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- Fahlström, Karl
(author)
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Laser welding of boron steels for light-weight vehicle applications
- 2015
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Licentiate thesis (other academic/artistic)abstract
- Laser beam welding has gained a significant interest during the last two decades. The suitability of the process for high volume production has the possibility to give a strong advantage compared to several other welding methods. However, it is important to have the process in full control since various quality issues may otherwise occur. During laser welding of boron steels quality issues such as imperfections, changes in local and global geometry as well as strength reduction can occur. The aspects that need to be considered are strongly depending on alloy content, process parameters etc. These problems that can occur could be fatal for the construction and the lowest level of occurrence is wanted, independent of industry.The focus of this study has been to investigate the properties of laser welded boron steel. The study includes laser welding of boron alloyed steels with strengths of 1500 MPa and a recently introduced 1900 MPa grade. Focus has been to investigate weldability and the occurrence of cracks, porosity and strength reducing microstructure that can occur during laser welding, as well as distortion studies for tolerances in geometry. The results show that both conventional and 1900 MPa boron alloyed steel are suitable for laser welding.Due to the martensitic structure of welds the material tends to behave brittle. Cracking and porosity do not seem to be an issue limiting the use of these steels. For tolerances in geometry for larger structures tests has been done simulating laser welding of A-pillars and B-pillars. Measurements have been done with Vernier caliper as well as a more advanced optical method capturing the movements during the welding sequence. Results from the tests done on Ushaped beams indicates that depending on the geometry of the structure and heat input distortions can be controlled to give distortions from 1 to 8 mm, at a welding length of 700 mm. This means that important geometry points can be distorted several millimeters if the laser welding process not is controlled.
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| 2. |
- Nord, Anette, 1972-
(author)
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Bystander CPR : New aspects of CPR training among students and the importance of bystander education level on survival
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Background: It has been proved that bystander cardiopulmonary resuscitation (CPR) saves lives; however, which training method in CPR is most instructive and whether survival is affected by the training level of the bystander have not yet been fully described. Aim: To identify the factors that may affect 7th grade students’ acquisition of CPR skills during CPR training and their willingness to act, and to describe 30-day survival from outof- hospital cardiac arrest (OHCA) after bystander CPR and the actions performed by laymen versus off-duty medically educated personnel. Methods: Studies I–III investigate a CPR training intervention given to students in 7th grade during 2013–2014. The classes were randomized to the main intervention: the mobile phone application (app) or DVD-based training. Some of the classes were randomized to one or several additional interventions: a practical test with feedback, reflection, a web course, a visit from elite athletes and automated external defibrillator (AED) training. The students’ practical skills, willingness to act and knowledge of stroke symptoms, symptoms of acute myocardial infarction (AMI) and lifestyle factors were assessed directly after training and at 6 months using the Laerdal PC SkillReporting system (and entered into a modified version of the Cardiff test scoring sheet) and a questionnaire. The Cardiff test resulted in a total score of 12–48 points, and the questionnaire resulted in a total score of 0–7 points for stroke symptoms, 0–9 points for symptoms of AMI and 0– 6 points on lifestyle factors. Study IV is based on retrospective data from the national quality register, the Swedish registry of cardiopulmonary resuscitation, 2010-2014. Results: A total of 1339 students were included in the CPR training intervention. The DVD-based group was superior to the app-based group in CPR skills, with a total score of 35 (SD 4.o) vs 33 (SD 4.2) points directly after training (p<0.001) and 33 (SD 4.0) vs 31 (SD 4.2) points at six months (p<0.001). Of the additional interventions, the practical test with feedback had the greatest influence regarding practical skills: at six months the intervention group scored 32 (SD 3.9) points and the control group (CPR only) scored 30 (SD 4.0) points (p<0.001). Reflection, the web course, visits from elite athletes and AED training did not further increase the students’ acquisition of practical CPR skills.The students who completed the web course Help-Brain-Heart received a higher total score for theoretical knowledge in comparison with the control group, directly after training: stroke 3.8 (SD 1.8) vs 2.7 (SD 2.0) points (p<0.001); AMI 4.0 (SD 2.0) vs 2.5 (SD 2.0) points (p<0.001); lifestyle factors 5.4 (SD 1.2) vs 4.5 (SD 2.0) points p<0.001.Most of the students (77% at 6 months), regardless of the intervention applied, expressed that they would perform both chest compressions and ventilations in a cardiac arrest (CA) situation involving a relative. If a stranger had CA, a significantly lower proportion of students (32%; p<0.001) would perform both compressions and ventilations. In this case, however, many would perform compressions only.In most cases of bystander-witnessed OHCA, CPR was performed by laymen. Off-duty health care personnel bystanders initiated CPR within 1 minute vs 2 minutes for laymen (p<0.0001). Thirty-day survival was 14.7% among patients who received CPR from laymen and 17.2% (p=0.02) among patients who received bystander CPR from off-duty health care personnel. Conclusions: The DVD-based method was superior to the app-based method in terms of teaching practical CPR skills to 7th grade students. Of the additional interventions, a practical test with feedback was the most efficient intervention to increase learning outcome. The additional interventions, reflection, web course, visit from elite athletes and AED did not increase CPR skills further. However, the web course Help-Brain-Heart improved the students’ acquisition of theoretical knowledge regarding stroke, AMI and lifestyle factors. For OHCA, off-duty health care personnel bystanders initiated CPR earlier and 30-day survival was higher compared with laymen bystanders.
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| 3. |
- Svensson, Leif, 1981-
(author)
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A Theology for the Bildungsbürgertum : Ritschl in Context
- 2018
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Doctoral thesis (other academic/artistic)abstract
- The subject of this historical-theological investigation is the German Lutheran theologian Albrecht Ritschl (1822-1889). Ritschl’s theology is understood in the context of the de-Christianization of the German Bildungsbürgertum (educated middle class). It is demonstrated that an ambition to counteract this tendency runs all through Ritschl’s theological thinking. More specifically, the study argues that Ritschl’s theology can be seen as a response to three intellectual challenges to Christianity in general and Lutheranism in particular – historical criticism, materialism, and anti-Lutheran polemics.Part I concentrates on historical criticism and Ritschl’s interpretation of history. Chapter 1, which presents Leopold von Ranke’s historicist-oriented historical school at the University of Berlin and Ferdinand Christian Baur’s theological Tübingen school, provides the wider setting of Ritschl’s historical analysis. It is argued, in chapter 2, that those schools had a significant impact – albeit in different ways – on Ritschl’s understanding of history. The contribution of Ritschl to the so-called first quest for the historical Jesus is analyzed in chapter 3, which also points out that Johannes Weiss’ and Albert Schweitzer’s apocalyptic critique of the first quest undermined the historical foundation of Ritschl’s theology.In part II, the focus is on materialism and the metaphysical framework of Ritschl’s theology. Chapter 4 discusses anthropological materialism, scientific materialism, and late idealism – three intellectual movements of relevance to Ritschl’s metaphysics. In chapter 5, Ritschl’s metaphysical framework is described as an attempt to safeguard the spiritual dimension of existence against the threat of materialism. This chapter also argues that Ritschl’s metaphysics is indebted to Hermann Lotze’s late idealist philosophy. Chapter 6 highlights the relationship between Ritschl’s metaphysics and his protest against “classical metaphysical theology,” and examines how Ritschl’s metaphysical framework leads him to reject natural theology and the classical Christological and trinitarian dogmas.Part III discusses Ritschl’s theological ethics or understanding of Christian life in the context of the values of the Bildungsbürgertum and against the background of anti-Lutheran polemics. In chapter 7, an overview of the ethos of the educated middle class is provided. The subject of chapter 8 is Ritschl’s defense of Luther’s cultural importance against Paul de Lagarde’s criticism of the Lutheran Reformation. Chapter 9 carries out an analysis of Ritschl’s thinking on Christian life and its modern sources, especially noting the influences of Immanuel Kant and Friedrich Schleiermacher, and exploring the similarities between Ritschl’s ethics and the values of the educated middle class.In the Conclusion, the findings of the investigation are summarized in the claim that Ritschl’s responses to historical criticism, materialism, and anti-Lutheran polemics demonstrate that his theology in many respects was a theology for the Bildungsbürgertum. The concluding chapter also reflects on the implications of the present study for the common characterization of Ritschl as a Kulturprotestant (mediator between the Protestant Reformation and modern culture), problematizes Ritschl’s interpretation of the historical Jesus, and argues that Ritschl’s theological project was essentially abandoned by his most famous students.
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| 4. |
- Svensson, Daniel, 1983-
(author)
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Scientizing performance in endurance sports : The emergence of ‘rational training’ in cross-country skiing, 1930-1980
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Elite athletes of today use specialized, scientific training methods and the increasing role of science in sports is undeniable. Scientific methods and equipment has even found its way into the practice of everyday exercisers, a testament to the impact of sport science. From the experiential, personal training regimes of the first half of the 20th century to the scientific training theories of the 1970s, the ideas about training and the athletic body shifted.The rationalization process started in endurance sports in the 1940s. It was part of a struggle between two models of training; natural training and rational training. Physiologists wanted to rid training of individual and local variations and create a universal model of rational, scientific training. The rationalization of training and training landscapes is here understood as an aspect of sportification, a theory commonly used to describe similar developments in sports where increasing regimentation, specialization and rationalization are among the main criteria. This dissertation adds the concept of technologies of sportification to explain the role that micro-technologies and practices (such as training logs, training camps and scientific tests) have in the scientization of training.This thesis thus sets out to analyze the role that science has played in training during the 20th century. It is a history about the rationalization of training, but also about larger issues regarding the role of personal, experiential knowledge and scientific knowledge. The main conclusions are that the process of scientization never managed to rid training of components from natural, experiential training, and that the effort by Swedish physiologists to introduce rational training was part of the larger rationalization movement at the time. In the end, training knowledge was a co-production between practitioners and theoreticians, skiers and scientists.
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