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- Lundin, Per, 1971, et al.
(författare)
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A study of the surface integrity after machining by means of non-destructive testing methods
- 2013
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Ingår i: Proceedings of the International Conference on Advanced Manufacturing Engineering and Technologies Vol. 2. - Stockholm. - 9789175018935 ; , s. 283-292
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Konferensbidrag (refereegranskat)abstract
- During metal machining, depending on the cutting conditions, surface and subsurface microstructure alteration are occasionally observed. These alternations are normally referred as “white” and “dark” layers. Due to their different mechanical properties in comparison to the unaffected material, they will have an impact on the finished part. Controlling the quality of the machined parts regarding the surface microstructure alteration by means of non-destructive testing (NDT) methods would be beneficial from production point of view. In this study, the surface integrity of AISI 52100 steel machined at different cutting conditions resulting in white and dark layers with different characteristics were studied. Surface topography, microstructure and residual stresses were examined by using light scattering, optical microscopy and x-ray diffraction (XRD) techniques. Whilst surface characterization was emphasized, one NDT method – magnetic Barkhausen noise (BN) technique – is not well defined for this purpose. The correlation between all the applied techniques was therefore investigated and a preliminary model was developed for the influence of surface roughness, stress conditions and white and dark layer thicknesses on BN signal.
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| 7. |
- Dymitrow, Mirek, et al.
(författare)
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Transcending the rural-urban meme: Hammarkullen – a landscape caught in-between
- 2014
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Ingår i: Unraveling the logics of landscape. Eds.: Stenseke, M., Dymitrow, M., Saltzman, K. et al.; 26th session of the Permanent European Conference for the Study of the Rural Landscape, 8–12 September, University of Gothenburg, Gothenburg & Mariestad, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- People’s different relations towards their environment are always the result of how they perceive it and how different spatialities are ascribed symbolic meaning. Taking into account these relations when formulating policies aimed at solving various problems could offer valuable knowledge for more sustainable planning and management. In certain areas, however, achieving this goal might prove extra problematic due to the preconceived vision of how problems associated with certain spatialities ought to be handled. Hammarkullen, a suburb of Gothenburg, is an extreme example of this. For decades facing socio-economic and structural problems, the struggles of Hammarkullen could be described as a “wicked problem”. Many programs have been undertaken to address it, the latest of which is one of Sweden’s largest EU-projects within urban development. In light of the considerable criticism it has received, we evaluated its inadequacy to solve the identified problems through three case studies. We conclude that a major contributing factor is the urban bias impregnating the design of urban development projects. It happens because the concept of “urbanity” is not one-dimensional (there are at least 40 attributes defining it); moreover it is juxtaposed “rurality” as its conceptual counterpart. Since any of the constitutive attributes is neither fully “rural” nor “urban”, different spatialities assume manifold overlapping combinations. Although Hammarkullen has an urban morphology, many of its attributes fall within the conceptual range of “rurality”, and should be addressed accordingly. However, since urbanity is most often viewed as morphology, the “urban shell” of Hammarkullen inadvertently prompts “urban” development projects. In that light, we resort to a landscape approach as an alternative conceptual tool to circumvent the rural-urban impasse in problem-solving. As a relational, non-essentialist technique, a landscape approach has the potential to capture the individual needs of each spatiality, including those that are not necessarily aligned with a conceptual rural-urban axis.
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- Ghajargar, Maliheh, 1980-, et al.
(författare)
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The UX of Interactive Machine Learning
- 2020
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Ingår i: NordiCHI 2020, 11th Nordic Conference on Human-Computer Interaction: Shaping Experiences, Shaping Society. - New York, USA : Association for Computing Machinery (ACM).
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Konferensbidrag (refereegranskat)abstract
- Machine Learning (ML) has been a prominent area of research within Artificial Intelligence (AI). ML uses mathematical models to recognize patterns in large and complex data sets to aid decision making in different application areas, such as image and speech recognition, consumer recommendations, fraud detection and more. ML systems typically go through a training period in which the system encounters and learns about the data; further, this training often requires some degree of human intervention. Interactive machine learning (IML) refers to ML applications that depend on continuous user interaction. From an HCI perspective, how humans interact with and experience ML models in training is the main focus of this workshop proposal. In this workshop we focus on the user experience (UX) of Interactive Machine Learning, a topic with implications not only for usability but also for the long-term success of the IML systems themselves.
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- Holmberg, Joakim, et al.
(författare)
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VerOpt - MATLAB Driven Versatile Optimization
- 2001
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Ingår i: Program and proceedings for the Nordic MATLAB Conference Oslo, October 17-18, 2001. - Trondheim : Comsol. - 8299595509 ; , s. 207-212
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- VerOpt, a MATLAB driven versatile optimization environment, enables the choice of a suitable optimization routine, parallelization over TCP/IP and the use of external solvers. VerOpt is the result of working towards the creation of a versatile yet effective environment for applied optimization studies. This paper presents the concepts behind VerOpt, including how and why we use parallelization, and the lessons learnt when using external solvers. The paper also gives a comparison of implemented optimization routines when applied to test problems. Currently, links to three external solvers are implemented. Two of them come from the commercial software market for engineering solutions: ANSYS (version 5.6 University High), a general purpose FE-code and C-MOLD (version 2000.7.1), a code for injection molding. The third solver is from the academic world, AnyBody, a code for biomechanical studies. The implemented optimization routines referred to are Method of Moving Asymptotes (MMA), Simulated Annealing (SA) and a genetic algorithm (GA). The MMA is a gradient-based algorithm whereas the other two can be classified as stochastic. The results of the comparison of the implemented optimization routines, in which �fmincon� from the MATLAB Optimization Toolbox is also used, show that MMA is generally the fastest routine, but does not always find the best solution. However, in test cases when parallelization is used the comparison is not ideal, since the parallelization procedures for the algorithms are not equivalent. When optimization routines are based on numerically computed gradients, such as MMA, they are embarrassingly parallel. This is because the gradients are independent of each other, which makes it possible to compute them simultaneously, but on different processors. For a stochastic routine such as SA a different approach is needed. In our case we have used a simple form of domain decomposition. An interesting result is that, in the test case involving ANSYS, we found that using ANSYS alone, as solver as well as optimizer, did not give such a good solution as using VerOpt. A clear future development is to add a greater number of different types of optimization routines. A possible future development is to transform VerOpt into something that is more akin to a regular style MATLAB Toolbox. Irrespective of this development, VerOpt will be a significant aid for education as well as research in applied optimization. It will also serve the authors as the environment for further research in the fields of injection molding and biomechanics.
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