| 11. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Metamodel based multi-objective optimization of a turning process by using finite element simulation
- 2020
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Ingår i: Engineering optimization (Print). - : Taylor & Francis Group. - 0305-215X .- 1029-0273. ; 52:7, s. 1261-1278
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the advantages and potentials of the metamodelbased multi-objective optimization (MOO) of a turning operation through the application of finite element simulations and evolutionary algorithms to a metal cutting process. The objectives are minimizing the interface temperature and tool wear depth obtained from FE simulations using DEFORM2D software, and maximizing the material removal rate. Tool geometry and process parameters are considered as the input variables. Seven metamodelling methods are employed and evaluated, based on accuracy and suitability. Radial basis functions with a priori bias and Kriging are chosen to model tool–chip interface temperature and tool wear depth, respectively. The non-dominated solutions are found using the strength Pareto evolutionary algorithm SPEA2 and compared with the non-dominated front obtained from pure simulation-based MOO. The metamodel-based MOO method is not only advantageous in terms of reducing the computational time by 70%, but is also able to discover 31 new non-dominated solutions over simulation-based MOO.
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| 12. |
- Amouzgar, Kaveh, 1980-
(författare)
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Metamodel Based Multi-Objective Optimization with Finite-Element Applications
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As a result of the increase in accessibility of computational resources and the increase of computer power during the last two decades, designers are able to create computer models to simulate the behavior of complex products. To address global competitiveness, companies are forced to optimize the design of their products and production processes. Optimizing the design and production very often need several runs of computationally expensive simulation models. Therefore, integrating metamodels, as an efficient and sufficiently accurate approximate of the simulation model, with optimization algorithms is necessary. Furthermore, in most of engineering problems, more than one objective function has to be optimized, leading to multi-objective optimization(MOO). However, the urge to employ metamodels in MOO, i.e., metamodel based MOO (MB-MOO), is more substantial.Radial basis functions (RBF) is one of the most popular metamodeling methods. In this thesis, a new approach to constructing RBF with the bias to beset a priori by using the normal equation is proposed. The performance of the suggested approach is compared to the classic RBF and four other well-known metamodeling methods, in terms of accuracy, efficiency and, most importantly, suitability for integration with MOO evolutionary algorithms. It has been found that the proposed approach is accurate in most of the test functions, and it was the fastest compared to other methods. Additionally, the new approach is the most suitable method for MB-MOO, when integrated with evolutionary algorithms. The proposed approach is integrated with the strength Pareto evolutionary algorithm (SPEA2) and applied to two real-world engineering problems: MB-MOO of the disk brake system of a heavy truck, and the metal cutting process in a turning operation. Thereafter, the Pareto-optimal fronts are obtained and the results are presented. The MB-MOO in both case studies has been found to be an efficient and effective method. To validate the results of the latter MB-MOO case study, a framework for automated finite element (FE) simulation based MOO (SB-MOO) of machining processes is developed and presented by applying it to the same metal cutting process in a turning operation. It has been proved that the framework is effective in achieving the MOO of machining processes based on actual FE simulations.
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| 13. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Multi-objective optimisation of tool indexing problem : a mathematical model and a modified genetic algorithm
- 2021
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Ingår i: International Journal of Production Research. - : Taylor & Francis Group. - 0020-7543 .- 1366-588X. ; 59:12, s. 3572-3590
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Tidskriftsartikel (refereegranskat)abstract
- Machining process efficiencies can be improved by minimising the non-machining time, thereby resulting in short operation cycles. In automatic-machining centres, this is realised via optimum cutting tool allocation on turret-magazine indices – the “tool-indexing problem”. Extant literature simplifies TIP as a single-objective optimisation problem by considering minimisation of only the tool-indexing time. In contrast, this study aims to address the multi-objective optimisation tool indexing problem (MOOTIP) by identifying changes that must be made to current industrial settings as an additional objective. Furthermore, tool duplicates and lifespan have been considered. In addition, a novel mathematical model is proposed for solving MOOTIP. Given the complexity of the problem, the authors suggest the use of a modified strength Pareto evolutionary algorithm combined with a customised environment-selection mechanism. The proposed approach attained a uniform distribution of solutions to realise the above objectives. Additionally, a customised solution representation was developed along with corresponding genetic operators to ensure the feasibility of solutions obtained. Results obtained in this study demonstrate the realization of not only a significant (70%) reduction in non-machining time but also a set of tradeoff solutions for decision makers to manage their tools more efficiently compared to current practices.
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| 14. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Multi-objective optimization of material model parameters of an adhesive layer by using SPEA2
- 2015
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Ingår i: Advances in structural and multidisciplinary optimization. - : The International Society for Structural and Multidisciplinary Optimization (ISSMO). - 9780646943947 ; , s. 249-254
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Konferensbidrag (refereegranskat)abstract
- The usage of multi material structures in industry, especially in the automotive industry are increasing. To overcome the difficulties in joining these structures, adhesives have several benefits over traditional joining methods. Therefore, accurate simulations of the entire process of fracture including the adhesive layer is crucial. In this paper, material parameters of a previously developed meso mechanical finite element (FE) model of a thin adhesive layer are optimized using the Strength Pareto Evolutionary Algorithm (SPEA2). Objective functions are defined as the error between experimental data and simulation data. The experimental data is provided by previously performed experiments where an adhesive layer was loaded in monotonically increasing peel and shear. Two objective functions are dependent on 9 model parameters (decision variables) in total and are evaluated by running two FEsimulations, one is loading the adhesive layer in peel and the other in shear. The original study converted the two objective functions into one function that resulted in one optimal solution. In this study, however, a Pareto frontis obtained by employing the SPEA2 algorithm. Thus, more insight into the material model, objective functions, optimal solutions and decision space is acquired using the Pareto front. We compare the results and show good agreement with the experimental data.
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| 15. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Optimizing index positions on CNC tool magazines considering cutting tool life and duplicates
- 2020
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Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271. ; 93, s. 1508-1513
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Tidskriftsartikel (refereegranskat)abstract
- Minimizing the non-machining time of CNC machines requires optimal positioning of cutting tools on indexes (stations) of CNC machine turret magazine. This work presents a genetic algorithm with a novel solution representation and genetic operators to find the best possible index positions while tool duplicates and tools life are taken in to account during the process. The tool allocation in a machining process of a crankshaft with 10 cutting operations, on a 45-index magazine, is optimized for the entire life of the tools on the magazine. The tool-indexing time is considerably reduced compared to the current index positions being used in an automotive factory.
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| 16. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Radial basis functions as surrogate models with a priori bias in comparison with a posteriori bias
- 2017
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Ingår i: Structural and multidisciplinary optimization (Print). - : Springer Science and Business Media LLC. - 1615-147X .- 1615-1488. ; 55:4, s. 1453-1469
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Tidskriftsartikel (refereegranskat)abstract
- In order to obtain a robust performance, the established approach when using radial basis function networks (RBF) as metamodels is to add a posteriori bias which is defined by extra orthogonality constraints. We mean that this is not needed, instead the bias can simply be set a priori by using the normal equation, i.e. the bias becomes the corresponding regression model. In this paper we demonstrate that the performance of our suggested approach with a priori bias is in general as good as, or even for many test examples better than, the performance of RBF with a posteriori bias. Using our approach, it is clear that the global response is modelled with the bias and that the details are captured with radial basis functions. The accuracy of the two approaches are investigated by using multiple test functions with different degrees of dimensionality. Furthermore, several modeling criteria, such as the type of radial basis functions used in the RBFs, dimension of the test functions, sampling techniques and size of samples, are considered to study their affect on the performance of the approaches. The power of RBF with a priori bias for surrogate based design optimization is also demonstrated by solving an established engineering benchmark of a welded beam and another benchmark for different sampling sets generated by successive screening, random, Latin hypercube and Hammersley sampling, respectively. The results obtained by evaluation of the performance metrics, the modeling criteria and the presented optimal solutions, demonstrate promising potentials of our RBF with a priori bias, in addition to the simplicity and straight-forward use of the approach.
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| 17. |
- Andersson, Joacim, 1978-, et al.
(författare)
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The 'body pedagogics' of an elite footballer's career path - analysing Zlatan Ibrahimovic's biography
- 2017
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Ingår i: Physical Education and Sport Pedagogy. - : Taylor & Francis. - 1740-8989 .- 1742-5786. ; 22:5, s. 502-517
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pedagogical research on career is encouraged to not limit sport learning to athletic skills, coaching effectiveness and coach–athlete relationships, but to also focus on learning in a multidimensional sense in the context of an athlete’s individual and social biography. This article examines an elite athlete’s career path as a body pedagogic phenomenon involving processes of self-transformation in relation to practical, social and embodied environments.Purpose: The purpose is to analyse the career path of the elite footballer Zlatan Ibrahimovic by focusing on how different learning environments relate to different embodiments of techniques and skills and how values and norms shape professionalism.Theoretical frameworks: A combined framework of body pedagogics and John Dewey’s theory of aesthetic experience is used to understand an elite career path as a learning trajectory involving different self-transformation means. Hence, the elite athlete is viewed as a career climber who creates his own educational pathway and engages in processes of participating, acquiring and becoming.Data analysis: A practical epistemology analysis (PEA) with a focus on aesthetic judgements is used to analyse the narrative of Zlatan’s career path as it is portrayed in the biography I Am Zlatan: My Story on and Off the Field. One major theme is identified, namely that Zlatan develops from being a dribbler to a striker. Against this background, Zlatan Ibrahomovic’s self-transformation is scrutinised in relation to three different sub-themes (suburb, arena and team) in three different ways (auto-didactic, education and educator) to create distinct and heterogeneous forms of knowledge in support of professional artistry.Results: The analysis offers an elaborated empirical description of how the means and ends of self-transformation develop reciprocally throughout Zlatan’s elite career and how this relates to practical, social and embodied environments. Examples of body pedagogic outcomes are: (1) different commitments to training, team culture and the coach–athlete relationship (social), (2) that Zlatan uses his dribbling skills more purposefully for scoring goals and satisfying the coach (embodied) and (3) that he is able to win different leagues and titles with different teams (practical).
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| 18. |
- Andersson, Lena, et al.
(författare)
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Living with heart failure without realising : A qualitative patient study
- 2012
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Ingår i: British Journal of Community Nursing. - : MA Healthcare Ltd.. - 1462-4753 .- 2052-2215. ; 17:12, s. 630-637
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Tidskriftsartikel (refereegranskat)abstract
- Heart failure is an important problem in Swedish primary healthcare as in the UK. In spite of that little is known about how people with heart failure experience support from primary healthcare. This paper investigates how people with heart failure experience support in primary healthcare. Semi structured interviews were conducted with five men and five women, born 1922-1951. The interviews were analyzed with qualitative content analysis in accordance with Graneheim and Lundman (2004). The participants experienced they had not received information about their diagnosis or about the cause of their condition. They had not been informed they had heart failure. Instead the participants believed their symptoms were caused by age, thus being part of normal ageing. They did not experience they needed care or support to cope with illness or disease. Instead their main needs for support in daily life concerned help with practical matters.There is a risk primary healthcare abandons people with heart failure meaning the patients are forced to develop strategies on their own in order to manage symptoms. When inadequately informed there is also a risk they make up their own explanations signifying possible difficulties to handle their health situation.
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| 19. |
- Andreasson, Rebecca, et al.
(författare)
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Affective Touch in Human-Robot Interaction: Conveying Emotion to the Nao Robot
- 2018
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Ingår i: International Journal of Social Robotics. - : Springer Science and Business Media LLC. - 1875-4791 .- 1875-4805. ; 10:4, s. 473-491
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Tidskriftsartikel (refereegranskat)abstract
- Affective touch has a fundamental role in human development, social bonding, and for providing emotional support in interpersonal relationships. We present, what is to our knowledge, the first HRI study of tactile conveyance of both positive and negative emotions (affective touch) on the Nao robot, and based on an experimental set-up from a study of human-human tactile communication. In the present work, participants conveyed eight emotions to a small humanoid robot via touch. We found that female participants conveyed emotions for a longer time, using more varied interaction and touching more regions on the robot's body, compared to male participants. Several differences between emotions were found such that emotions could be classified by the valence of the emotion conveyed, by combining touch amount and duration. Overall, these results show high agreement with those reported for human-human affective tactile communication and could also have impact on the design and placement of tactile sensors on humanoid robots.
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| 20. |
- Andreasson, Rebecca, et al.
(författare)
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Distributed Cognition in Manufacturing : Collaborative Assembly Work
- 2016
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Ingår i: Advances in Manufacturing Technology XXX. - : IOS Press. - 9781614996675 - 9781614996682 ; , s. 243-248
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Konferensbidrag (refereegranskat)abstract
- Cognitive science is becoming increasingly central within humanfactors and ergonomics (HF&E) and there has long been a call for a more systemicperspective in the area with a somewhat broader unit of analysis. This paperpresents a case study applying the theoretical framework of distributed cognition(DCog), which shows how DCog would offer a more complete understanding ofmanufacturing within its greater context, including the social, cultural, andmaterial surroundings. This paper aims to characterize and analyse dock assemblyof forest machines as a complex socio-technical system from a DCog perspective;focusing on the creation of enacted landscapes in this particular setting. The paperalso exemplifies benefits of using the DCog framework in the manufacturingdomain as a way of grasping the assembly workers’ tacit competence and skills.
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