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  • 1.
    Bradley, Andreas
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Nadali Najafabadi, Hossein
    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.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Utriainen, Esa
    Kinell, Mats
    Towards Efficient CFD-Simulations of Engine LikeTurbine Guide Vane Film Cooling2011Conference paper (Other academic)
    Abstract [en]

    It is well known that the efficiency of a gas turbine can be increased by using higher combustion temperatures and that this demands improved cooling. This study focuses on strategies to decrease the turnaround time for numerical predictions of film cooling while keeping the ability to resolve details of the flow. Simulations have been carried out for a real vane geometry at close to engine-like conditions and results are compared with corresponding experiments. The investigation includes an un-cooled situation for aerodynamic validation and to determine baseline heat transfer coefficent. Simulations and experiments of film effectiveness and heat transfer coefficient and their dependence of blowing ratio are investigated.

  • 2.
    Bradley, Andreas
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Comparison of Correlations and Experiments for Prediction of Vane Film Cooling in Gas Turbines2010Report (Other academic)
    Abstract [en]

    In an earlier report by Bradley, a number of correlations from the open literature were presented and evaluated. All these correlations manage to accurately describe the film cooling eectiveness for the experiments they are based on, but there is doubts regarding the general predictive value of these correlations, especially for engine-like conditions. The correlations have now been analysed to investigate their predictive capabilities - especially the general applicability of correlations is in focus, for example for geometries or flow conditions slightly dierent than those for which the correlations were originally designed.

  • 3.
    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, p. 737-741Article 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.

  • 4.
    Eriksson, Ola
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    A finite element model for brain electrodes and its comparison with in-vitro albumin lesions1999In: Congress of the International Society for Neurosurgical Technology and Instrument Invention ISNTII,1999, 1999Conference paper (Other academic)
  • 5.
    Johansson, Johannes D.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Comparison between a detailed and a simplified finite element model of radio-frequency lesioning in the brain2004In: 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Fransisco, USA, 2004, Vol. 4, p. 2510-2513Conference paper (Refereed)
    Abstract [en]

    A detailed and a simplified model of a lesioning electrode was made using the finite element method. 15 simulations of the lesioning procedure were performed for each model and the resulting lesion volumes were compared in order to investigate if the simplified model is adequate. The simplified model resulted in a very slight overestimation of the volume compared to the detailed model. It was thus concluded that the simplified model is adequate for simulations.

  • 6.
    Johansson, Johannes D
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction2006In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, no 9, p. 757-766Article in journal (Refereed)
    Abstract [en]

    Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders. A small electrode is used to thermally coagulate malfunctioning tissue. Influence on lesion size from thermal and electric conductivity of the tissue, microvascular perfusion and preset electrode temperature was investigated using a finite-element model. Perfusion was modelled as an increased thermal conductivity in non-coagulated tissue. The parameters were analysed using a 24-factorial design (n = 16) and quadratic regression analysis (n = 47). Increased thermal conductivity of the tissue increased lesion volume, while increased perfusion decreased it since coagulation creates a thermally insulating layer due to the cessation of blood perfusion. These effects were strengthened with increased preset temperature. The electric conductivity had negligible effect. Simulations were found realistic compared to in vivo experimental lesions.

  • 7.
    Johansson, Johannes D.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Simulations of radio-frequency lesions with varying brain electrode dimensions2005In: 13th Nordic Baltic conference biomedical engineering and medical physics, Umeå, Sweden, 2005, Vol. 9, p. 62-63Conference paper (Refereed)
    Abstract [en]

    Radio-frequency (RF) lesioning in the

    brain was simulated using the finite element method

    (FEM). Heating for 60 s with temperature control in

    order to keep the tip at 80 °C was simulated. Length,

    L, (2 – 4 mm) and diameter, D, (0.5 – 2.5 mm) of the

    electrode tip were varied and the resulting lesion

    volumes were used to calculate a regression model:

    Lesion Volume = – 13.1D + 15.7LD + 13.1D2 mm3.

    The results can be useful for electrode design and

    prediction of lesion size.

  • 8.
    Johansson, Johannes D.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study2007In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 4, no 2, p. 87-95Article in journal (Refereed)
    Abstract [en]

    Radiofrequency lesioning of nuclei in the thalamus or the basal ganglia can be used to reduce symptoms caused by e.g. movement disorders such as Parkinson's disease. Enlarged cavities containing cerebrospinal fluid (CSF) are commonly present in the basal ganglia and tend to increase in size and number with age. Since the cavities have different electrical and thermal properties compared with brain tissue, it is likely that they can affect the lesioning process and thereby the treatment outcome. Computer simulations using the finite element method and in vitro experiments have been used to investigate the impact of cysts on lesions' size and shape. Simulations of the electric current and temperature distributions as well as convective movements have been conducted for various sizes, shapes and locations of the cysts as well as different target temperatures. Circulation of the CSF caused by the heating was found to spread heat effectively and the higher electric conductivity of the CSF increased heating of the cyst. These two effects were together able to greatly alter the resulting lesion size and shape when the cyst was in contact with the electrode tip. Similar results were obtained for the experiments.

  • 9.
    Johansson, Johannes D.
    et al.
    Tekniska fakulteten Biomedicinsk instrumentteknik.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Eriksson, Ola
    Tekniska fakulteten Biomedicinsk instrumentteknik.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Wårdell, Karin
    Tekniska fakulteten Biomedicinsk instrumentteknik.
    Finite element method simulations of radio-frequency lesions with varying brain electrode dimensions2005In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, 2005Conference paper (Other academic)
  • 10.
    Johansson, Johannes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, Department of Mechanical Engineering.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    FEM-modell för termisk koagulering i hjärnvävnad2003In: Svenska lakaresallskapets riksstamma,2003, 2003, p. 242-242Conference paper (Other academic)
  • 11.
    Johansson, Johannes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    The influence of CSF-filled cavities on radio-frequency lesions - a simulation study2006In: Congress of the European Society for Stereotactic and Functional Neurosurgery,2006, New York: Springer , 2006Conference paper (Other academic)
  • 12.
    Johansson, Johannes
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Eriksson, O.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Teoretisk och experimentell undersökning av värmekoagulation med radiofrekvent ström i hjärna2005Conference paper (Refereed)
  • 13.
    Johansson, Johannes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, Department of Mechanical Engineering.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Investigation of brain RF-lesion size by finite element simulations2004In: European Society for Stereotactic and Functional Neurosurgery ESSFN,2004, Wien: Springer Verlag , 2004, p. 932-932Conference paper (Other academic)
  • 14.
    Johansson, Johannes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Konvektiva flöden och deras termiska inverkan vid Radiofrekvenslesionering i hjärna2006In: Medicinteknikdagarna 2006,2006, 2006Conference paper (Other academic)
    Abstract [en]

       

  • 15.
    Kinell, Mats
    et al.
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Utriainen, Esa
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Hylén, Jonas
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Gustavsson, Jonas
    Florida Center for Advanced Aero-Propulsion Florida State University, College of Engineering Tallahassee, USA.
    Bradley, Andreas
    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.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Fan Shaped And Cylindrical Holes Studied in a Vane Film Cooling Test Rig2010In: Proceedings of the Asme Turbo Expo 2010, Vol 4, Pts a and B, 2010, p. 1777-1784Conference paper (Refereed)
    Abstract [en]

    In order to optimize the vane film cooling and thereby increase the efficiency of a gas turbine, different film cooling configurations were experimentally investigated. Dynamic similarity was obtained regarding main flow Reynolds number, airfoil pressure coefficient, adiabatic wall temperature and film cooling ejection ratio. The maximum reached Mach number was 0.52. The geometry of the test section, consisting of one vane and two flow paths, was modified in order to meet the dimensionless pressure coefficient distribution around the airfoil experienced by a full stage airfoil. This would ascertain that scaled but engine realistic pressure gradients would be achieved in the rig test.

    During the test, the cold airfoil was suddenly imposed to a hot main stream and the evaluation of both the film cooling effectiveness and the heat transfer coefficient distribution on the visiable surface could be done at one single test using timeresolved temperature measurements obtained through IR thermography. A high resolution MWIR camera was used together with a silicon viewing window. The post-processing allowed for corrections regarding emissions and determination of the desired parameters on the vane surface.

    Results, heat transfer coefficients and film cooling effectiveness, for fan shaped and cylindrical film cooling holes configurations are compared. The results show clear benefit of using shaped holes over cylindrical ditto, especially on the suction side where near hole film effectiveness is enhanced by approximately 25%, but the results also show that this benefit diminishes to nothing in the suction side trailing edge region.

    The local heat transfer coefficients are generally lower for the shaped hole configurations. Contrary to the film effectiveness the shaped holes configurations show lower heat transfer coefficients also at the suction side trailing edge region, making use of the shaped hole configurations superior to cylindrical ones as the heat flux to the surface is reduced.

    Numerical predictions using a boundary layer code, TEXSTAN, and CFD, for a smooth wall configuration corresponds well with the measured results.

  • 16.
    Lantz, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Gårdhagen, Roland
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wren, Joakim
    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.
    Heating in a Stenosed Coronary Artery With Pulsating Flow and Non-Newtonian Viscosity2009In: ASME 2008 Summer Bioengineering Conference: Parts A and B, The American Society of Mechanical Engineers (ASME) , 2009, no PART A, p. 331-332Conference paper (Refereed)
    Abstract [en]

    Cardiovascular disease is the most prevalent cause of death in the developed countries and most deaths are due to coronary atherosclerosis [1]. During the development of atherosclerosis, several stages can be distinguished including vulnerable plaque. This group of plaque has an inclination for erosion and rupture and is therefore of particular interest. Due to the inflammatory response of vulnerable plaque including an increased metabolism and thereby a locally increased temperature, it is possible to detect such warm cores by intracoronally temperature measurement under some prerequisitions. Temperature differences up to 2.2 K on the surface of carotid plaques have been measured [2], but the relation between plaque vulnerability, inflammatory response, temperature increase and possibility to detection by means of temperature measurement is far from fully perceived.

  • 17. Lorr, D
    et al.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Svanborg, Eva
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Clinical Neurophysiology. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurophysiology UHL.
    Temperature changes in different locations of the body in conjunction with sleep2004In: 17th Congress of the European Sleep Research Society,2004, 2004Conference paper (Refereed)
  • 18.
    Loyd, Dan
    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 .
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Ekvationer för att beräkna temperaturen i vävnader2004In: Svenska Läkaresällskapets Riksstämma,2004, 2004Conference paper (Other academic)
  • 19.
    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.
    Bradley, Andreas
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Utriainen, Esa
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Kinell, Mats
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    CFD Simulations Using Reduced Models for Film Cooling Design2011In: 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2011, American Institute of Aeronautics and Astronautics, 2011, p. AiAA 2011-710-Conference paper (Other academic)
    Abstract [en]

    Film cooling technologies are widely used for attaining high efficiency in gas turbine engines. In this study we have investigated the potential for reduced models to capture different aspects of film cooling by means of CFD at low turn-around time while maintaining the accuracy at a reasonable level. CFD simulations and experiments were carried out for an engine-like setting. Subsequently, the computational domain was reduced in two steps in order to decrease the simulation time. Results for all models are compared with experimental data, including aerodynamic validation, heat transfer coefficient and film effectiveness. The aerodynamic results are very similar for experiments and simulations, and the heat transfer coefficient and film cooling effectiveness showed similarities within the expected range. Thus, this strategy could be very useful for e.g. early vane and film cooling design.

  • 20.
    Szabó, Zoltan
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Sjökvist, Stefan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Gustavsson, Torbjörn
    Carleberg, Per
    Uppsäll, Magnus
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Berg, Sören
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Intraoperativ visualisering av myokardiell perfusion i realtidmeaugmented reality temperatur monitorering-en experimentellstudie2013Conference paper (Other academic)
  • 21.
    Szabó, Zoltán
    et al.
    Linköping University, Department of Medical and Health Sciences, Cardiothoracic Anaesthesia and Intensive care. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Berg, Sören
    Linköping University, Department of Medical and Health Sciences, Cardiothoracic Anaesthesia and Intensive care. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Sjökvist, Stefan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology. Thermirage AB, Linköping, Sweden.
    Gustafsson, Torbjörn
    Thermirage AB, Linköping.
    Carleberg, Per
    Thermirage AB, Linköping.
    Uppsäll, Magnus
    Thermirage AB, Linköping.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Real-time intraoperative visualization of myocardial circulation using augmented reality terperature display2013In: The International Journal of Cardiovascular Imaging, ISSN 1569-5794, E-ISSN 1875-8312, Vol. 29, no 2, p. 521-528Article in journal (Refereed)
    Abstract [en]

    For direct visualization of myocardial ischemia during cardiac surgery, we tested the feasibility of presenting infrared (IR) tissue temperature maps in situ during surgery. A new augmented reality (AR) system, consisting of an IR camera and an integrated projector having identical optical axes, was used, with a high resolution IR camera as control. The hearts of five pigs were exposed and an elastic band placed around the middle of the left anterior descending coronary artery to induce ischemia. A proximally placed ultrasound Doppler probe confirmed reduction of flow. Two periods of complete ischemia and reperfusion were studied in each heart. There was a significant decrease in IR-measured temperature distal to the occlusion, with subsequent return to baseline temperatures after reperfusion (baseline 36.9 ± 0.60 (mean ± SD) versus ischemia 34.1 ± 1.66 versus reperfusion 37.4 ± 0.48; p < 0.001), with no differences occurring in the non-occluded area. The AR presentation was clear and dynamic without delay, visualizing the temperature changes produced by manipulation of the coronary blood flow, and showed concentrically arranged penumbra zones during ischemia. Surface myocardial temperature changes could be assessed quantitatively and visualized in situ during ischemia and subsequent reperfusion. This method shows potential as a rapid and simple way of following myocardial perfusion during cardiac surgery. The dynamics in the penumbra zone could potentially be used for visualizing the effect of therapy on intraoperative ischemia during cardiac surgery.

  • 22.
    Szabó, Zoltán
    et al.
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Sjökvist, Stefan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Gustafsson, Torbjörn
    Thermirage AB, Linköping, Sweden.
    Uppsäll, Magnus
    Thermirage AB, Linköping, Sweden.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Berg, Sören
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Smedby, Örjan
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Real-time intraoperative visualization of myocardial circulation by augmented reality temperature display2010In: Minimally invasive therapy and allied technologies, Informa Healthcare, 2010, p. 61-61Conference paper (Other academic)
    Abstract [en]

    Background:  Intraoperative  ischemia   during   coronary   surgery   may   have   severe   consequences   for the patient and may also pose a difficult diagnostic problem  to the  surgeon.  There  is no  clinically used direct  method  to evaluate  the  effect on  the  circulation of various therapeutic maneuvers  to the heart. Augmented (mixed)  reality using projection  of color- coded  infra-red  (IR)  images onto  the imaged  tissues in real  time  may  give an  intuitive  representation of the tissue surface temperature and thus,  information about   myocardial   perfusion   on  the  surface  of  the organ itself.

    Purpose:  To demonstrate in animal experiments the feasibility of presenting  IR tissue temperature images  reflecting  myocardial  perfusion into  the  surgical  field  with  augmented reality.

    Method: We  have  constructed a  system  consisting of an IR camera  and  a projector  integrated in such a way that  they  have  identical  optical  axes,  solving the  geometrical  correspondence problem  in an easy way. In 5 pigs (weight = 57.5 ± 7 kg), the thorax was opened    by   median    sternotomy.   After   exposing the  heart,  an  elastic  vessel loop  was placed  around the  middle  of  the  left  descending  coronary  artery. A  2  mm   ultrasound  probe   was  inserted   distally around the LAD for flow velocity measurements. Subsequent ischemia-reperfusion periods  were induced using a fixed protocol. 

    Results:  The  time course of  an   occlusion   was  clearly  seen   in  quantitative curves  as well as in  color-coded temperature  maps on the surface of the heart.  The  difference in surface temperature between the three areas more or less affected  by  the  ischemia   was  also  clearly  demon- strated.  During  ischemia,  the surface of the myocardium  showed  concentrically  arranged  zones  of different temperatures (IR penumbra) potentially cor- responding to different  degrees  of severity of ischemia. 

    Conclusion: Surface  temperature changes  due to ischemia can be assessed quantitatively and visualized  in situ during occlusion of a coronary  artery and   subsequent  reperfusion of  the myocardium. This method shows potential  as  a  fast  and  simple way of  following  myocardial  perfusion  during surgery. The  change  of the  extension  of the  penumbra zone  is a potential monitoring device  for the  thera- pies used  in the salvage or prevention of ischemia  in experimental or clinical cardiac surgery and may introduce new practices in monitoring  duringcardiac  and vascular anesthesia.

  • 23.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Active Learning in Engineering Thermodynamics for FirstYear Students using a Project Approach2011In: 39th International conference on Engineering Education, Lisbon, September 27-30, 2011: Global Engineering Recognition, Sustainability and Mobility / [ed] Jorge Bernardino and José Carlos Quadrado, Brussels: SEFI , 2011, p. 748-754Conference paper (Refereed)
  • 24.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Evaluation of three temperature measurement methods used during microwave thermotherapy of prostatic enlargement2004In: International Journal of Hyperthermia, ISSN 0265-6736, E-ISSN 1464-5157, Vol. 20, no 3, p. 300-316Article in journal (Refereed)
    Abstract [en]

    Three temperature measurement methods used during microwave thermotherapy of prostatic enlargement are analysed and evaluated using a phantom model. A commercial transurethral microwave thermotherapy (TUMT) system that uses a radiometric thermometer for temperature control was used to heat the phantom. The transient temperature distribution was obtained by using both fibreoptic (which is considered as gold standard) and thermocouple measurements. Both methods are subject to potential measurement errors caused by electro-magnetic and/or thermal interference. The error sources are analysed and the measurement methods evaluated. The radiometric temperature and especially its relation to the transient temperature distribution was evaluated based on the fibreoptic and thermocouple measurements. These measurements in principle gave equivalent temperature distributions, and thermal interference was concluded to be the largest source of measurement error. The radiometric measurement method gave qualitative rather than quantitative readings of the temperature, and an underestimation of more than 10°C was obtained for some parts of the heated area. The area that gives most of the radiometric signal was relatively close to the catheter in contrast to previously published results.

  • 25.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Microwave Thermotherapy of Prostatic Enlargement, Analysis of Radiometric Thermometry using a Hybrid Bio-Heat Equation2004In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 7, no 3Article in journal (Refereed)
  • 26.
    Wren, Joakim
    Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    On modelling and simulation of perfused tissue during thermal treatment: thermal analysis of blood perfusion and lesioning during ablative neurosurgery2000Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Thermal treatment means therapy for which heat is the therapeutic agent. During treatment, the tissue temperature is increased to an injurious temperature (higher than 43 °C for the most widely used treatments). The aim is to reach necrotic temperature in the treatment area and non-lethal temperature outside the same. However, for several reasons this is not possible.

    The thesis deals with thermal treatment from a thermal point of view. The principle aim of the analysis is to obtain the entire temperature field in the treatment area, preferably before the treatment even takes place (temperature prediction). However, it is a complex task to obtain the entire temperature fields which usually varies substantially with both time and space. Parameters of importance are for instance the power supply needed for a certain treatment, the blood perfusion and the heat flux within the treatment area.

    The thesis comprises two different projects; the first project regards modelling and simulation of heat transfer in blood-perfused tissue. The second project concerns modelling and simulation of lesion growth and associated thermal problems during ablative neurosurgery. Throughout the thesis the focus is on modelling, but also experiments are carried out in order to enhance the thermal analysis in the second project.

    In the first project, an important aim is to increase the understanding about the equations (bio-heat equations, BHE's) used for modelling the effect from blood perfusion. A survey as well as a discussion of the equations used the last few decades is carried out. The core of the project is to the BHE's that are variants of the heat conduction equation, and therefore easily implemented in standard thermal simulation packages. An alternative model is proposed in the thesis as a more accurate and flexible tool compared with the most widely used models, the BHE of Pennes and the keff equation.

    In the second project, the focus is on the lesion growth together with the very important temperature measurement, which is used to monitor and control the lesioning process. A simulation model is developed by using input from the in vitro experiments. The model is considered to accurately describe the lesioning process, and very good agreement between experiments and simulations is obtained.

    Furthermore, simulations are used to analyse and evaluate the intra-electrode temperature measurement. The maximum temperature was always located outside the electrode, and therefore, there is always a difference in both time and level between the measured temperature and maximum temperature in the treatment area. The difference is important to quantify, since the lesioning process is directly dependent on the temperature measurement.

  • 27.
    Wren, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Andersson, P.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Radiofrequency Thermal Ablation of Liver Tumors: Impact of Large Vessels2009In: ASME 2008 Summer Bioengineering Conference: Parts A and B, The American Society of Mechanical Engineers (ASME) , 2009, no PART B, p. 611-612Conference paper (Refereed)
    Abstract [en]

    Surgical resection is the golden standard for treatment of both primary and metastatic liver tumors, and the method is associated with the highest long-time survival rates [1]. A large number of patients are however not candidates for tumor resection, for example due to un-sufficent hepatic reserve or tumor location relative to large blood vessels. In those cases, an alternative treatment strategy is to heat the tumor(s) to lethal temperatures by means of Radiofrequency (RF) current.

  • 28.
    Wren, Joakim
    et al.
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    Analysis of temperature measurement for monitoring radio-frequency brain lesioning2001In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 39, no 2, p. 255-262Article in journal (Refereed)
    Abstract [en]

    During ablative neurosurgery of movement disorders, for instance therapy of Parkinson's disease, temperature monitoring is crucial. This study aims at a quantitative comparison of measurement deviations between the maximum temperature located outside the lesioning electrode and two possible thermocouple locations inside the electrode. In order to obtain the detailed temperature field necessary for the analysis, four finite element models associated with different surroundings and with different power supplies are studied. The results from the simulations show that both the power level and the power density as well as the surrounding medium affect the temperature measurement and the temperature field in general. Since the maximum temperature is located outside the electrode there will always be a deviation in time and level between the measured and the maximum temperature. The deviation is usually 2–7 s and 3–12°C, depending on, for example, the thermocouple location and surrounding medium. Therefore, not only the measured temperature but also the relation between measured and maximum temperature must be accounted for during therapy and device design.

  • 29.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Erlandsson, B-E
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Simulation of thermal treatment of the prostate using a hybrid bio-heat equation2001In: International Symposium on Computer Methods in Biomechanics and Biomedical Engineering,2001, 2001Conference paper (Refereed)
  • 30.
    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.
    heat transfer analysis model of microwave thermal therapy of the prostate2000In: World Congress on Medical Physics and Biomedical Engineering,2000, 2000Conference paper (Refereed)
  • 31.
    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, E-ISSN 1464-5157, Vol. 17, no 6, p. 483-498Article 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.

  • 32.
    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.
    Transient temperature response of the myocardium investigated by the hybrid bioheat model2004In: IASME Transactions, ISSN 1790-031X, Vol. 1, no 3, p. 560-565Article in journal (Refereed)
  • 33.
    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)
  • 34.
    Wren, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Andersson, U.
    Vattenfall Utveckling AB, Älvkarleby, Sweden.
    Karlsson, R.
    Chalmers University of Technology, Gothenburg, Sweden.
    Thermally induced convective movements in a standard experimental model for characterization of lesions prior to radiofrequency functional neurosurgery2007In: Journal of Biomechanical Engineering, ISSN 0148-0731, E-ISSN 1528-8951, Vol. 129, no 1, p. 26-32Article in journal (Refereed)
    Abstract [en]

    Experimental exploration of equipment for stereotactic functional neurosurgery based on heating induced by radio-frequency current is most often carried out prior to surgery in order to secure a correct function of the equipment. The experiments are normally conducted in an experimental model including an albumin solution in which the treatment electrode is submerged, followed by a heating session during which a protein clot is generated around the electrode tip. The clot is believed to reflect the lesion generated in the brain during treatment. It is thereby presupposed that both the thermal and electric properties of the model are similar to brain tissue. This study investigates the presence of convective movements in the albumin solution using laser Doppler velocimetry. The result clearly shows that convective movements that depend on the time dependent heating characteristics of the equipment arise in the solution upon heating. The convective movements detected show a clear discrepancy compared with the in vivo situation that the experimental model tries to mimic, both the velocity (maximum velocity of about 5 mm/s) and mass flux are greater in this experimental setting. Furthermore the flow geometry is completely different since only a small fraction of the tissue surrounding the electrode in vivo consists of moving blood, whereas the entire surrounding given by the albumin solution in the experimental model is moving. Earlier investigations by our group (Eriksson et al., 1999, Med. Biol. Eng. Comput. 37, pp. 737-741, Wren, 2001, Ph.D. thesis, and Wren et al., 2001, Med. Biol. Eng. Comput. 39, pp. 255-262) indicate that the heat flux is an essential parameter for the lesion growth and final size, and that presence of convective movements in the model might substantially increase the heat flux. Thus, convective movements of the magnitude presented here will very likely underestimate the size of the brain lesion, a finding that definitely should be taken into consideration when using the model prior to patient treatment. Copyright © 2007 by ASME.

  • 35.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Loyd, Dan
    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 .
    Investigation of medical thermal treatment using a hybrid bio-heat model2004In: 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society,2004, 2004Conference paper (Refereed)
  • 36.
    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, p. 46-Conference paper (Refereed)
    Abstract [en]

      

  • 37.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Persson, Peter
    IKP .
    Thermostatic mixing valves - A method for non-disturbing intra-valve heat transfer estimation2006In: Journal of Advanced Nursing, ISSN 0309-2402, E-ISSN 1365-2648, Vol. 1, p. 59-64Article in journal (Refereed)
    Abstract [en]

      

  • 38.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Persson, Peter
    IKP .
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Thermostatic Mixing Valves - Modeling and simulation of the thermostat under real operating conditions2006In: WSEAS Transactions on Circuits and Systems, ISSN 1109-2734, Vol. 1, p. 56-61Article in journal (Refereed)
    Abstract [en]

       

  • 39.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Persson, Peter
    IKP .
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Thermostatic Mixing Valves - Thermostatic temperature distribution during various operating conditions2006In: International Conference on Heat and Mass Transfer,2006, Miami, Florida, Usa: WSEAS/IASME , 2006, p. 42-Conference paper (Refereed)
    Abstract [en]

      

  • 40.
    Wren, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Renner, Johan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Enhancing Student Engagement – A CDIO Approach in anEngineering Physics Master Program2011In: Third International Symposium on Project Approaches in Engineering Education (PAEE’2011):Aligning Engineering Education with Engineering Challenges / [ed] Natascha van Hattum-Janssen Rui M. Lima Dinis Carvalho, 2011, p. 283-289Conference paper (Refereed)
  • 41.
    Wren, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Renner, Johan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Gårdhagen, Roland
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Johansson, Kristina
    n/a.
    Learning More with Demonstration Based Education2009In: INTERNATIONAL JOURNAL OF ENGINEERING EDUCATION, ISSN 0949-149X, Vol. 25, no 2, p. 374-380Article in journal (Refereed)
    Abstract [en]

    The purpose of this case study is to present an alternative way of teaching, using demonstrations as a teaching aid. A system for visualisation and demonstration of fluid mechanics, particularly laminar and turbulent flow, has been dei,eloped, used, and evaluated in a basic fluid mechanics course for students in Mechanical Engineering. The idea underlying the demonstrations was to enhance the students conceptual understanding of phenomena that emerged in fluid mechanics. In order to investigate the outcome, we asked the students from two different groups to fill out a questionnaire in a cross-sectional manner. The results indicate that demonstration-based education had increased the students motivation and probably enhanced their learning. This could imply that the student moved from a surface approach to a deep-level approach to learning.

  • 42.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Sjödin, Jan-Gunnar
    Erlandsson, Björn-Erik
    Eliasson, Tomas
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Accuracy of Temperature Measurement During Transurethral Hyperthermia Treatment och the Prostate1999In: Proc of BMES/BMBS99,1999, 1999Conference paper (Other academic)
  • 43.
    Wren, Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Svensson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Gårdhagen, Roland
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Engstrand, Ulf
    Learning more with demonstration based education2005In: CUL-dagen 2005,2005, 2005Conference paper (Other academic)
1 - 43 of 43
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