| 1. |
- Fathi, Masood, et al.
(författare)
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Unveiling the Potential of Mixed Reality : Enhancing Time Measurement and Operator Support in Manual Assembly Processes
- 2024
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Ingår i: Procedia Computer Science. - : Elsevier. - 1877-0509. ; 232, s. 2670-2679
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the potential of Mixed Reality (MR) in the manual assembly processes and conducts a case study at a pump manufacturing plant in Sweden. An MR solution is developed to assist operators through visual instructions and guiding aides. The solution also captures the operator's motions using advanced hand and eye tracking features for real-time guidance and accurate time measurement. The proposed MR solution uses the build feature of HoLolens and a workstation editor, which facilitates the use of the solution in diverse assembly environments. The results of the experiments show that the developed MR solution can improve operator support, reduce errors, and enhance the overall efficiency of manual assembly processes. Moreover, it is shown to be an efficient tool for time measurement of the manual assembly process that has promising potential to replace sophisticated and time-consuming traditional time study methods.
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| 2. |
- Karlsson, Matts Ingemar, et al.
(författare)
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Birch establishes anywhere! So, what is there to know about natural regeneration and direct seeding of birch?
- 2024
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Ingår i: New Forests. - 0169-4286 .- 1573-5095. ; 55, s. 157-171
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Tidskriftsartikel (refereegranskat)abstract
- We tested three soil scarification approaches of varying intensity (intensive preparation exposing bare mineral soil, medium intensity with a mixture of organic material and mineral soil, and control without site preparation) on six clear-felled sites in two localities in northern and central Sweden between 2018 and 2021. The effect of soil scarification intensity and soil moisture on the occurrence of naturally regenerated birch seedlings was tested one, two and three years after soil scarification, and the density of direct-seeded birch seedlings one year after seeding. In addition, we tested the effect of the annual seed rain, and differences between the two birch species, on the density of direct-seeded seedlings. Soil scarification and its interaction with soil moisture had a significant positive effect on both the occurrence of naturally regenerated birch seedlings and the density of direct-seeded birch seedlings. There was no significant effect of neither annual natural seed rain nor species choice on direct-seeded seedling density. Time since soil scarification had a significant effect on the occurrence of naturally regenerated birch seedlings. In moist soils with high volumetric water content (>= 28%), birch seeds germinate at high rates and seedlings survive without soil scarification. In mesic soils, birch seeds germinate with higher rates after soil scarification. In dry soils, birch seeds rarely germinate regardless of any disturbance of the humus layer.
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| 3. |
- Pehrsson, Leif, 1970-, et al.
(författare)
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Optimisation with multi-objective rule extraction for manufacturing management
- 2022
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Ingår i: International Journal of Manufacturing Research. - : InderScience Publishers. - 1750-0591 .- 1750-0605. ; 17:4, s. 452-475
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Tidskriftsartikel (refereegranskat)abstract
- Industry is foreseeing rapid developments in the ability tocapture data within its manufacturing operations and the interest in methodsfor extracting knowledge from such data is increasing. Through digitalrepresentations of manufacturing operations, future scenarios can be modeledand developed with analysis tools based on simulation in combination withmulti-objective optimisation. The results from such analysis tools may bechallenging to interpret, especially when expanding the scope to searchingfor information patterns. An emerging multi-objective rule extraction method,with the ability to handle discrete input parameters, has been furtherdeveloped towards integration in an intelligent decision support system.
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| 4. |
- Schmidt, Bernard, 1981-, et al.
(författare)
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Augmented Reality Approach for a User Interface in a Robotic Production System
- 2022
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Ingår i: SPS2022. - Amsterdam; Berlin; Washington, DC : IOS Press. - 9781643682686 - 9781643682693 ; , s. 240-251
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Konferensbidrag (refereegranskat)abstract
- In a Cyber-physical system, the information flow from the cyber part to the physical part plays a crucial role. This paper presents the work of development and initial testing of an augmented reality approach to provide a user interface for operators that could be a part of a robotic production system. The solution is distributed and includes a communication hub that allows the exchange of data and information between multiple clients e.g. robot controllers, an optimization platform, and visualization devices. The main contributions of the presented work are visualization of optimization results and visualization of information obtained from the robot controller and the integrated communication framework. The paper also presents challenges faced during the development work and opportunities related to the presented approach. The implemented interface uses HoloLens 2 mixed reality device to visualize in real-time information obtained from a robot controller as well as from simulation. Information regarding the placement of work objects and targets or currently executed lines of code can be useful for robotic cell programmers and commissioning teams to validate robot programs and to select more optimal solutions toward sustainable manufacturing. The operator can simulate the execution of the robot program and visualize it by overlying the robot cell with the 3D model of the simulated robot. Moreover, visualization of future robot motion could support human-robot collaboration. Furthermore, the interface allows providing the user with details from multi-objective optimization performed on a digital twin of the robotic cell with the aim to reduce cycle time and energy consumption. It allows visualizing selected scenarios to support decision-making by allowing comparison of proposed solutions and the initial one. The visualization includes cell layout, robot path, cycle time, robot energy consumption. The presented approach is demonstrated in industry-inspired cases and with the use of an industrial ABB robot.
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| 5. |
- Karlsson, Ingemar, et al.
(författare)
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Online Knowledge Extraction and Preference Guided Multi-Objective Optimization in Manufacturing
- 2021
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 9, s. 145382-145396
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Tidskriftsartikel (refereegranskat)abstract
- The integration of simulation-based optimization and data mining is an emerging approach to support decision-making in the design and improvement of manufacturing systems. In such an approach, knowledge extracted from the optimal solutions generated by the simulation-based optimization process can provide important information to decision makers, such as the importance of the decision variables and their influence on the design objectives, which cannot easily be obtained by other means. However, can the extracted knowledge be directly used during the optimization process to further enhance the quality of the solutions? This paper proposes such an online knowledge extraction approach that is used together with a preference-guided multi-objective optimization algorithm on simulation models of manufacturing systems. Specifically, it introduces a combination of the multi-objective evolutionary optimization algorithm, NSGA-II, and a customized data mining algorithm, called Flexible Pattern Mining (FPM), which can extract knowledge in the form of rules in an online and automatic manner, in order to guide the optimization to converge towards a decision maker's preferred region in the objective space. Through a set of application problems, this paper demonstrates how the proposed FPM-NSGA-II can be used to support higher quality decision-making in manufacturing.
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| 6. |
- Fadil, Hassan, 1990-
(författare)
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New Experimental and Modelling Tools for Multiscale Characterization of Asphalt Mastic
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Asphalt mastics act as a binding phase in asphalt mixtures and their rheological properties strongly affect the performance of asphalt mixtures with respect to virtually all damage modes. In order to measure mastics properties, relevant for field performance, testing should be performed at size-scales representative for the morphology and material inhomogeneity of asphalt mixtures. This thesis aims to contribute to solving these important issues by developing new experimental and modelling tools for the multi-scale characterization of asphalt mastics.An instrumented indentation test for viscoelastic characterization of asphalt mastics is proposed as a new alternative to existing techniques. A methodology for spherical indentation testing of bituminous materials is developed allowing measuring their viscoelastic properties at arbitrary non-decreasing loading. The potential of indentation tests for multi-scale measurements of viscoelastic properties of binder-aggregate composites is investigated for the special case of asphalt mortar, composed of mastic and aggregates smaller than 2.36 mm. The effect of the test parameters on the measured apparent shear relaxation modulus of asphalt mortar is evaluated. Experimental and modelling results indicate that the measurement scale in the indentation tests can be controlled efficiently by testing with different indenter-specimen contact areas. Accordingly, indentation tests may be used for reliable viscoelastic characterization of binder-aggregate composites on macro-scale as well as on the mastic phase level. It may thus potentially provide a relatively simple tool for measuring viscoelastic properties of mastics in situ in asphalt mixtures. In order to establish a quantitative link between material design parameters of mastics and its rheology, a new finite element (FE) micromechanical modelling approach has been developed. It allows predicting the viscoelastic properties of bitumen-filler mastic from its volumetric, mechanical and geometrical design parameters. The influence of modelling parameters on the model’s accuracy is evaluated and optimal parameter combinations are identified. The model is validated with the measurements performed on several mastics and for a range of volumetric concentration of filler. It is shown that the proposed model can capture the measured viscoelastic behaviour of mastics for the examined range of loading, temperature and material parameters. Accordingly, it may be a useful tool for optimizing mastics material design for the target viscoelastic properties.
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| 7. |
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| 8. |
- Karlsson, Ingemar
(författare)
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An interactive decision support system using simulation-based optimization and knowledge extraction
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of simulation to improve existing manufacturing systems is not new, but simulation can also be used increase the understanding of production systems that have not yet been built. The power of simulation models can be further enhanced by using simulation-based optimization, in which an optimization algorithm tries to find optimal solutions, given certain objectives. However, extracting knowledge from the data resulting from simulation experiments and simulation-based optimization is a complex task. Therefore, tools are needed to assist users in this task. These tools can be visual, like diagrams, or can be generated by data mining. The process of running a study using simulation-based optimization to extract knowledge is a manual task that can in part be automated using existing tools, but to the author’s knowledge there is no software that implements the complete process. This work aims to develop a novel decision support system to support the generic decision process when using simulation and simulation-based optimization. The first step in setting up such a system is to understand how industry currently uses simulation and simulation-based optimization in manufacturing operations. Thus a questionnaire was distributed to manufacturing companies and organizations. The results showed that these techniques are being used, but that companies want more help with the analysis of the results as well as an automated guide in the decision process. This work proposes a system that supports a generic decision process by providing a tool with which a user can define a workflow in their organization, using simulation-based optimization as one component. The decision support system then provides tools for extracting knowledge in the form of diagrams and performs data mining for automated analysis. Data mining is part of the workflow as a tool for extracting knowledge after an optimization, as well as a tool for guiding optimization to suit the users’ preferences. The decision support system also provides for visualization of simulation models and optimization results using augmented reality. A head-mounted display helps users to see the results and model behaviors in 3D. This technology also makes it possible for users to collaborate, both in the same location and remotely. These visual and automatic analysis tools are shown to be effective in several application studies of real-world production scenarios in which data mining has been used to extract important knowledge that would be hard to obtain manually. Together with the automated workflow and efficient visualization of simulation and optimization results in augmented reality, the decision support system is believed to be an effective tool for extracting knowledge for general production systems design and analysis.
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| 9. |
- Holmström, Emma, et al.
(författare)
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Modeling birch seed supply and seedling establishment during forest regeneration
- 2017
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800. ; 352, s. 31-39
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Tidskriftsartikel (refereegranskat)abstract
- The seed ecology and regeneration management of birch species in Fennoscandia has been quite thoroughly investigated through decades of forestry research. Nonetheless, there are few methods for precise predictions of spontaneous natural regeneration. In this study a first framework of a model is presented that combines possible seed supply with seed emergence and seedling survival based on GIS data and the results of past experiments. The birch seed supply was calculated by combining spatial data on standing birch volume with birch seed dispersal distributions. The establishment on a site was further estimated based on the effect parameters of soil moisture conditions and soil scarification. This model shows a reduced variance compared to general means of seed supply and partly explains the variation between sites with the same soil scarification treatments. Even though additional management and ecological variables should be incorporated to increase the model's predictive ability, it could already be of use in practical forestry. (C) 2017 Elsevier B.V. All rights reserved.
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| 10. |
- Karlsson, Ingemar, et al.
(författare)
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Combining augmented reality and simulation-based optimization for decision support in manufacturing
- 2017
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Ingår i: Proceedings of the 2017 Winter Simulation Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538634288 - 9781538634295 - 9781538634301 ; , s. 3988-3999
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Konferensbidrag (refereegranskat)abstract
- Although the idea of using Augmented Reality and simulation within manufacturing is not a new one, the improvement of hardware enhances the emergence of new areas. For manufacturing organizations, simulation is an important tool used to analyze and understand their manufacturing systems; however, simulation models can be complex. Nonetheless, using Augmented Reality to display the simulation results and analysis can increase the understanding of the model and the modeled system. This paper introduces a decision support system, IDSS-AR, which uses simulation and Augmented Reality to show a simulation model in 3D. The decision support system uses Microsoft HoloLens, which is a head-worn hardware for Augmented Reality. A prototype of IDSS-AR has been evaluated with a simulation model depicting a real manufacturing system on which a bottleneck detection method has been applied. The bottleneck information is shown on the simulation model, increasing the possibility of realizing interactions between the bottlenecks.
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