liu.seSearch for publications in DiVA
Change search
Refine search result
4567 301 - 320 of 320
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 301.
    Thollander, Patrik
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Palm, Jenny
    IIIEE, International Institute for Industrial Environmental Economics, Lund University, Lund, Sweden.
    Hedbrant, Johan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering.
    Energy Efficiency as a Wicked Problem2019In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 11, no 6, article id 1569Article in journal (Refereed)
    Abstract [en]

    Together with increased shares of renewable energy supply, improved energy efficiency is the foremost means of mitigating climate change. However, the energy efficiency potential is far from being realized, which is commonly explained by the existence of various barriers to energy efficiency. Initially mentioned by Churchman, the term “wicked problems” became established in the 1970s, meaning a kind of problem that has a resistance to resolution because of incomplete, contradictory, or changing requirements. In the academic literature, wicked problems have later served as a critical model in the understanding of various challenges related to society, such as for example climate change mitigation. This aim of this paper is to analyze how the perspective of wicked problems can contribute to an enhanced understanding of improved energy efficiency. The paper draws examples from the manufacturing sector. Results indicate that standalone technology improvements as well as energy management and energy policy programs giving emphasis to standalone technology improvements may not represent a stronger form of a wicked problem as such. Rather, it seems to be the actual decision-making process involving values among the decision makers as well as the level of needed knowledge involved in decision-making that give rise to the “wickedness”. The analysis shows that wicked problems arise in socio-technical settings involving several components such as technology, systems, institutions, and people, which make post-normal science a needed approach.

    Download full text (pdf)
    Energy Efficiency as a Wicked Problem
  • 302.
    Thore, Carl-Johan
    et al.
    Linköping University, Department of Management and Engineering, Mechanics . Linköping University, The Institute of Technology.
    Stålhand, Jonas
    Linköping University, Department of Management and Engineering, 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.
    Toward a noninvasive subject-specific estimation of abdominal aortic pressure2008In: American Journal of Physiology. Heart and Circulatory Physiology, ISSN 0363-6135, E-ISSN 1522-1539, Vol. 295, no 3Article in journal (Refereed)
    Abstract [en]

    A method for estimation of central arterial pressure based on linear one-dimensional wave propagation theory is presented in this paper. The equations are applied to a distributed model of the arterial tree, truncated by three-element windkessels. To reflect individual differences in the properties of the arterial trees, we pose a minimization problem from which individual parameters are identified. The idea is to take a measured waveform in a peripheral artery and use it as input to the model. The model subsequently predicts the corresponding waveform in another peripheral artery in which a measurement has also been made, and the arterial tree model is then calibrated in such a way that the computed waveform matches its measured counterpart. For the purpose of validation, invasively recorded abdominal aortic, brachial, and femoral pressures in nine healthy subjects are used. The results show that the proposed method estimates the abdominal aortic pressure wave with good accuracy. The root mean square error (RMSE) of the estimated waveforms was 1.61 ± 0.73 mmHg, whereas the errors in systolic and pulse pressure were 2.32 ± 1.74 and 3.73 ± 2.04 mmHg, respectively. These results are compared with another recently proposed method based on a signal processing technique, and it is shown that our method yields a significantly (P < 0.01) lower RMSE. With more extensive validation, the method may eventually be used in clinical practice to provide detailed, almost individual, specific information as a valuable basis for decision making. Copyright © 2008 the American Physiological Society.

  • 303.
    Timgren, Marcus
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Coupled CFD and thermomechanical analysis of cooling in a die quenching tool2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the vehicle industry today materials are sought that are both light and have a high strength. One manufacturing method that can produce parts with both these properties is a method called die quenching. During die tool development simulations are used to predict the material properties in the final part and there is a continuous strive for improving the simulation tools. The aim of this report is to demonstrate how a CFD (Computational Fluid Dynamics) problem and a conjugate heat transfer problem can be set up in LS-DYNA and to evaluate how well the simulation results agree with experimental results. Simulations of the cooling of the die quenching is a first step towards performing a complete mechanical forming simulation that is coupled with CFD analysis in order to predict the final part’s material properties more accurately.

    In the thesis two experiments were simulated. To be able to perform such an analysis a conjugate heat transfer analysis is needed, in the thesis a heated cube was studied because it had experimental values for the temperature available. The flow in a quenching tool is also discussed and the pressure drop in the tool is compared with experimental values. Temperatures from the conjugate heat transfer are compared with experimental values and sources of errors are discussed in both simulations. The conclusion of this report is that the CFD solver in LS-DYNA is a promising tool that can be used to determine more accurate material properties of the final parts in a coupled thermomechanical forming simulation.

    Download full text (pdf)
    Coupled CFD and thermomechanical analysis of cooling in a die quenching tool
  • 304.
    Wahlbom Hellström, Victoria
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Alenius, Frida
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Investigation of Scale Adaptive Simulation (SAS) Turbulence Modelling for CFD-Applications2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fluid dynamics simulations generally require large computational recourses in form of computer power and time. There are different methods for simulating fluid flows that are more or less demanding, but also more or less accurate. Two well known computational methods are the Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES). RANS computes the timeaveraged flow properties, while LES resolve the large structures (eddies) of the flow directly and model the small ones. Hybrid models are combinations of these two models which have been developed to improve the RANS solutions and shorten the simulation time compared to LES computations. One such model is the Scale Adaptive Simulation (SAS) model which uses the RANS model in steady flow regions, such as close to walls, and a LES like model in unsteady regions with large fluctuations.

    This study was done for evaluating the SAS model compared to Unsteady RANS (URANS) and LES and their performance compared to measurements from an engineering point of view. This was done by running simulations on two different test cases, one external and one internal flow situation. The first one was flow around a wall-mounted cylinder and the second one was flow through an aorta with a coarctation in the descending aorta. The first test case was used to thoroughly evaluate the SAS model by running many simulations with URANS, SAS and LES with different element types, element sizes and flow parameters. The element types that have been analyzed are; tetrahedral, hexahedral and polyhedral. The results were compared with experiments done by Sumner et al. [7, 8, 9, 10]. The second test case was used for evaluating the SAS model even further on another flow situation. For this test case, only two SAS simulations were performed on two different grids; a structured hexahedral and an unstructured polyhedral. These results were compared with Magnetic Resonance Imaging (MRI) measurements obtained from Linköping University.

    No conclusion of which one of the simulated cases gives the best overall agreement with experimental results could be concluded from the obtained results. The best prediction of the drag coefficient for the cylinder was obtained for the coarsest polyhedral mesh that was run with LES, with the disagreement 0.4 percent. The best prediction of the Strouhal number was obtained for a URANS simulation performed on the coarsest mesh with an improved grid close to the cylinder surface, generating less than one, with a disagreement of 3 percent compared to measurements. For the meshes used, it was found that the polyhedral mesh gave the best overall results and the tetrahedral mesh gave the worst results for the cylinder case. For the aorta case the SAS model produced velocity components that had acceptable agreement with the MRI-measurements, but gave very poor results for the turbulent kinetic energy. The main conclusion of this thesis was that the SAS model performed better than URANS, but took longer time to compute simulations than LES, which was the model that generated the best overall results.

    Download full text (pdf)
    SAS
  • 305.
    Wang, Lieke
    et al.
    Siemens Ind Turbomachinery AB, Sweden.
    Kinell, Mats
    Siemens Ind Turbomachinery AB, Sweden.
    Nadali Najafabadi, Hossein
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering.
    A THREE-REGIME BASED METHOD FOR CORRELATING FILM COOLING EFFECTIVENESS FOR CYLINDRICAL AND SHAPED HOLES2015In: ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 5B, AMER SOC MECHANICAL ENGINEERS , 2015, no UNSP V05BT12A004Conference paper (Refereed)
    Abstract [en]

    To cope with high temperature of the gas from combustor, cooling is often used in the hot gas components in gas turbines. Film cooling is one of the effective methods used in this application. Both cylindrical and fan-shaped holes are used in film cooling. There have been a number of correlations published for both cylindrical and fan-shaped holes regarding film cooling effectiveness. Unfortunately there are no definitive correlations for either cylindrical or fan-shaped holes. This is due to the nature of the complexity of film cooling where many factors influence its performance, e.g., blowing ratio, density ratio, surface angle, downstream distance, expansion angle, hole length, turbulence level, etc. A test rig using infrared camera was built to test the film cooling performance for a scaled geometry from a real nozzle guide vane. Both cylindrical and fan-shaped holes were tested. To correlate the experimental data, a three-regime based method was developed for predicting the film cooling effectiveness. Based on the blowing ratio, the proposed method divides the film cooling performance in three regimes: fully attached (or no jet lift-off), fully jet lift-off, and the transition regime in between. Two separate correlations are developed for fully attached and full jet lift-off regimes, respectively. The method of interpolation from these two regimes is used to predict the film cooling effectiveness for the transition regime, based on the blowing ratio. It has been found this method can give a good correlation to match the experimental data, for both cylindrical and fan-shaped holes. A comparison with literature was also carried out, and it showed a good agreement.

  • 306.
    Wranne, Bengt
    et al.
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. 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.
    Analysis of different methods of assessing the stenotic mitral valve area with emphasis on the pressure gradient half-time concept.1990In: American Journal of Cardiology, ISSN 0002-9149, E-ISSN 1879-1913, Vol. 66, no 5, p. 614-620Article in journal (Refereed)
    Abstract [en]

    There are 2 different theoretical models that analyze factors influencing the transmitral pressure gradient half-time (T1/2), defined as the time needed for the pressure gradient to reach half its initial value. In this report the models and the assumptions inherent in them were summarized. One model includes left heart chamber compliance, the other does not. Although the models at a superficial glance seem to be contradictory, the conclusions drawn from them are similar: i.e., T1/2 is influenced not only by valve area, but also by initial maximal pressure gradient and by flow. Different clinical situations in which the T1/2 method for valve area estimation has been shown not to work are analyzed in the 2 models. It is concluded that these models have contributed to our understanding of the T1/2 concept and when it should not be used. We also advocate use of the continuity equation in these situations, since no assumptions then need be made.

  • 307.
    Wranne, Bengt
    et al.
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. 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.
    Problems related to the assessment of fluid velocity and volume flow in valve regurgitation using ultrasound Doppler technique.1987In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 8 Suppl C, p. 29-33Article in journal (Refereed)
    Abstract [en]

    Understanding of the factors affecting regurgitant flow through a heart valve and of the inherent limitations of the Doppler technique is needed to interpret correctly the information obtained during an ultrasound Doppler examination. This paper describes the flow conditions at the leaking valve and limitations of the Doppler technique which become important in the case of valve regurgitation. The flow conditions can be described in the following terms: contraction of the flow, core flow dimensions, friction, and intrusion and width of the jet flow. Contraction occurs at the entrance to the orifice and causes the width of the jet at the orifice to be smaller than the orifice itself. This contraction should be taken into account when calculating volume flow. The jet reaches a minimal area at the vena contracta where the flow velocity is close to that expected from the Bernoulli equation. The area of the vena contracta relative to the area of the hole can vary between 0.6 and 1.0; the lowest value is seen at a sharp-edged orifice and the highest value, at a hole with an ideally rounded inlet. Friction has a marginal role on flow velocity at the vena contracta. The velocity at the vena contracta persists in a region called the core flow region. This region has a length of 4-8 hole diameters. The total jet intrusion and the width of the jet are related to both the flow velocity at the hole and the diameter of the hole.(ABSTRACT TRUNCATED AT 250 WORDS)

  • 308.
    Wranne, Bengt
    et al.
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. 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.
    Quantification of heart valve regurgitation: a critical analysis from a theoretical and experimental point of view.1985In: Clinical Physiology, ISSN 0144-5979, E-ISSN 1365-2281, Vol. 5, no 1, p. 81-88Article in journal (Refereed)
    Abstract [en]

    A theoretical analysis is presented regarding factors of importance for the determination of distance of intrusion of the regurgitant jet in heart valve regurgitation. The analysis is based on hydrodynamic theory. In the idealized model situation, for a circular hole, the intrusion of the regurgitant jet is linearly related to the product of the fluid mean velocity in the orifice and the diameter of the orifice. This was also shown to be true in an experimental fluid model. Thus, volume regurgitation cannot be quantified by the measurement of distance of intrusion of the regurgitant jet alone. On the other hand, an estimate of volume regurgitation can, in the idealized situation, be obtained if mean fluid velocity in the orifice, distance of intrusion of the jet and regurgitation time are known.

  • 309.
    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)
    Download full text (pdf)
    Paper
  • 310.
    Wren, Joakim
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering.
    ENGINEERING THERMODYNAMICS IN THE 21ST CENTURY: ACTIVE LEARNING BY HUMAN BODY THERMODYNAMICS2015In: 2015 IEEE CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION (CVPR), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    A new project on human body thermodynamics was developed and used in traditional engineering thermodynamics courses. The aim was to increase student motivation and learning by making the students more active and in charge of their learning, and to widen the application of thermodynamics outside the engineering field. The students and teachers experiences were investigated using a combination of questionnaires and interviews. It was found that the students were relatively satisfied with the project, although there was a relatively large spreading in the group. The teachers noticed a clear difference regarding the questions asked and the discussions that took place when comparing the project with traditional lessons/lectures. Altogether, the project was found to have benefits from both motivation and learning perspectives.

  • 311.
    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.

  • 312.
    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)
  • 313.
    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.

  • 314.
    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)
    Download full text (pdf)
    fulltext
  • 315.
    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.

  • 316.
    Wren, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Renner, Johan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    THERMODYNAMICS OF MAN – A CDIO-APPROACH TO UNDERSTANDHUMAN PHYSIOLOGY FROM THE FIRST PRINCIPLE2013In: Proceedings of the 9th International CDIO Conference, Massachusetts Institute of Technology and Harvard UniversitySchool of Engineering and Applied Sciences, Cambridge, Massachusetts, June 9 – 13, 2013, 2013Conference paper (Refereed)
    Abstract [en]

    A multi-disciplinary CDIO project ranging from physiology to thermodynamics are used tointroduce first year engineering students to an engineering task, and to introduce generalengineering skills like project management, group dynamics, human interaction as well aswritten and oral presentations.

  • 317. Xiong, Changsheng
    et al.
    Sjöberg, Birgitta Janero
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Sveider, Per
    Linköping University, Department of Biomedical Engineering.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. 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.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Problems in timing of respiration with the nasal thermistor technique.1993In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 6, no 2, p. 210-216Article in journal (Refereed)
    Abstract [en]

    When one analyzes transvalvular and venous flow velocity patterns, it is important to relate them to respiration. For this reason a nasal thermistor technique is often used, although it is known that this signal is delayed in relation to intrathoracic pressure changes. The magnitude and variation in delay have not been investigated previously and were, therefore, studied in a model experiment in 10 normal subjects, in 10 patients with obstructive, and in 10 patients with restrictive pulmonary disease. Esophageal pressure variations measured with an air-filled balloon served as a gold standard for intrathoracic pressure changes. During basal conditions there was, for both patient groups and normal subjects, a considerable delay of the thermistor signal. The average delay for all subjects was 370 msec with a wide variation (from 120 to 720 msec). At higher breathing frequencies the delay shortened to 310 msec (P < 0.01) but there was still a wide variation (ranging from 200 to 470 msec). Theoretic calculations show that the delay caused by the respiratory system accounts for only a minor portion of the total delay. Model experiments confirmed that the response characteristics of the thermistor probes limit the accuracy in timing of respiration. The total delay with the investigated thermistor technique is too long and variable to fulfil clinical demands.

  • 318.
    Ziegler, Magnus
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Welander, Martin
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Lantz, Jonas
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Lindenberger, Marcus
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping.
    Bjarnegård, Niclas
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Länne, Toste
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Dyverfeldt, Petter
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Visualizing and quantifying flow stasis in abdominal aortic aneurysms in men using 4D flow MRI2019In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 57, p. 103-110Article in journal (Refereed)
    Abstract [en]

    Purpose: To examine methods for visualizing and quantifying flow stasis in abdominal aortic aneurysms (AAA) using 4D Flow MRI. Methods: Three methods were investigated: conventional volumetric residence time (VRT), mean velocity analysis (MVA), and particle travel distance analysis (TDA). First, ideal 4D Flow MRI data was generated using numerical simulations and used as a platform to explore the effects of noise and background phase-offset errors, both of which are common 4D Flow MRI artifacts. Error-free results were compared to noise or offset affected results using linear regression. Subsequently, 4D Flow MRI data for thirteen (13) subjects with AAA was acquired and used to compare the stasis quantification methods against conventional flow visualization. Results: VRT (R-2 = 0.69) was more sensitive to noise than MVA (R-2 = 0.98) and TDA (R-2 = 0.99) at typical noncontrast signal-to-noise ratio levels (SNR = 20). VRT (R-2 = 0.14) was more sensitive to background phase-offsets than MVA (R-2 = 0.99) and TDA (R-2 = 0.96) when considering a 95% effective background phase-offset correction. Qualitatively, TDA outperformed MVA (Wilcoxon p amp;lt; 0.005, mean score improvement 1.6/5), and had good agreement (median score 4/5) with flow visualizations. Conclusion: Flow stasis can be quantitatively assessed using 4D Flow MRI. While conventional residence time calculations fail due to error accumulation as a result of imperfect measured velocity fields, methods that do not require lengthy particle tracking perform better. MVA and TDA are less sensitive to measurement errors, and TDA generates results most similar to those obtained using conventional flow visualization.

    Download full text (pdf)
    fulltext
  • 319.
    Åstrand, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Physiology. Linköping University, Faculty of Health Sciences.
    Stålhand, Jonas
    Linköping University, Department of Management and Engineering, 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.
    Sonesson, B.
    Malmö University Hospital.
    Länne, Toste
    Linköping University, Department of Medical and Health Sciences, Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Thoracic and Vascular Surgery in Östergötland.
    Karlsson, J
    Linköping University, Department of Medical and Health Sciences, Physiology. Linköping University, Faculty of Health Sciences.
    In vivo estimation of the contribution of elastin and collagen on the mechanical properties in the abdominal aorta of man: effect of age and gender2011In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 110, no 1, p. 8750-8757Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of the aorta affect cardiac function and are related to cardiovascular morbidity/mortality. This study was designed to evaluate the isotropic (mainly elastin, elastiniso) and anisotropic (mainly collagen, collagenani) material parameters within the human aorta in vivo. Thirty healthy men and women in three different age categories (23–30, 41–54, and 67–72 yr) were included. A novel mechanical model was used to identify the mechanical properties and the strain field with aid of simultaneously recorded pressure and radius in the abdominal aorta. The magnitudes of the material parameters relating to both the stiffness of elastiniso and collagenani were in agreement with earlier in vitro studies. The load-bearing fraction attributed to collagenani oscillated from 10 to 30% between diastolic and systolic pressures during the cardiac cycle. With age, stiffness of elastiniso increased in men, despite the decrease in elastin content that has been found due to elastolysis. Furthermore, an increase in stiffness of collagenani at high physiological pressure was found. This might be due to increased glycation, as well as changed isoforms of collagen in the aortic wall with age. A marked sex difference was observed, with a much less age-related effect, both on elastiniso and collagenani stiffness in women. Possible factors of importance could be the effect of sex hormones, as well as differing collagen isoforms, between the sexes.

  • 320.
    Öberg, Sofia
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Metod för beräkning av andelen fossilt kol i avfallsbränsle2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    From 2013 waste-to-energy (WTE) plants in Sweden are included in the European Union Emissions Trading System, EU ETS. EU ETS involves only carbon emissions created by fossil fuels. Household waste and industrial waste, which is the fuel, consists of a mixture of biogenic and fossil fuels. This amendment imposes new demands on measurement accuracy and reporting of fossil part of carbon emissions. In the current situation there are a number of methods to carry out these measurements, but these methods are highly expensive. This work is carried out on behalf of Tekniska verken, Linköping, which owns and operates WTE plants and thus have strong interest in this result. The aim of this work is to investigate whether a new calculation method can be applied and if the method is reliable for the determination of fossil carbon in the emissions. When starting the work an equation for the heating value was available. This equation was the basis for the further calculation of the proportion of the fossil and biogenic fuels in the waste. The method was recommended to be based on the facility's existing operational data. To tackle the main problem, the work started with a review of the literature .To make the calculations, knowledge of the fuel heating value and the biogenic and fossil fuel heating value were needed. Due to these parameters the method was divided into six different areas and related equations, which are reported below. o Mass Balance / waste composition o Heat Value Calculation o Water Balance / moisture in fuel o Ash content o Effect relationships o Flue gas The calculation method published in this work might work theoretically, but for reliable results further studies in each area are required. The calculation method requires many measurement signals which makes the method become uncertain. Small changes in the measured signals provide a major impact on the method's final results, i.e the proportion of fossil carbon in the waste. This means that the method requires reliable measurement data with small uncertainties to produce a correct outcome. Before the implementation of the calculated method the recommendation is to verify the method with other known methods, such as 14C - analysis.

    Download full text (pdf)
    Metod för beräkning av andelen fossilt kol i avfallsbränsle
4567 301 - 320 of 320
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf