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Wren, Joakim
Publications (10 of 43) Show all publications
Szabó, Z., Sjökvist, S., Gustavsson, T., Carleberg, P., Uppsäll, M., Wren, J., . . . Smedby, Ö. (2013). Intraoperativ visualisering av myokardiell perfusion i realtidmeaugmented reality temperatur monitorering-en experimentellstudie. In: : . Paper presented at Thoraxmötet, 16-18 oktober 2013, Linköping (pp. O2-O2).
Open this publication in new window or tab >>Intraoperativ visualisering av myokardiell perfusion i realtidmeaugmented reality temperatur monitorering-en experimentellstudie
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2013 (Swedish)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-99977 (URN)
Conference
Thoraxmötet, 16-18 oktober 2013, Linköping
Available from: 2013-10-24 Created: 2013-10-24 Last updated: 2013-11-05
Szabó, Z., Berg, S., Sjökvist, S., Gustafsson, T., Carleberg, P., Uppsäll, M., . . . Smedby, Ö. (2013). Real-time intraoperative visualization of myocardial circulation using augmented reality terperature display. The International Journal of Cardiovascular Imaging, 29(2), 521-528
Open this publication in new window or tab >>Real-time intraoperative visualization of myocardial circulation using augmented reality terperature display
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2013 (English)In: The International Journal of Cardiovascular Imaging, ISSN 1569-5794, E-ISSN 1875-8312, Vol. 29, no 2, p. 521-528Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer, 2013
Keywords
Augmented reality – Mixed reality – Myocardium – Ischemia – Infrared thermometry – Visualization
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-80802 (URN)10.1007/s10554-012-0094-5 (DOI)000314285500030 ()
Available from: 2012-08-30 Created: 2012-08-30 Last updated: 2017-12-07
Wren, J. (2011). Active Learning in Engineering Thermodynamics for FirstYear Students using a Project Approach. In: Jorge Bernardino and José Carlos Quadrado (Ed.), 39th International conference on Engineering Education, Lisbon, September 27-30, 2011: Global Engineering Recognition, Sustainability and Mobility. Paper presented at SEFI annual conference (pp. 748-754). Brussels: SEFI
Open this publication in new window or tab >>Active Learning in Engineering Thermodynamics for FirstYear Students using a Project Approach
2011 (English)In: 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, Published paper (Refereed)
Place, publisher, year, edition, pages
Brussels: SEFI, 2011
Keywords
Active Learning, Student centered learning, Engineering Thermodynamics, Project
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-73550 (URN)
Conference
SEFI annual conference
Available from: 2012-01-13 Created: 2012-01-09 Last updated: 2012-01-13Bibliographically approved
Nadali Najafabadi, H., Karlsson, M., Bradley, A., Wren, J., Utriainen, E. & Kinell, M. (2011). CFD Simulations Using Reduced Models for Film Cooling Design. In: 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2011: . Paper presented at 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 4–7 January 2011, Orlando, Florida (pp. AiAA 2011-710). American Institute of Aeronautics and Astronautics
Open this publication in new window or tab >>CFD Simulations Using Reduced Models for Film Cooling Design
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2011 (English)In: 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, Published 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.

Place, publisher, year, edition, pages
American Institute of Aeronautics and Astronautics, 2011
Keywords
Film Cooling, Gas Turbines, CFD
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-76905 (URN)10.2514/6.2011-710 (DOI)978-1-60086-950-1 (ISBN)
Conference
49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 4–7 January 2011, Orlando, Florida
Available from: 2012-04-24 Created: 2012-04-24 Last updated: 2016-05-11Bibliographically approved
Wren, J. & Renner, J. (2011). Enhancing Student Engagement – A CDIO Approach in anEngineering Physics Master Program. In: Natascha van Hattum-Janssen Rui M. Lima Dinis Carvalho (Ed.), Third International Symposium on Project Approaches in Engineering Education (PAEE’2011):Aligning Engineering Education with Engineering Challenges. Paper presented at Third International Symposium on Project Approaches in Engineering Education (PAEE’2011) (pp. 283-289).
Open this publication in new window or tab >>Enhancing Student Engagement – A CDIO Approach in anEngineering Physics Master Program
2011 (English)In: 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, Published paper (Refereed)
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-73560 (URN)978-989-8525-05-5 (ISBN)
Conference
Third International Symposium on Project Approaches in Engineering Education (PAEE’2011)
Available from: 2012-01-13 Created: 2012-01-09 Last updated: 2012-01-13Bibliographically approved
Bradley, A., Nadali Najafabadi, H., Karlsson, M., Wren, J., Utriainen, E. & Kinell, M. (2011). Towards Efficient CFD-Simulations of Engine LikeTurbine Guide Vane Film Cooling. Paper presented at 49th AIAA Aerospace Science Meeting including the New Horizons Forum and Aerospace Exposition, January 4-7, Orlando, Florida, USA. ARC Aerospace Research Central
Open this publication in new window or tab >>Towards Efficient CFD-Simulations of Engine LikeTurbine Guide Vane Film Cooling
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2011 (English)Conference paper, Published 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.

Place, publisher, year, edition, pages
ARC Aerospace Research Central, 2011
Keywords
Film cooling, gas turbines, CFD
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:liu:diva-75567 (URN)10.2514/6.2011-708 (DOI)978-1-60086-950-1 (ISBN)
Conference
49th AIAA Aerospace Science Meeting including the New Horizons Forum and Aerospace Exposition, January 4-7, Orlando, Florida, USA
Available from: 2012-03-08 Created: 2012-03-08 Last updated: 2016-03-14Bibliographically approved
Bradley, A. & Wren, J. (2010). Comparison of Correlations and Experiments for Prediction of Vane Film Cooling in Gas Turbines. Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Comparison of Correlations and Experiments for Prediction of Vane Film Cooling in Gas Turbines
2010 (English)Report (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.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. p. 9
Series
LIU-IEI-R ; 102
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-90037 (URN)LIU-IEI-R-10/0102-SE (ISRN)
Available from: 2013-03-18 Created: 2013-03-18 Last updated: 2013-03-18
Kinell, M., Utriainen, E., Hylén, J., Gustavsson, J., Bradley, A., Karlsson, M. & Wren, J. (2010). Fan Shaped And Cylindrical Holes Studied in a Vane Film Cooling Test Rig. In: Proceedings of the Asme Turbo Expo 2010, Vol 4, Pts a and B: . Paper presented at ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010; Glasgow; United Kingdom (pp. 1777-1784).
Open this publication in new window or tab >>Fan Shaped And Cylindrical Holes Studied in a Vane Film Cooling Test Rig
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2010 (English)In: Proceedings of the Asme Turbo Expo 2010, Vol 4, Pts a and B, 2010, p. 1777-1784Conference paper, Published 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.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-91707 (URN)10.1115/GT2010-23308 (DOI)000290693500155 ()978-0-7918-4399-4 (ISBN)978-0-7918-3872-3 (ISBN)
Conference
ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010; Glasgow; United Kingdom
Available from: 2013-04-30 Created: 2013-04-30 Last updated: 2016-03-14Bibliographically approved
Szabó, Z., Sjökvist, S., Gustafsson, T., Uppsäll, M., Wren, J., Berg, S., . . . Smedby, Ö. (2010). Real-time intraoperative visualization of myocardial circulation by augmented reality temperature display. In: Minimally invasive therapy and allied technologies: . Paper presented at 22nd International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norway (pp. 61-61). Informa Healthcare
Open this publication in new window or tab >>Real-time intraoperative visualization of myocardial circulation by augmented reality temperature display
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2010 (English)In: Minimally invasive therapy and allied technologies, Informa Healthcare, 2010, p. 61-61Conference paper, Oral presentation with published abstract (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.

Place, publisher, year, edition, pages
Informa Healthcare, 2010
Series
Minimally Invasive Therapy, ISSN 1364-5706 ; 19 Suppl 1
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-93659 (URN)10.3109/13645706.2010.500867 (DOI)
Conference
22nd International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norway
Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2014-03-06Bibliographically approved
Lantz, J., Gårdhagen, R., Wren, J. & Karlsson, M. (2009). Heating in a Stenosed Coronary Artery With Pulsating Flow and Non-Newtonian Viscosity. In: ASME 2008 Summer Bioengineering Conference: Parts A and B. Paper presented at 10th ASME Summer Bioengineering Conference, SBC2008; Marco Island, Florida, USA, June 25–29, 2008 (pp. 331-332). The American Society of Mechanical Engineers (ASME) (PART A)
Open this publication in new window or tab >>Heating in a Stenosed Coronary Artery With Pulsating Flow and Non-Newtonian Viscosity
2009 (English)In: ASME 2008 Summer Bioengineering Conference: Parts A and B, The American Society of Mechanical Engineers (ASME) , 2009, no PART A, p. 331-332Conference paper, Published 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.

Place, publisher, year, edition, pages
The American Society of Mechanical Engineers (ASME), 2009
National Category
Medical Biotechnology
Identifiers
urn:nbn:se:liu:diva-57047 (URN)10.1115/SBC2008-192532 (DOI)000263364700166 ()978-0-7918-4321-5 (ISBN)
Conference
10th ASME Summer Bioengineering Conference, SBC2008; Marco Island, Florida, USA, June 25–29, 2008
Available from: 2010-06-11 Created: 2010-06-09 Last updated: 2016-05-17Bibliographically approved
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