| 1. |
- Andersson, Anders, 1957-
(författare)
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Numerical Conformal Mappings for Waveguides
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acoustic or electro-magnetic scattering in a waveguide with varying direction and cross-section can be re-formulated as a two-dimensional scattering problem, provided that the variations take place in only one dimension at a time. By using the so-called Building Block Method, it is possible to construct the scattering properties of a combination of scatterers when the properties of each scatterer are known. Hence, variations in the waveguide geometry or in the boundary conditions can be treated one at a time. Using the Building Block Method, the problem takes the form of the Helmholtz equation for stationary waves in a waveguide of infinite length and with smoothly varying geometry and boundary conditions. A conformal mapping is used to transform the problem into a corresponding problem in a straight horizontal waveguide, and by expanding the field in Fourier trigonometric series, the problem can be reformulated as an infinite-dimensional ordinary differential equation. From this, numerically solvable differential equations for the reflection and transmission operators are derived. To be applicable in the Building Block Method, the numerical conformal mapping must be constructed such that the direction of the boundary curve can be controlled. At the channel ends ,it is an indispensable requirement, that the two boundary curves are (at least) asymptotically parallel and straight. Furthermore, to achieve bounded operators in the differential equations, the boundary curves must satisfy different regularity conditions, depending on the boundary conditions. In this work, several methods to accomplish such conformal mappings are presented. The Schwarz–Christoffel mapping, which is a natural starting point and for which also efficient numerical software exists, can be modified in different ways in order to achieve polygons with rounded corners. We present algorithms by which the parameters in the mappings can be determined after such modifications. We show also how the unmodified Schwarz–Christoffel mapping can be used for regions with a smooth boundary. This is done by constructing an appropriate outer polygon to the considered region.Finally, we introduce one method that is not Schwarz–Christoffel-related, by showing how one of the so-called zipper algorithms can be used for waveguides. Keywords: waveguides, building block method, numerical conformalmappings, Schwarz–Christoffel mapping, rounded corners method, approximate curve factors, outer polygon method, boundary curvature, zipper method, geodesic algorithm, acoustic wave scattering, electro-magnetic wave scattering
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| 2. |
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| 3. |
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| 4. |
- Nilsson, Monica, et al.
(författare)
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Spiders, firesouls, and little fingers : Necessary magic in university–community collaboration
- 2004
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Ingår i: Anthropology & Education Quarterly. - Berkeley : American Anthropological Association. - 0161-7761 .- 1548-1492. ; 35:3
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Tidskriftsartikel (refereegranskat)abstract
- Based on extensive research on university-community collaborative education projects in southern California and southern Sweden, this article proposes two roles and a research strategy/approach as elements essential to sustained collaboration. Recognition and fulfillment of the roles of “spider” and “firesoul,” while “leading with the little finger,” contribute to educational anthropology by linking qualitative/ethnographic research with university and community learning, practice, and service in a process of involvement
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| 5. |
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| 6. |
- Nilsson, Örjan, et al.
(författare)
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Fysik med Excel
- 1999
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Bok (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Oliva, Delmy, 1967-, et al.
(författare)
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Individual genetic variation might predict acute skin reactions in women undergoing adjuvant breast cancer radiotherapy
- 2018
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Ingår i: Anticancer Research. - : International Institute of Anticancer Research. - 0250-7005 .- 1791-7530. ; 38:12, s. 6763-6770
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Tidskriftsartikel (refereegranskat)abstract
- Adverse skin reactions during radiotherapy (RT) are common. The aim of this study was to explore whether genetic variation might be linked to acute radiation skin reactions (ARSR). Materials and Methods: One hundred and nineteen women undergoing adjuvant RT for breast cancer were included. The symptoms of itching, burning and irritation were self-reported twice using the visual analogue scale. Assessments used the Radiation Therapy Oncology Group scoring system for acute RT skin reaction (RTOG scale). Blood-based single nucleotide polymorphism (SNP) analysis was performed. Thirty SNPs of well-defined functional genes were investigated. Results: All women were assessed with ARSR. After RT, the women self-reported itching (n=97), burning (n=64) and irritation (n=96). Two SNPs in X-Ray Repair Cross Complementing 2 gene (XRCC2) rs2040639 and interferon gamma (IFNG) rs2069705 genes were found to be associated with ARSR. Conclusion: An association between two SNPs and ARSR was found. The possibility of using these SNPs as prognostic biomarkers for ARSR as tools to improve the care of patients needs further investigation.
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| 9. |
- Österlund, Michael, et al.
(författare)
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Projectile Motion in Real Life
- 2000
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Ingår i: Proc. Physics Teaching in Engineering Education (PTEE 2000).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Österlund, Michael, et al.
(författare)
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Simulering med Interactive Physics
- 1997
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Ingår i: Datorn i Utbildningen. - 1100-3650. ; :1, s. 36-39
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Tidskriftsartikel (populärvet., debatt m.m.)
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