| 11. |
- Engström, Tomas, 1950, et al.
(författare)
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Utvärdering av kundanpassad arbetstid vid Volvo Lastvagnar i Tuve
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report (“avnämarrapport” in Swedish) for the company in question which is financed by a research foundation. It is a questionnaire survey, in this case, a so-called total survey of all blue-collar employees. This was beginning of a long-term cooperation with the Swedish Metal Workers Union (Metal in Swedish) concerning among other things questionnaire surveys.
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| 12. |
- Fredenberg, Erik, 1979-
(författare)
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Spectral Mammography with X-Ray Optics and a Photon-Counting Detector
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Early detection is vital to successfully treating breast cancer, and mammography screening is the most efficient and wide-spread method to reach this goal. Imaging low-contrast targets, while minimizing the radiation exposure to a large population is, however, a major challenge. Optimizing the image quality per unit radiation dose is therefore essential. In this thesis, two optimization schemes with respect to x-ray photon energy have been investigated: filtering the incident spectrum with refractive x-ray optics (spectral shaping), and utilizing the transmitted spectrum with energy-resolved photon-counting detectors (spectral imaging). Two types of x-ray lenses were experimentally characterized, and modeled using ray tracing, field propagation, and geometrical optics. Spectral shaping reduced dose approximately 20% compared to an absorption-filtered reference system with the same signal-to-noise ratio, scan time, and spatial resolution. In addition, a focusing pre-object collimator based on the same type of optics reduced divergence of the radiation and improved photon economy by about 50%. A photon-counting silicon detector was investigated in terms of energy resolution and its feasibility for spectral imaging. Contrast-enhanced tumor imaging with a system based on the detector was characterized and optimized with a model that took anatomical noise into account. Improvement in an ideal-observer detectability index by a factor of 2 to 8 over that obtained by conventional absorption imaging was found for different levels of anatomical noise and breast density. Increased conspicuity was confirmed by experiment. Further, the model was extended to include imaging of unenhanced lesions. Detectability of microcalcifications increased no more than a few percent, whereas the ability to detect large tumors might improve on the order of 50% despite the low attenuation difference between glandular and cancerous tissue. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.
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| 13. |
- Frei, R., et al.
(författare)
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Evolvable assembly systems : Towards user friendly manufacturing
- 2007
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Ingår i: ISAM 2007 - IEEE International Symposium on Assembly and Manufacturing. - : IEEE. - 1424405637 - 9781424405633 ; , s. 288-293
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Konferensbidrag (refereegranskat)abstract
- Besides coping with the highly dynamic product and production system life cycles with ever-changing requirements, modern assembly systems also need to be user-friendly. Their modularity at fine granularity-level combined with local intelligence and a distributed control approach allows the systems to evolve together with the requirements - but their complexity would soon not be manageable from outside any more if user-friendliness was not considered a major criterion. Systems must be made to serve their users. Thanks to Self-* capabilities, systems can gain an increasingly high degree of autonomy. Diagnosis plays a particularly important role in this process.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Insulander Björk, Klara L, 1982, et al.
(författare)
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Comparison of thorium-based fuels with different fissile components in existing boiling water reactors
- 2009
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Ingår i: Proc. Int. Congress on Advances in Nuclear Power Plants (ICAPP '09). ; 3, s. 1982-1987
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Konferensbidrag (refereegranskat)abstract
- Three different types of thorium based BWR fuel have been developed, in each of which thorium was combined with a different fissile component, the three components being reactor grade plutonium, uranium enriched to 20% in uranium 235 and pure uranium 233. A BWR nuclear bundle design, based on the geometrical fuel assembly design GE14, was developed for each of these fissile components. The properties and performance of the corresponding fuel assemblies were investigated via full core calculations carried out for an existing BWR and compared with the ones of an ordinary Low Enriched Uranium (LEU) fuel, which was developed for reference. The fuel assemblies and cores were designed to meet existing fuel design criteria, and were then analyzed with regards to reactivity coefficients, delayed neutron fractions, control rod worths and shutdown margins. The results show that all three alternatives seem to be feasible, although some difficulties remain with complying with the thermal limits, and with the moderator temperature and coolant void coefficients of the U-233 containing fuel being positive under some circumstances.
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| 18. |
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| 19. |
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| 20. |
- Kitamura, Yasunori, et al.
(författare)
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Calculation of higher moments of the neutron multiplication process in a time-varying medium
- 2007
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 34:5, s. 385-395
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Tidskriftsartikel (refereegranskat)abstract
- The zero-power reactor noise theory in a steady neutron multiplying medium was extended recently to a medium randomly varying in time to bridge the fields of the zero-power and the power reactor noise. For a time-varying medium in which the transition probability randomly fluctuates, only the use of the probability generating function technique based on the forward master equation approach is practical. However, with the forward master equation approach, the treatment of the joint moments of the neutron number and the medium state leads to a closure problem. Recently, the capability of the moment calculation technique for such cases was extended such that the closure problem could be solved exactly. The present paper describes and demonstrates this closure-free moment calculation technique in a time-varying binary multiplying medium, in which the medium state has two possible realizations. In addition to the first two moments of the neutron number N alone (irrespective of the medium state η), the joint moments of Nn and ηm, i.e., , were also obtained in a compact form for n = 1, 2 and arbitrary values of m, without a closure assumption. It was found that, for even m values, the asymptotic values of Nn and ηm are uncorrelated, whereas, for odd m values, they are negatively correlated, namely, their covariance is less than zero. The first two moments of the neutron number theoretically obtained were verified by the Monte Carlo technique. A perfect agreement was found between the Monte Carlo and the theoretical solutions. The closure-free moment calculation technique demonstrated in the present paper is expected to be applicable to various other problems related to the birth-and-death process with fluctuations of the transition probability, in which a closure problem occurs.
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