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| 2. |
- Forsberg, Daniel, et al.
(författare)
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Fully automatic measurements of axial vertebral rotation for assessment of spinal deformity in idiopathic scoliosis
- 2013
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 58:6, s. 1775-1787
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Tidskriftsartikel (refereegranskat)abstract
- Reliable measurements of spinal deformities in idiopathic scoliosis are vital, since they are used for assessing the degree of scoliosis, deciding upon treatment and monitoring the progression of the disease. However, commonly used two dimensional methods (e.g. the Cobb angle) do not fully capture the three dimensional deformity at hand in scoliosis, of which axial vertebral rotation (AVR) is considered to be of great importance. There are manual methods for measuring the AVR, but they are often time-consuming and related with a high intra- and inter-observer variability. In this paper, we present a fully automatic method for estimating the AVR in images from computed tomography. The proposed method is evaluated on four scoliotic patients with 17 vertebrae each and compared with manual measurements performed by three observers using the standard method by Aaro-Dahlborn. The comparison shows that the difference in measured AVR between automatic and manual measurements are on the same level as the inter-observer difference. This is further supported by a high intraclass correlation coefficient (0.971-0.979), obtained when comparing the automatic measurements with the manual measurements of each observer. Hence, the provided results and the computational performance, only requiring approximately 10 to 15Â s for processing an entire volume, demonstrate the potential clinical value of the proposed method.
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| 3. |
- Lundström, Ludvig, et al.
(författare)
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Influence on the stability of generator rotors due to radial and tangential magnetic pull force
- 2007
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Ingår i: IET Electric Power Applications. - : Institution of Engineering and Technology (IET). - 1751-8660 .- 1751-8679. ; 1:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Forces due to nonuniform airgaps in rotating electrical machines have been a researchtopic for over 100 years. However, most research in the area of rotating electrical machines hasbeen performed on motors. Large forces in hydropower generators can lead to expensive damageand failures. Therefore, it is of interest to calculate the forces that arise in a large synchronousgenerator with an eccentric rotor and study the influence these forces have on the stability of thegenerator rotor. A 74 MVA synchronous hydropower generator was simulated with an eccentricrotor, using a time-stepping finite-element technique. The forces were calculated using Coulomb’svirtual-work method and simulations were performed for no-load and load cases. The resultingforce was found to be reduced significantly when a damper winding was taken into account. Aninteresting effect of the rotor damper winding was that it reduced the eccentricity force andintroduced a force component perpendicular to the direction of eccentricity. The results from thefinite-element simulations were used to determine how the forces affect the stability of the generatorrotor. Damped natural eigenfrequencies and damping ratio for load and no-load conditions arepresented. When applying the forces computed in the time-dependent model, the damped naturaleigenfrequencies were found to increase and the stability of the generator rotor was found to bereduced compared with when the forces were computed in a stationary model.
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| 4. |
- Paloranta, Jimmie, et al.
(författare)
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Interaction with a large sized augmented string instrument intended for a public setting
- 2016
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Ingår i: Sound and Music Computing 2016. - Hamburg : Zentrum für Mikrotonale Musik und Multimediale Komposition (ZM4). - 9783000537004 ; , s. 388-395
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a study of the interaction with a large sized string instrument intended for a large installation in a museum, with focus on encouraging creativity,learning, and providing engaging user experiences. In the study, nine participants were video recorded while interacting with the string on their own, followed by an interview focusing on their experiences, creativity, and the functionality of the string. In line with previous research, our results highlight the importance of designing for different levels of engagement (exploration, experimentation, challenge). However, results additionally show that these levels need to consider the users age and musical background as these profoundly affect the way the user plays with and experiences the string.
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| 5. |
- Sidenmark, Ludvig, et al.
(författare)
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Gaze Behaviour on Interacted Objects during Hand Interaction in Virtual Reality for Eye Tracking Re-calibration
- 2019
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Ingår i: Eye Tracking Research and Applications Symposium (ETRA). - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450367097
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the probability and timing of attaining gaze fxations on interacted objects during hand interaction in virtual reality, with the main purpose for implicit and continuous eye tracking re-calibration. We conducted an evaluation with 15 participants in which their gaze was recorded while interacting with virtual objects. The data was analysed to fnd factors infuenc-ing the probability of fxations at diferent phases of interaction for diferent object types. The results indicate that 1) interacting with stationary objects may be favourable in attaining fxations to moving objects, 2) prolonged and precision-demanding interactions positively infuences the probability to attain fxations, 3) performing multiple interactions simultaneously can negatively impact the probability of fxations, and 4) feedback can initiate and end fxations on objects.
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| 6. |
- Tiensuu, Kiira, et al.
(författare)
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RAVEN: a student rocket program at Luleå University of Technology, Sweden
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72nd International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- RAVEN, Rocketry and Aerospace Vehicle Engineering in Norrbotten, is the first rocket project at Luleå University of Technology (LTU), Sweden. The project started in early 2020, and it aims to design, build, test and launch a hybrid propulsion rocket. The initial objectives are to reach an altitude of 10 km with an accompanying payload of 10 kg. The RAVEN team is based at the Kiruna Space Campus and consists of approximately 30 graduate students. The main goal of the first RAVEN rocket is to demonstrate its technology. The team is designing the entire rocket from scratch, including the hybrid propulsion system that uses nitrous oxide as the oxidising agent and paraffin as the solid fuel component, to produce approximately 6 kN of thrust. A modular rocket structure will offer customisation, enabling simple design changes in future iterations. Thus, the layout allows individual subsystems to be re-designed without changes directly affecting others. The project is meant to create a foundation for future student and research rocket projects at LTU. The follow-up developments could further iterate on the first rocket design, increasing hands-on education and providing more collaboration opportunities between the university and the aerospace industry – and eventually provide an in-house platform for research and education at the university or even for commercial start-ups. The infrastructure and resources, such as the proximity to the Esrange Space Center launch facility and support from the university and industry, make Northern Sweden an ideal location to establish a continuous rocket program.
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| 7. |
- Ödalen, Jörgen, 1975-
(författare)
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Rolling Out the Map of Justice
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traditionally, the promotion of socio-economic justice has been seen as an exclusive concern for the state and its citizens. Many contemporary political thinkers criticize this view and argue that the principles of justice which apply within a state also apply to the global level. Further, they often argue that this conclusion is strengthened by the increased level of interconnectedness between people and states created by globalization. It is said that even if principles of justice are constrained by institutional boundaries, these boundaries no longer coincide with state borders but rather extend transnationally, or even globally. In this thesis it is argued that the impacts on justice inferred from globalization are often seriously overstated. The demand for socio-economic justice is created exclusively by a special relationship between citizens. This relationship is constituted by a common membership in the kind of coercive institutional structure epitomized by the state. Under current state of affairs, state coercion has no counterpart in the global arena. The conclusion is that concerns of socio-economic justice should be reserved for the domestic arena. Yet, it is also argued that justice is pluralistic and other kinds of concern are applicable on a global scale. Issues of fairness in international trade are discussed as examples of such concerns, and it is concluded that the international trade regime should institutionalize a number of safeguards that reduce the vulnerability of developing states.
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