| 1. |
- Forsman, Åsa, 1972-, et al.
(författare)
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Generic structures of decision support systems for evaluation of policy measures to reduce catchment-scale nitrogen fluxes
- 2003
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Ingår i: Physics and Chemistry of the Earth. - 1474-7065 .- 1873-5193. ; 28:14-15, s. 589-598
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Tidskriftsartikel (refereegranskat)abstract
- Decision support systems (DSSs) for evaluation of different policy measures have two important functions: To assess how considered policy measures may influence the behavior of actors, and to predict the effects of a given set of actions generated from the anticipated behavior. So far, almost all attempts to construct DSSs for environmental management have focused on assessing the impact of a set of actions on the environment. Here, we describe the generic structure of a DSS that enables more complete evaluation of regional or national policies to reduce nitrogen inputs to water. In particular, we expound the principles for linking models of farm economic behavior to catchment-scale models of the transport and transformation of nitrogen in soil and water. First, we define system boundaries for nitrogen fluxes through the agricultural sector and the ambient environment to create a basis for model integration. Thereafter, we show how different modules operating on different temporal and spatial scales can be interlinked. Finally, we demonstrate how statistical emulators or meta-models can be derived to reduce the computational burden and increase the transparency of the DSS. In particular, we show when and how the temporal or spatial resolution of model inputs can be reduced without significantly influencing the estimates of annual nitrogen fluxes on a catchment scale.
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| 2. |
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| 3. |
- Gibmeier, Jens, et al.
(författare)
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Residual Stress Distributions around Clinched Joints
- 2002
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 404-407, s. 617-622
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Tidskriftsartikel (refereegranskat)abstract
- Clinching is a mechanical press joining method, which has become of growing interest in recent time since it has the potential to replace other conventional joining methods like e.g. spot welding. However, there still exists a lack of knowledge in terms of the mechanical behavior of clinched joints under quasistatic or cyclic loading. For that reason clinching is usually used for applications in structures which are not subjected to external loads. In particular the residual stress distribution in the vicinity of clinched joints and its influence on the mechanical behavior of the joints is unknown. Here diffraction methods are used for the determination of characteristic residual stress distributions in undismantled clinched samples. A combined residual stress determination by X-ray and neutron diffraction has been used to get a well-founded assessment of the residual stress distributions in the immediate vicinity of clinched joints. The residual stress analysis is supplemented by characterizations of the microstructures and the mechanical properties of single clinched joints. Two materials with different strain hardening behavior were used for clinching, a micro alloyed steel (ZStE340) and a non age hardenable aluminum base alloy (AlMg5). In addition two different common clinching techniques were applied - the TOX- [5] and the Eckold-technique [6]. Characteristic residual stress distributions were found for the combinations of clinching techniques and joined sheet materials investigated here. It has been determined that the clinching process induces predominantly compressive residual stresses inside the clinch and in the immediate vicinity of the clinch. The near surface residual stress distributions determined by X-ray diffraction measurements tend to reveal somewhat different residual stresses than measured by neutron diffraction, indicating a possible stress gradient through the sheet thickness. Further evaluation of the FWHM-values of the respective interference profiles shows that for both clinching techniques the largest amount of plastic deformation occurs in the clinch lock region.
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| 4. |
- Gibmeier, Jens, et al.
(författare)
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Residual stress in clinched joints of metals
- 2002
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Ingår i: Applied Physics A. - : Springer. - 0947-8396 .- 1432-0630. ; 74:SUPPL.II, s. s1440-s1442
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Tidskriftsartikel (refereegranskat)abstract
- Diffraction methods are used for the determination of characteristic residual stress (RS) distributions in undismantled clinched samples for the assessment of the influence of RS on the mechanical behaviour of clinched joints. While X-ray diffraction enables merely the determination of near-surface RS distributions, the higher penetration depth of neutron radiation allows the determination of triaxial RS states inside the material. In addition, the complex geometry of clinched joints restricts the application of X-ray RS analysis. Therefore a combined RS determination by X-ray and neutron diffraction has been used to obtain an expressive assessment of the RS distributions in the immediate vicinity of clinched joints. Two different materials with different mechanical behaviour were used for clinching, as well as two different common clinching techniques.
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| 5. |
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| 6. |
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| 7. |
- Peng, Ru, 1960-, et al.
(författare)
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Characterisation of residual stress distribution in clinching joints of carbon steel by diffraction methods
- 2003
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 19:3, s. 336-342
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Tidskriftsartikel (refereegranskat)abstract
- Sheet joints of carbon steel fabricated by two different clinching methods, namely TOX and Eckold, have been investigated. The holding force of the joints was determined by shear tension tests and the deformation microstructure was characterised using optical microscopy. The surface residual stress and mean residual stress distributions as a function of increasing distance from the outer diameter of the interlock button were mapped by X-ray and neutron diffractometry, respectively.The Eckold joints showed more severe joint distortion in the form of global sheet bending, but nevertheless possessed higher shear tension strength than the TOX joints. Characteristic residual stress distributions depending on the clinching method were found in both the TOX and Eckold joints. The observed residual stress distributions have been attributed to the different die construction employed by the two methods, which permitted different degrees of plastic deformation during clinching.
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