2619, Vol. 83, no 12, 1351-1367 p.Article in journal (Refereed) Published
    Abstract [en]

    District-heating (DH) networks can utilise heat that would otherwise be of limited use. This study analyses a municipal DH system, which uses waste heat from industries and waste incineration as base suppliers of heat and is currently investing in a natural-gas fired combined heat-and-power (CHP) plant. An important assumption in this study is of the establishment of an integrated European electricity-market, which means higher electricity prices than are traditional in Sweden. The study shows that there is space in the DH system for all three energy carriers; heat from industries, waste incineration and CHP plants. The new CHP plant replaces mainly other heat sources, i.e., hot water boilers and heat pumps. The new CHP plant’s operating time is strongly dependent on the electricity price.

    Keyword
    District heating; Waste incineration; Cogeneration; Waste heat; Modelling; Policy instruments
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14203 (URN)10.1016/j.apenergy.2006.02.001 (DOI)
    Available from: 2007-01-04 Created: 2007-01-04
    4. Modelling the impact of policy instruments on district heating operations: experiences from Sweden
    Open this publication in new window or tab >>Modelling the impact of policy instruments on district heating operations: experiences from Sweden
    2006 (English)In: 10th International Symposium on District Heating and Cooling, Hanover, Germany, 2006Conference paper, Published paper (Refereed)
    Abstract [en]

    Emission allowances aim at reducing carbon dioxide emissions in the European Union. Feed-in tariffs and green certificates increase renewable electricity generation in some countries. Undesired energy carriers, such as fossil fuels, can be taxed to decrease consumption. In Sweden, monetary policy instruments have been used for many years, which has influenced district-heating utilities’ operations and investments.

    The energy system optimisation model MODEST may help elucidating the impact of policy instruments on choices of fuels and plants. The model can minimise operation and investment costs for satisfying district heating demand, considering revenues from electricity sales and waste reception. It has been used to analyse heat and electricity production for 50 local Swedish utilities. This paper shows how some plants, systems and policy instruments have been modelled and results from some case studies. It may help analysts who face policy instruments, which probably will have a growing influence on district heating operations.

    Policy instruments should reflect external costs and induce behaviour that is beneficial from an overall viewpoint. Swedish fossil-fuel taxes hampered cogeneration during many years. Earlier, fuel input could be freely allocated to output energy forms and wood was often used for heat production and coal for electricity generation to minimise taxes. Now, lower taxes promote fossil cogeneration but green certificates make it more profitable to invest in renewable electricity generation.

    Carbon dioxide emission allowances can reduce local emissions due to districtheating and electricity production significantly at current price levels but the impact depends on allowance price. With emission trading, investment in a natural-gas-fired cogeneration plant may be beneficial for some utilities due to high electricity prices in the European electricity market, partly caused by emission allowances.

    District-heating demand can enable utilisation of resources that otherwise would be of no value. A landfill ban now increases waste incineration, which may reduce industrial waste heat utilisation and heat disposal from cogeneration plants and thereby decrease electricity production. A tax on incinerated waste may reduce the profitability of investing in waste incineration.

    Keyword
    Energy policy, taxes, green certificates, emission allowances, CHP
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14204 (URN)
    Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2009-05-18Bibliographically approved
    5. Comparison between material and energy recovery of municipal waste from an energy perspective: A study of two Swedish municipalities
    Open this publication in new window or tab >>Comparison between material and energy recovery of municipal waste from an energy perspective: A study of two Swedish municipalities
    2004 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, Vol. 43, no 1, 51-73 p.Article in journal (Refereed) Published
    Abstract [en]

    The aim of this study is to compare material recovery to waste incineration with energy recovery from the criteria of energy efficiency. Material recovery saves virgin material and also energy since production processes using recovered material are less energy intensive than processes using virgin material, whereas energy recovery saves other fuels that differ among various energy systems. Optimisations are made for the district heating systems in two Swedish municipalities, showing that it is profitable for the energy utilities in the municipalities to invest in plants using waste as a fuel for electricity and heat production. The fuels replaced by the waste differ between the municipalities. For one it is mostly wood chips, and for the other, a lot of biomass is replaced, but the largest saving is in oil. Energy savings by material recycling of the waste are calculated. Non-combustible waste, such as metals and glass save energy in various extensions when material recycled, but give no heat contribution when incinerated. It is more complicated to compare material and energy recovery of combustible waste fractions, such as cardboard, paper, plastics and biodegradable waste since they can be recycled in both fashions. For these fractions it is important to consider the configuration of the energy system. The conclusions from the two municipalities are that even if there is a district heating system able to utilise the heat, from the energy-efficiency view point; paper and hard plastics should preferably be material recovered, whereas cardboard and biodegradable waste is more suited for energy recovery through waste incineration. These calculations are done with the assumption that biomass should be regarded as a limited resource and when saved eventually eliminates fossile fuel combustion in other facilities.

    Keyword
    Waste management, Material recovery, Waste incineration, Energy recovery, District heating, Energy savings
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14205 (URN)10.1016/j.resconrec.2004.05.001 (DOI)
    Available from: 2007-01-04 Created: 2007-01-04
    6. Internalising external costs of electricity and heat production in a municipal energy system
    Open this publication in new window or tab >>Internalising external costs of electricity and heat production in a municipal energy system
    2007 (English)In: Energy Policy, ISSN 0301-4215, Vol. 35, no 10, 5242-5253 p.Article in journal (Refereed) Published
    Abstract [en]

    Both energy supply and waste treatment give rise to negative effects on the environment, so-called external effects. In this study, monetary values on external costs collected from the EU′s ExternE project are used to evaluate inclusion of these costs in comparison with an energy utility perspective including present policy instruments. The studied object is a municipal district heating system with a waste incineration plant as the base supplier of heat. The evaluation concerns fuels used for heat production and total electricity production, for scenarios with external costs included and for a scenario using the present policy instrument.

    Impacts of assumptions on marginal power producers (coal or natural gas power plants) are investigated, since locally produced electricity is assumed to replace marginal power and thus is credited for the avoided burden. Varying levels of external costs for carbon dioxide emissions are analysed. The method used is an economic optimisation model, MODEST.

    The conclusion is that present policy instruments are strong incentives for cogeneration, even when external costs are included. Waste is fully utilised in all scenarios. In cases where coal is the marginal power producer, more electricity is produced; when natural gas is the marginal power producer, less is produced. There are several uncertainties in the data for external costs, both methodological and ethical. In the ExternE data, not all environmental impacts are included. For waste incineration, ashes are not included, and another difficulty is how to treat the avoided burden of other waste treatment methods.

    Keyword
    External costs, Combined heat and power, Waste incineration
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14206 (URN)10.1016/j.enpol.2007.04.026 (DOI)
    Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2013-05-22
    7. Energy recovery from waste incineration: linking the technical systems of energy and waste management
    Open this publication in new window or tab >>Energy recovery from waste incineration: linking the technical systems of energy and waste management
    2006 (English)In: Conservation and Recycling of Resources: New Research, Nova Publishers , 2006Chapter in book (Other (popular science, discussion, etc.))
    Place, publisher, year, edition, pages
    Nova Publishers, 2006
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14207 (URN)
    Available from: 2007-01-04 Created: 2007-01-04
  • 47.
    Martin, Michael
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Fonseca, Jorge
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    A Systematic Literature Review of Biofuel Synergies2010Report (Other academic)
    Abstract [en]

    Often biofuels are criticized in the media for their low production energy efficiency, environmental impacts and by using food for fuel production. An answer most critics rely on is stating how 2nd generation biofuels will solve all the problems the first generation biofuels possess. However, 1st generation biofuels must “pave the way” for 2nd generation biofuels. They can do this by providing the infrastructure, technology and knowledge provided by the fuels.

    In order to increase the efficiency of 1st generation biofuels, the theories of industrial symbiosis can be applied. Industrial symbiosis theories are designed to integrate production systems and other industries to improve energy efficiency and environmental performance. By integrating biofuel production systems, the by-products of biofuels can be used in subsequent processes. By making use of by-products, excess heat, etc. the energy efficiency can be improved and allow for more benefits including economic and environmental performance.

    Industrial symbiosis literature includes many examples of how industries can benefit from one another but does not include much literature on the integration of biofuels. Synergies do however exist as there are many by-products which are highly prized in other industries, e.g. glycerol and DDGS. The biofuels themselves can even be used in subsequent processes.

    The aim of producing this literature study is to find relevant biofuel synergies1 within various fields from scientific literature. By searching for keywords and combining these with keywords related to biofuel synergies we can review the extent and knowledge of synergies between external industries with biofuels, between biofuel industries and the use of their byproducts throughout various research fields.

    The main research questions to be answered are:

    • What do other research fields use biofuel by-products for?
    • What are the current trends for the use of biofuels and their by-products?
    • What substrates/by-products/wastes from other industries can be used for biofuel production?
    • Which synergies exist in the literature beyond those presented in other phases of the research project?
    • What are some potential uses for biofuels, their by-products and industrial wastes and utilities to integrate in symbiosis?
  • 48.
    Arhammar, C.
    et al.
    Sandvik Coromant, Sweden .
    Silvearv, F.
    Luleå University of Technology, Sweden .
    Bergman, A.
    Uppsala University, Sweden .
    Norgren, S.
    Sandvik Coromant, Sweden Uppsala University, Sweden .
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Ahuja, R.
    Uppsala University, Sweden .
    A theoretical study of possible point defects incorporated into alpha-alumina deposited by chemical vapor deposition2013In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 133, no 2, 1433- p.Article in journal (Refereed)
    Abstract [en]

    The energetics and electronic structure of carbon, chlorine, hydrogen, and sulfur in alpha-Al2O3 was investigated by first principles and thermodynamical calculations. These species are present in the gas phase during the synthesis of alpha-Al2O3 by chemical vapor deposition (CVD) but little is known of their solubility in this compound. The heat of formation from standard reference states of the elements varying the chemical potential of each element was calculated. An attempt to model the actual conditions in the CVD process was made, using the species and solid compounds present in a common CVD process as reference states. Our calculations suggest that sulfur from the catalyzing agent H2S will not solve in alpha-Al2O3 during deposition by CVD. It is found that the neutral chlorine and hydrogen interstitial defects display the lowest heat of formation, 281 and 280 kJ/mol, respectively, at the modeled CVD conditions. This energy is too high in order for neutral defects to form during CVD of alpha-Al2O3 at any significant amounts. The charged defects and their compensation were studied. Carbon substituting oxygen is found to be energetically favored under the modeled CVD conditions, considering carbon dioxide as competing species to solid solubility in alpha-Al2O3 at an energy of -128 kJ/mol. However, care needs to be taken when choosing the possible competing carbon-containing phases. Compensation of carbon substituting for oxygen by oxygen vacancies takes place at 110 kJ/mol from standard reference states, graphite, fcc-Al and O-2. The carbon solubility in Al2O3 is difficult to measure with standard analysis techniques such as X-ray diffraction and energy dispersive X-ray spectroscopy, but several stable compounds in the Al-C-O are available in the literature.

  • 49.
    Baniya, Bishal
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    A theoretical study of the potential for metal extraction from the incinerated ashes residing in Swedish landfills2013In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 34, no 7, 891-900 p.Article in journal (Refereed)
    Abstract [en]

    In Sweden, waste incineration has played a major role in sustainable waste management, as well as generating combined heat and electricity for many years. Incineration of combustible waste produces residues such as fly ash and bottom ash. The chemical composition of both ashes shows that they consist of bulk metals and scarce metals in significant quantity, in elemental form as well as in small metal pieces, which remain unsorted from the incinerated residues. This shows the potential for metal extraction from the ashes, which are deposited in Swedish landfills. Thus with the aim of quantifying selected metals (Al, Cu, Fe, Zn, Sb, Sn, Ni, Co, Mo, Ti and V), and assessing their flows and stocks in different deposits, this study has been carried out. Approximately 50% of grate plants and 30% of fluidized bed plant in Sweden were sampled for the study. The data collected from the sampled plants were the basis for the calculation of flow of ashes and metals through all the plants. First of all, annual metal flows for 19852010 were estimated, based on which accumulated stocks at different deposits were calculated.

  • 50.
    Aradi, B.
    et al.
    Budapest University of Technology and Economy.
    Gali, A.
    Research Group of the Hungarian Academy of Sciences.
    Deák, P.
    Budapest University of Technology and Economy.
    Lowther, J. E.
    University of the Witwatersrand.
    Son, N. T.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ab initio density-functional supercell calculations of hydrogen defects in cubic SiC2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 245202Article in journal (Refereed)
    Abstract [en]

    Based on ab initio density-functional calculations in supercells of 3C-SiC, the stable configurations of hydrogen and dihydrogen defects have been established. The calculated formation energies are used to give semiquantitative estimates for the concentration of hydrogen in SiC after chemical vapor deposition, low temperature H-plasma anneal, or heat treatment in high temperature hydrogen gas. Vibration frequencies, spin distributions, and occupation levels were also calculated in order to facilitate spectroscopic identification of these defects. (V+nH) complexes are suggested as the origin of some of the signals assigned earlier to pure vacancies. Qualitative extrapolation of our results to hexagonal polytypes explains observed electrical passivation effects of hydrogen.

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