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- Heintz, Per, 1975, et al.
(författare)
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Adaptive strategies and error control for computing material forces in fracture mechanics
- 2004
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Ingår i: International Journal for Numerical Methods in Engineering. - : Wiley. - 0029-5981 .- 1097-0207. ; 60:7, s. 1287-1299
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Tidskriftsartikel (refereegranskat)abstract
- The concept of material forces pertains to a variation of the inverse motion map while the placement field is kept fixed. From the weak formulation of the self-equilibrating Eshelby (material) stress tensor it turns out that the classical J-integral formulations in fracture mechanics are just special cases due to the choice of particular weight functions. In this contribution, we discuss a posteriori error control of the material forces as part of an adaptive strategy to reduce the discretization error to an acceptable level. The data of the dual problem involves the quite non-conventional tangent stiffness of the (material) Eshelby stress tensor with respect to a variation of the (physical) strain field. The suggested strategy is applied to the common fracture mechanics problem of a single-edged crack, whereby different strategies for computing the J-integral are compared. We also consider the case in which the crack edges are not parallel, i.e. a notch.
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- Heintz, Fredrik, 1975-, et al.
(författare)
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Chronicle Recognition in the WITAS UAV Project: A Preliminary Report
- 2001
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Ingår i: Proceedings of the Swedish AI Society Workshop.
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Konferensbidrag (refereegranskat)abstract
- This paper describes the chronicle recognition problem and reports its status in the WITAS UAV project. We describe how we use the IxTeT chronicle recognition system to define chronicles (scenarios or situations), like a vehicle passing another vehicle, and how it is incorporated in the WITAS architecture. We also discuss known problems with the current system and possible directions of future research.
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- Heintz, Fredrik, 1975-, et al.
(författare)
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DyKnow : A Framework for Processing Dynamic Knowledge and Object Structures in Autonomous Systems
- 2004
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Ingår i: Proceedings of the International Workshop on Monitoring, Security, and Rescue Techniques in Multi-Agent Systems (MSRAS). - Berlin/Heidelberg : Springer. - 9783540232452 ; , s. 479-492
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Konferensbidrag (refereegranskat)abstract
- Any autonomous system embedded in a dynamic and changing environment must be able to create qualitative knowledge and object structures representing aspects of its environment on the fly from raw or preprocessed sensor data in order to reason qualitatively about the environment. These structures must be managed and made accessible to deliberative and reactive functionalities which are dependent on being situationally aware of the changes in both the robotic agent’s embedding and internal environment. DyKnow is a software framework which provides a set of functionalities for contextually accessing, storing, creating and processing such structures. The system is implemented and has been deployed in a deliberative/reactive architecture for an autonomous unmanned aerial vehicle. The architecture itself is distributed and uses real-time CORBA as a communications infrastructure. We describe the system and show how it can be used in execution monitoring and chronicle recognition scenarios for UAV applications.
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- Heintz, Fredrik, 1975-, et al.
(författare)
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Simulated RoboCup in University Undergraduate Education
- 2000
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Ingår i: Proceedings of the Fourth Internation Workshop on RoboCup. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783540421856 - 9783540453246 ; , s. 309-314
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Konferensbidrag (refereegranskat)abstract
- We argue that RoboCup can be used to improve the teaching of AI in undergraduate education. We give some examples of how AI courses using RoboCup can be implemented using a problem based approach at two different Universities. To reduce the negative aspects found we present a solution, with the aim of easing the burden of grasping the domain of RoboCup for the students, RoboSoc which is a general framework for developing simulated RoboCup agents.
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- Heintz, Fredrik, 1975-, et al.
(författare)
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Using Simulated RoboCup to Teach AI in Undergraduate Education
- 2001
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Ingår i: Proceedings of the 7th Scandinavian Conference on Artificial Intelligence (SCAI). - : IOS Press. - 1586031619 ; , s. 13-21
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Konferensbidrag (refereegranskat)abstract
- In this paper we argue that RoboCup is a useful tool for the teaching of AI in undergraduate education. We provide case studies, from two Swedish universities, of how RoboCup based AI courses can be implemented using a problem based approach. Although the courses were successful there are significant areas for improvement. Firstly, to help students cope with the complexity of the domain we developed RoboSoc, a general software framework for developing simulated RoboCup agents. Secondly, we propose creating close co-operation between the teachers and researchers at Scandinavian Universities with the aim of increasing the motivation of both students and teachers by providing accessible information and competence.
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