| 11. |
- Jansson, Johan, et al.
(författare)
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A discrete mechanics model for deformable bodies
- 2002
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Ingår i: Computer-Aided Design. - 0010-4485 .- 1879-2685. ; 34:12, s. 913-928
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the theory and implications of a discrete mechanics model for deformable bodies, incorporating behavior such as motion, collision, deformation, etc. The model is fundamentally based on inter-atomic interaction, and recursively reduces resolution by approximating collections of many high-resolution elements with fewer lower-resolution elements. The model can be viewed as an extended mass-spring model. We begin by examining the domain of conceptual design, and find there is a need for physics based simulation, both for interactive shape modeling and analysis. We then proceed with describing a theoretical base for our model, as well as pragmatic additions. Applications in both interactive physics based shape modeling and analysis are presented. The model is aimed at conceptual mechanical design, rapid prototyping, or similar areas where adherence to physical principles, generality and simplicity are more important than metric correctness.
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| 12. |
- Jansson, Johan, et al.
(författare)
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Combining deformable- and rigid-body mechanics simulation
- 2003
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Ingår i: The Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315. ; 19:5, s. 280-290
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Tidskriftsartikel (refereegranskat)abstract
- We present an interface between a deformable-body mechanics model and a rigid-body mechanics model. What is novel with our approach is that the physical representation in both the models is the same, which ensures behavioral correctness and allows great flexibility. We use a mass-spring representation extended with the concept of volume, and thus contact and collision. All physical interaction occurs between the mass elements only; thus there is no need for the explicit handling of interaction between rigid and deformable bodies or between rigid and rigid bodies. This also means that bodies can be partially rigid and partially deformable. It is also possible to change dynamically whether part of a body should be rigid or not. We present a demonstration example and possible applications in conceptual design engineering, geometric modeling, as well as computer animation.
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| 13. |
- Jansson, Johan, et al.
(författare)
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Model based control and optimization in pulpindustry
- 2004
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Ingår i: Proceedings of SIMS 2004. - 8774753169 ; , s. 103-110
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a combination of the usage of a model for the whole mill on-line simulation and more advanced models for specific process sections for control systems and online diagnostics. Different solution methods are described together with where the different approaches are best suited.
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| 14. |
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| 15. |
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| 16. |
- Jansson, Johan
(författare)
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The Formation of Hidden Information : The Geography of the Swedish Internet Industry
- 2004
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Taking off from the burst of the Internet bubble and the ideas of the new technology as a space shrinking development this paper deals with the Internet industry in Stockholm, Sweden, and the question of agglomeration of economic of activities. Through a theoretical framework of localized and tacit knowledge, this paper discusses the importance of proximity, especially in the sense of knowledge transmission. The paper is structured in three main sections. First, a discussion of the benefits of being located in an agglomeration of firms is introduced, and connected to this some important ideas coming out of the literature on localized learning and tacit knowledge are being reviewed. Second, to give a short introduction to the Swedish Internet industry and the agglomeration of Internet firms in Stockholm. Finally, the paper will analyse empirical findings from a interview survey in the Stockholm Internet agglomeration from such a theoretical framework. The empirical findings suggests that firms within the Internet industry are located in close proximity to each other because of the importance of dense informal interpersonal networks, that facilitate the search for both new customers and collaborators. The findings also stress the importance of proximity in creating these dense networks.
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| 17. |
- Jansson, Patrik, 1972, et al.
(författare)
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A Framework for Polytypic Programming on Terms, with an Application to Rewriting
- 2000
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Ingår i: Workshop on Generic Programming.
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Konferensbidrag (refereegranskat)abstract
- Rewriting is a typical example of a polytypic function. Given any value of a datatype (an algebra of terms), and rules to rewrite values of that datatype, we want a function that rewrites the value to normal form if the value is normalizable. This paper develops a polytypic rewriting function that uses the parallel innermost rewriting strategy. It improves upon our earlier work on polytypic rewriting in two fundamental ways. Firstly, the rewriting function uses a term interface that hides the polytypic part from the rest of the program. The term interface is a framework for polytypic programming on terms. This implies that the rewriting function is independent of the particular implementation of polytypism. We give several functions and laws on terms, which simplify calculating with programs. Secondly, the rewriting function is developed together with a correctness proof. We just present the result of the correctness proof, the proof itself is published elsewhere.
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| 18. |
- Jansson, Patrik, 1972, et al.
(författare)
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Polytypic Data Conversion Programs
- 2002
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Ingår i: Science of Computer Programming. - 0167-6423. ; 43:1, s. 35-75
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Tidskriftsartikel (refereegranskat)abstract
- Several generic programs for converting values from regular datatypes to some other format, together with their corresponding inverses, are constructed. Among the formats considered are shape plus contents, compact bit streams and pretty printed strings. The different data conversion programs are constructed using John Hughes arrow combinators along with a proof that printing (from a regular datatype to another format) followed by parsing (from that format back to the regular datatype) is the identity. The printers and parsers are described in PolyP, a polytypic extension of the functional language Haskell.
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| 19. |
- Malmstrom, Vivianne, et al.
(författare)
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T cells that are naturally tolerant to cartilage-derived type II collagen are involved in the development of collagen-induced arthritis
- 2000
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Ingår i: Arthritis Research. - : Springer Science and Business Media LLC. - 1465-9905. ; 2:4, s. 315-326
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Tidskriftsartikel (refereegranskat)abstract
- The immunodominant T-cell epitope that is involved in collagen-induced arthritis (CIA) is the glycosylated type II collagen (CII) peptide 256-270. In CII transgenic mice, which express the immunodominant CII 256-270 epitope in cartilage, the CII-specific T cells are characterized by a partially tolerant state with low proliferative activity in vitro, but with maintained effector functions, such as IFN-gamma secretion and ability to provide B cell help. These mice were still susceptible to CIA. The response was mainly directed to the glycosylated form of the CII 256-270 peptide, rather than to the nonglycosylated peptide. Tolerance induction was rapid; transferred T cells encountered CII within a few days. CII immunization several weeks after thymectomy of the mice did not change their susceptibility to arthritis or the induction of partial T-cell tolerance, excluding a role for recent thymic emigrants. Thus, partially tolerant CII autoreactive T cells are maintained and are crucial for the development of CIA.
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| 20. |
- Nilsson, B, et al.
(författare)
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Effects of preoperative parathyroid localisation studies on the cost of operations for persistent hyperparathyroidism.
- 2001
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Ingår i: The European journal of surgery = Acta chirurgica. - : Oxford University Press (OUP). - 1102-4151. ; 167:8, s. 587-91
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Tidskriftsartikel (refereegranskat)abstract
- To find out whether preoperative parathyroid localisation studies are cost-effective in patients with persistent hyperparathyroidism (HPT).Retrospective study.University hospital, Sweden.29 consecutive patients with persistent HPT who were reoperated on with or without localisation studies. 15 other patients had initial operations for HPT without localisation studies.Initial or repeat operation for HPT, localisation studies with 99mTc sestamibi scintigraphy, and catheterisation of large cervical and mediastinal veins with measurements of serum concentrations of parathyroid hormone.Operative time. Cost of operations, frozen section biopsy and localisation studies.The mean durations of reoperation with localisation studies and for the initial operation without them, were 124 and 135 minutes, respectively, while it was 269 minutes for reoperation without studies. For patients who had localisation studies the mean total cost of the investigations, operating time, and frozen section biopsy was 28% less than for patients who were reoperated on without such studies.Preoperative localisation studies before repeat operations for HPT were cost-effective. Even if it has not been shown in this series, the reduction in operating time and the extent of dissection by localisation studies has the potential to decrease morbidity.
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