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  • 1.
    Adamson, Göran
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. De Montfort University, UK.
    A Novel Method for Adaptive Control of Manufacturing Equipment in Cloud Environments2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The ability to adaptively control manufacturing equipment, both in local and distributed environments, is becoming increasingly more important for many manufacturing companies.

    One important reason for this is that manufacturing companies are facing increasing levels of changes, variations and uncertainty, caused by both internal and external factors, which can negatively impact their performance. Frequently changing consumer requirements and market demands usually lead to variations in manufacturing quantities, product design and shorter product life-cycles. Variations in manufacturing capability and functionality, such as equipment breakdowns, missing/worn/broken tools and delays, also contribute to a high level of uncertainty. The result is unpredictable manufacturing system performance, with an increased number of unforeseen events occurring in these systems. Events which are difficult for traditional planning and control systems to satisfactorily manage.

    For manufacturing scenarios such as these, the use of real-time manufacturing information and intelligence is necessary to enable manufacturing activities to be performed according to actual manufacturing conditions and requirements, and not according to a pre-determined process plan. Therefore, there is a need for an event-driven control approach to facilitate adaptive decision-making and dynamic control capabilities.

    Another reason driving the move for adaptive control of manufacturing equipment is the trend of increasing globalization, which forces manufacturing industry to focus on more cost-effective manufacturing systems and collaboration within global supply chains and manufacturing networks. Cloud Manufacturing is evolving as a new manufacturing paradigm to match this trend, enabling the mutually advantageous sharing of resources, knowledge and information between distributed companies and manufacturing units. One of the crucial objectives for Cloud Manufacturing is the coordinated planning, control and execution of discrete manufacturing operations in collaborative and networked environments. Therefore, there is also a need that such an event-driven control approach supports the control of distributed manufacturing equipment.

    The aim of this research study is to define and verify a novel and comprehensive method for adaptive control of manufacturing equipment in cloud environments.

    The presented research follows the Design Science Research methodology. From a review of research literature, problems regarding adaptive manufacturing equipment control have been identified. A control approach, building on a structure of event-driven Manufacturing Feature Function Blocks, supported by an Information Framework, has been formulated. The Function Block structure is constructed to generate real-time control instructions, triggered by events from the manufacturing environment. The Information Framework uses the concept of Ontologies and The Semantic Web to enable description and matching of manufacturing resource capabilities and manufacturing task requests in distributed environments, e.g. within Cloud Manufacturing. The suggested control approach has been designed and instantiated, implemented as prototype systems for both local and distributed manufacturing scenarios, in both real and virtual applications. In these systems, event-driven Assembly Feature Function Blocks for adaptive control of robotic assembly tasks have been used to demonstrate the applicability of the control approach. The utility and performance of these prototype systems have been tested, verified and evaluated for different assembly scenarios.

    The proposed control approach has many promising characteristics for use within both local and distributed environments, such as cloud environments. The biggest advantage compared to traditional control is that the required control is created at run-time according to actual manufacturing conditions.

    The biggest obstacle for being applicable to its full extent is manufacturing equipment controlled by proprietary control systems, with native control languages. To take the full advantage of the IEC Function Block control approach, controllers which can interface, interpret and execute these Function Blocks directly, are necessary.

    Fulltekst (pdf)
    fulltext
  • 2.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Academy of Innovation & Research, Falmouth University, Cornwall, United kingdom.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. KTH Royal Institute of Technology, Stockholm, Sweden.
    A Cloud Service Control Approach for Distributed and Adaptive Equipment Control in Cloud Environments2016Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 41, s. 644-649Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A developing trend within the manufacturing shop-floor domain is the move of manufacturing activities into cloud environments, as scalable, on-demand and pay-per-usage cloud services. This will radically change traditional manufacturing, as borderless, distributed and collaborative manufacturing missions between volatile, best suited groups of partners will impose a multitude of advantages. The evolving Cloud Manufacturing (CM) paradigm will enable this new manufacturing concept, and on-going research has described many of its anticipated core virtues and enabling technologies. However, a major key enabling technology within CM which has not yet been fully addressed is the dynamic and distributed planning, control and execution of scattered and cooperating shop-floor equipment, completing joint manufacturing tasks.

    In this paper, the technological perspective for a cloud service-based control approach is described, and how it could be implemented. Existing manufacturing resources, such as soft, hard and capability resources, can be packaged as cloud services, and combined to create different levels of equipment or manufacturing control, ranging from low-level control of single machines or devices (e.g. Robot Control-as-a-Service), up to the execution of high level multi-process manufacturing tasks (e.g. Manufacturing-as-a-Service). A multi-layer control approach, featuring adaptive decision-making for both global and local environmental conditions, is proposed. This is realized through the use of a network of intelligent and distributable decision modules such as event-driven Function Blocks, enabling run-time manufacturing activities to be performed according to actual manufacturing conditions. The control system’s integration to the CM cloud service management functionality is also described.

    Fulltekst (pdf)
    fulltext
  • 3.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Event-Driven Adaptability using IEC 61499 in Manufacturing Systems2012Inngår i: Proceedings of The 5th International Swedish Production Symposium, SPS12 / [ed] Mats Björkman, Linköping: The Swedish Production Academy , 2012, s. 453-460Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Different kinds of uncertainty, such as variations in manufacturing capability and functionality, as well as changes in demand, make up a dynamically changing environment for many manufacturing systems of today. The ability to adapt to these unforeseen changes, through dynamic decision-making as well as dynamic control capabilities based on the use of real-time manufacturing information and intelligence, is vital to be able to perform at a competitive level while reducing unscheduled downtime. The event-driven Function Block (FB) model of the IEC 61499 standard, as opposed to the time-triggered and data-driven concept of IEC 61331, supports this approach, making it possible to handle, in a responsive and adaptive way, different kinds of uncertainty. Our objective is to develop methodologies for distributed, adaptive and dynamic process planning as well as machine monitoring and control for machining and assembly operations, using event-driven FBs. The implementation and testing of FB-based control for manufacturing equipment has been successfully realized in prototype systems, with control of both CNC machining and robotic assembly operations. The approach of using IEC 61499 FBs for adaptive control in other applications is also investigated, as an adaptive decision support system for operators at manufacturing facilities is under development. We strongly believe that IEC 61499 will play a major role in the shift to adaptive manufacturing systems.

  • 4.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Holm, Magnus
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Moore, Philip
    University College Falmouth, United Kingdom.
    Adaptive Assembly Feature Based Function Block Control of Robotic Assembly Operations2012Inngår i: The 13th Mechatronics Forum International Conference Proceedings: Vol. 1/3 / [ed] Rudolf Scheidl & Bernhard Jakoby, Linz: TRAUNER Verlag, 2012, s. 8-13Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many manufacturing systems are exposed to a variety of unforeseen changes, negatively restricting their performances. External variations depending on market demand (e.g. changes in design, quantity and product mix) and internal variations in production capability and flexibility (e.g. equipment breakdowns, missing/worn/broken tools, delays and express orders) all contribute to an environment of uncertainty. In these dynamically changing environments, adaptability is a key feature for manufacturing systems to be able to perform at a maximum level, while keeping unscheduled downtime to a minimum. Targeting manufacturing equipment adaptability, this paper reports an assembly feature (AF) based approach for robotic assembly, using IEC 61499 compliant Function Blocks (FBs). Through the use of a network of event-driven FBs, an adaptive controller system for an industrial gantry robot’s assembly operations has been designed, implemented and tested. Basic assembly operations have been mapped as AFs into Assembly Feature Function Blocks (AF-FBs). Through their combination in FB networks, they can be aggregated to perform higher level assembly tasks. The AF-FBs dynamic execution and behavior can be adaptively controlled through embedded eventdriven algorithms, enabling the ability of adaptive decisions to handle unforeseen changes in the runtime environment.

  • 5.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system. Department of Production Engineering Royal Institute of Technology 100 44 Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    The state of the art of cloud manufacturing and future trends2013Inngår i: Proceedings of the ASME 2013 International Manufacturing Science and Engineering Conference MSEC2013 June 10-14, 2013, Madison, Wisconsin, USA, ASME - The American Society of Mechanical Engineers , 2013, Vol. 2, s. Article number-, artikkel-id MSEC2013-1123Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cloud manufacturing has emerged as a new manufacturing paradigm, which combines technologies (such as Internet of Things, Cloud computing, semantic Web, virtualisation and service-oriented technologies) with advanced manufacturing models, information and communication technologies. It aims to be networked, intelligent, service-oriented, knowledge-based and energy efficient, and promises a variety of benefits and advantages by providing fast, reliable and secure on-demand services for users. It is envisioned that companies in all sectors of manufacturing will be able to package their resources and know-hows in the Cloud, making them conveniently available for others through pay-as-you-go, which is also timely and economically attractive. Resources, e.g. manufacturing software tools, applications, knowledge and fabrication capabilities, will then be made accessible to presumptive consumers on a worldwide basis. After surveying a vast array of available publications, this paper presents an up-to-date literature review together with future trends and research directions in Cloud manufacturing.

  • 6.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Royal Institute of Technology, Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Falmouth University, Cornwall, UK.
    Adaptive Robot Control as a Service in Cloud Manufacturing2015Inngår i: ASME 2015 International Manufacturing Science and Engineering Conference: Volume 2: Materials; Biomanufacturing; Properties, Applications and Systems; Sustainable Manufacturing, ASME Press, 2015, Vol. 2, s. Paper No. MSEC2015-9479-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The interest for implementing the concept of Manufacturing-as-a-Service is increasing as concepts for letting the manufacturing shop-floor domain take advantage of the cloud appears. Combining technologies such as Internet of Things, Cloud Computing, Semantic Web, virtualisation and service-oriented technologies with advanced manufacturing models, information and communication technologies, Cloud Manufacturing (CM) is emerging as a new manufacturing paradigm. The ideas of on-demand, scalable and pay-for-usage resource-sharing in this concept will move manufacturing towards distributed and collaborative missions in volatile partnerships. This will require a control approach for distributed planning and execution of cooperating manufacturing activities. Without control based on both global and local environmental conditions, the advantages of CM will not be fulfilled.

    By utilising smart and distributable decision modules such as event-driven FBs, run-time manufacturing operations in a distributed environment may be adjusted to prevailing manufacturing conditions. Packaged in a cloud service for manufacturing equipment control, it will satisfy the control needs in CM. By combining different resource types, such as hard, soft and capability resources, the cloud service Robot Control-as-a-Service can be realised.

    This paper describes the functional perspective and enabling technologies for a control approach for robotic assembly tasks in CM, and describes a scenario for its implementation.

  • 7.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Production Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Academy for Innovation & Research, Falmouth University, UK.
    Adaptive Robotic Control in Cloud Environments2014Inngår i: Proceedings of the 24th International Conference on Flexible Automation and Intelligent Manufacturing / [ed] F. Frank Chen, Lancaster, Pennsylvania, USA: DEStech Publications, Inc , 2014, s. 37-44Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The increasing globalization is a trend which forces manufacturing industry of today to focus on more cost-effective manufacturing systems and collaboration within global supply chains and manufacturing networks. Cloud Manufacturing (CM) is evolving as a new manufacturing paradigm to match this trend, enabling the mutually advantageous sharing of resources, knowledge and information between distributed companies and manufacturing units. Providing a framework for collaboration within complex and critical tasks, such as manufacturing and design, it increases the companies’ ability to successfully compete on a global marketplace. One of the major, crucial objectives for CM is the coordinated planning, control and execution of discrete manufacturing operations in a collaborative and networked environment. This paper describes the overall concept of adaptive Function Block control of manufacturing equipment in Cloud environments, with the specific focus on robotic assembly operations, and presents Cloud Robotics as “Robot Control-as-a-Service” within CM.

  • 8.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Department of Production Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Academy for Innovation & Research, Falmouth University, Cornwall, United Kingdom.
    Cloud Manufacturing: A Critical Review of Recent Development and Future Trends2017Inngår i: International journal of computer integrated manufacturing (Print), ISSN 0951-192X, E-ISSN 1362-3052, Vol. 30, nr 4-5, s. 347-380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an on-going paradigm shift in manufacturing, in which modern manufacturing industry is changing towards global manufacturing networks and supply chains. This will lead to the flexible usage of different globally distributed, scalable and sustainable, service-oriented manufacturing systems and resources. Combining recently emerged technologies, such as Internet of Things, Cloud Computing, Semantic Web, service-oriented technologies, virtualisation and advanced high-performance computing technologies, with advanced manufacturing models and information technologies, Cloud Manufacturing is a new manufacturing paradigm built on resource sharing, supporting and driving this change.

    It is envisioned that companies in all sectors of manufacturing will be able to package their resources and know-hows in the Cloud, making them conveniently available for others through pay-as-you-go, which is also timely and economically attractive. Resources, e.g. manufacturing software tools, applications, knowledge and fabrication capabilities and equipment, will then be made accessible to presumptive consumers on a worldwide basis.

    Cloud Manufacturing has been in focus for a great deal of research interest and suggested applications during recent years, by both industrial and academic communities. After surveying a vast array of available publications, this paper presents an up-to-date literature review together with identified outstanding research issues, and future trends and directions within Cloud Manufacturing.

  • 9.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Royal Institute of Technology, Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Falmouth University, Cornwall, United Kingdom.
    Feature-Based Adaptive Manufacturing Equipment Control for Cloud Environments2016Inngår i: Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 2, American Society of Mechanical Engineers (ASME) , 2016, artikkel-id UNSP V002T04A019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ideas of on-demand, scalable and pay-for-usage resource-sharing in Cloud Manufacturing are steadily attracting more interest. For implementing the concept of Manufacturing as-a-Service in a cloud environment, description models and implementation language for resources and their capabilities are required. A standardized approach for systemived virtualization, servisilisation, retrieval, selection and composition into higher levels of functionality is necessary. For the collaborative sharing and use of networked manufacturing resources there is also a need for a control approach for distributed manufacturing equipment. In this paper, the technological perspective for an adaptive cloud service-based control approach is described, and a supporting information model for its implementation. The control is realized through the use of a network of intelligent and distributable Function Block decision modules, enabling run-time manufacturing activities to be performed according to actual manufacturing conditions. The control system's integration to the cloud service management functionality is described, as well as a feature-level capability model and the use of ontologies and the Semantic Web.

  • 10.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Production Engineering KTH Royal Institute of Technology Stockholm, Sweden.
    Holm, Magnus
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moore, Philip
    Academy for Innovation & Research, Falmouth University, Cornwall, United Kingdom.
    Function Block Approach for Adaptive Robotic Control in Virtual and Real Environments2014Inngår i: Proceedings of the 14th Mechatronics Forum International Conference, Mechatronics 2014 / [ed] Leo J. De Vin; Jorge Solis, Karlstad: Karlstads universitet, 2014, s. 473-479Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many manufacturing companies are facing an increasing amount of changes and uncertainty, caused by both internal and external factors. Frequently changing customer and market demands lead to variations in manufacturing quantities, product design and shorter product life-cycles, and variations in manufacturing capability and functionality contribute to a high level of uncertainty. The result is unpredictable manufacturing system performance, with an increased number of unforeseen events occurring in these systems. Such events are difficult for traditional planning and control systems to satisfactorily manage. For scenarios like these, with a dynamically changing manufacturing environment, adaptive decision making is crucial for successfully performing manufacturing operations. Relying on real-time information of manufacturing processes and operations, and their enabling resources, adaptive decision making can be realized with a control approach combining IEC 61499 event-driven Function Blocks (FBs) with manufacturing features. These FBs are small decision-making modules with embedded algorithms designed to generate the desired equipment control code. When dynamically triggered by event inputs, parameter values in their data inputs are forwarded to the appropriate algorithms, which generate new events and data output as control instructions. The data inputs also include monitored real-time information which allows the dynamic creation of equipment control code adapted to the actual run-time conditions on the shop-floor. Manufacturing features build on the concept that a manufacturing task can be broken down into a sequence of minor basic operations, in this research assembly features (AFs). These features define atomic assembly operations, and by combining and implementing these in the event-driven FB embedded algorithms, automatic code generation is possible. A test case with a virtual robot assembly cell is presented, demonstrating the functionality of the proposed control approach.

  • 11.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Department of Production Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Moore, Philip
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Feature-based control and information framework for adaptive and distributed manufacturing in cyber physical systems2017Inngår i: Journal of manufacturing systems, ISSN 0278-6125, E-ISSN 1878-6642, Vol. 43, s. 305-315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modern distributed manufacturing within Industry 4.0, supported by Cyber Physical Systems (CPSs), offers many promising capabilities regarding effective and flexible manufacturing, but there remain many challenges which may hinder its exploitation fully. One major issue is how to automatically control manufacturing equipment, e.g. industrial robots and CNC-machines, in an adaptive and effective manner. For collaborative sharing and use of distributed and networked manufacturing resources, a coherent, standardised approach for systemised planning and control at different manufacturing system levels and locations is a paramount prerequisite.

    In this paper, the concept of feature-based manufacturing for adaptive equipment control and resource-task matching in distributed and collaborative CPS manufacturing environments is presented. The concept has a product perspective and builds on the combination of product manufacturing features and event-driven Function Blocks (FB) of the IEC 61499 standard. Distributed control is realised through the use of networked and smart FB decision modules, enabling the performance of collaborative run-time manufacturing activities according to actual manufacturing conditions. A feature-based information framework supporting the matching of manufacturing resources and tasks, as well as the feature-FB control concept, and a demonstration with a cyber-physical robot application, are presented.

  • 12.
    Adamson, Göran
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Department of Production Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Moore, Philip
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Feature-based Function Block Control Framework for Manufacturing Equipment in Cloud Environments2018Inngår i: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 57, nr 12, s. 3954-3974Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability to adaptively control manufacturing equipment in cloud environments is becoming increasingly more important. Industry 4.0, supported by Cyber Physical Systems and the concept of on-demand, scalable and pay-for-usage resource-sharing in cloud environments offers many promises regarding effective and flexible manufacturing. For implementing the concept of manufacturing services in a cloud environment, a cloud control approach for the sharing and control of networked manufacturing resources is required. This paper presents a cloud service-based control approach which has a product perspective and builds on the combination of event-driven IEC 61499 Function Blocks and product manufacturing features. Distributed control is realised through the use of a networked control structure of such Function Blocks as decision modules, enabling an adaptive run-time behaviour. The control approach has been developed and implemented as prototype systems for both local and distributed manufacturing scenarios, in both real and virtual applications. An application scenario is presented to demonstrate the applicability of the control approach. In this scenario, Assembly Feature-Function Blocks for adaptive control of robotic assembly tasks have been used.

    Fulltekst (pdf)
    fulltext
  • 13.
    Adell, J.
    et al.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Ulfat, I.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden / Department of Physics, University of Karachi, Karachi, Pakistan.
    Ilver, L.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Sadowski, J.
    Institute of Physics, Polish Academy of Sciences, Warsaw, Poland / MAX-lab, Lund University, Lund, Sweden.
    Karlsson, Krister
    Högskolan i Skövde, Institutionen för vård och natur. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Kanski, J.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Thermal diffusion of Mn through GaAs overlayers on (Ga, Mn)As2011Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 23, nr 8, artikkel-id 085003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermally stimulated diffusion of Mn through thin layers of GaAs has been studied by x-ray photoemission. (Ga, Mn)As samples with 5 at% Mn were capped with 4, 6 and 8 monolayer (ML) GaAs, and Mn diffusing through the GaAs was trapped on the surface by means of amorphous As. It was found that the out-diffusion is completely suppressed for an 8 ML thick GaAs film. The short diffusion length is attributed to an electrostatic barrier formed at the (Ga, Mn)As/GaAs interface.

  • 14.
    Alfredsson, K. Svante
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Biel, Anders
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Salimi, Saeed
    Högskolan i Skövde.
    Shear testing of thick adhesive layers using the ENF-specimen2015Inngår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 62, s. 130-138Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Alfredsson, K. Svante
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gawandi, A. A.
    Center for Composite Materials, University of Delaware, Newark, USA.
    Gillespie, J. W., Jr.
    Center for Composite Materials, University of Delaware, Newark, USA.
    Carlsson, L. A.
    Department of Mechanical Engineering, Florida Atlantic University, Boca Raton, USA.
    Bogetti, T. A.
    Army Research Laboratory, Aberdeen Proving Ground, MD, USA.
    Stress analysis of axially and thermally loaded discontinuous tile core sandwich with and without adhesive filled core gaps2011Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 93, nr 7, s. 1621-1630Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An analytical study is performed to investigate the stress states in an axially and thermally loaded sandwich structure with a discontinuous ceramic tile core. General and simplified models are developed to determine stresses in the constituents of the sandwich structure with and without adhesive in the gaps between adjacent tiles. A general model that allows local bending of the face sheet and a simplified model which assumes uniform through-thickness stress distribution in the face sheets are developed. It is shown that the normal stress in the face sheet decreases when the gap is filled by adhesive, although the tile stress increases. The analytical model shows that normal and shear stresses at the face/core interface can be reduced by filling the gaps between tiles. Filled gaps also elevate the axial stiffness of the structure. Model results are verified by comparison to a previously developed analytical model and finite element analysis. (C) 2011 Elsevier Ltd. All rights reserved.

  • 16.
    Alfredsson, K. Svante
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gawandi, A. A.
    Center for Composite Materials, University of Delaware, Newark, USA.
    Gillespie Jr., J. W.
    Center for Composite Materials, University of Delaware, Newark, USA.
    Carlsson, L. A.
    Department of Mechanical Engineering, Florida Atlantic University, Boca Raton, USA.
    Bogetti, T. A.
    Army Research Laboratory, Aberdeen Proving Ground, USA.
    Flexural analysis of discontinuous tile core sandwich structure2012Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 94, nr 5, s. 1524-1532Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three-point flexure loading of sandwich beams with a core consisting of discrete ceramic tiles (DTSS) is considered. The tile gaps may be bonded or unbonded (open gaps). The analysis utilizes a layer-wise beam theory approach. The general formulation for the displacements and stresses in the face sheets, face/core adhesive layer, and core is derived. Solutions for stresses and displacements of the beam constituents are obtained from finite element formulation based on analytical solution of the face sheet/tile unit cell. The approach is verified by comparison to stress results obtained from ordinary finite element analysis where each layer is modeled discretely. Effects of load introduction and support conditions on the effective flexural stiffness are examined. It is demonstrated that the face sheets experience substantial stress concentrations at the tile joint locations, especially if the gaps are unfilled. Analysis of beam compliance reveals sensitivity to details of load introduction and support conditions, especially when the span length becomes comparable to the tile length.

  • 17.
    Alfredsson, K. Svante
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Stigh, Ulf
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Stability of beam-like fracture mechanics specimens2012Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 89, s. 98-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Test specimens used to determine the interlaminar strength of composites as well as the strength of adhesive layers are known to occasionally suffer from instability. Thus, even though the experiments are performed under controlled load-point displacement, the experiments are terminated prematurely by unstable crack propagation. Often there exists a critical crack length which must be exceeded in order to obtain stable crack propagation. In this paper, a general method to assess the stability of beam-like fracture mechanics specimens is developed. Both systems subjected to a single load and the more general situation with several independent loads are treated. A simple formula is derived for the critical crack length for one-parameter loading. The only parameter necessary as input is the compliance of the un-cracked specimen. For the case of non-proportional loading, stability is determined by studying the eigenvalues of a symmetric matrix. Other findings quantified in the paper are the effect of orthotropy, the influence of a flexible interphase layer and the influence of the compliance of the loading device.

  • 18.
    Alklind Taylor, Anna-Sofia
    et al.
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Backlund, Per
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Johannesson, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Krasniqi, Hanife
    Lebram, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Acceptance of Entertainment Systems in Stroke Rehabilitation2009Inngår i: Proceedings of IADIS Game and Entertainment Technologies 2009 (GET 2009), IADIS Press , 2009, s. 75-83Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Game-based tools for rehabilitation of different types of physical and cognitive impairments are becoming more and more popular. By introducing an element of fun, these systems aim at increasing patients' motivation to train and, from a further perspective, improve recovery rates. There is, however, a question whether such tools will be fully accepted by the intended target group. Earlier work on user acceptance has mainly focused on utility systems, i.e. systems used mainly in the work place. However, people use systems for different reasons and that makes it difficult to apply the same principles on systems with the main purpose to entertain. Serious games have characteristics from both utility and entertainment systems, which makes it interesting to study the acceptance of these kinds of systems. In this study, we have developed a home-based entertainment system for stroke rehabilitation, with focus on rehabilitation of motor impairments. By analysing the gaming behaviour and interview responses of five stroke patients, we investigate factors influencing user acceptance of this specific type of system. The results show that current models of acceptance are not sufficient to fully explain acceptance of serious games in general and serious games for rehabilitation in particular. Besides well-known factors, such as perceived usefulness, perceived ease-of-use and perceived enjoyment, other, more specific, factors also play a vital role in the acceptance of the system.

  • 19.
    Alklind Taylor, Anna-Sofia
    et al.
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Backlund, Per
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Johannesson, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lebram, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gamers against All Odds2009Inngår i: Learning by playing: game-based education system design and development: 4th International Conference on E-Learning and Games, Edutainment 2009, Banff, Canada, August 9-11, 2009: proceedings / [ed] Maiga Chang; Rita Kuo; Kinshuk; Gwo-Dong Chen; Michitaka Hirose, Springer Berlin/Heidelberg, 2009, s. 1-12Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The goal of the project presented in this paper is to enable motor rehabilitation to stroke patients in their home environment and to utilise game enjoyment to achieve frequent training. Stroke patients have an average age above 70 years, which implies that they typically do not belong to a gaming generation. In addition, these patients suffer from motor, and many times cognitive impairments, which make traditional games extremely difficult to use. Nearly all work in this area has been conducted in a clinic environment where it is possible to overcome some of these difficulties by letting professionals assist and guide patients.

    In this paper, we present the challenges faced, the system itself and the result from a study where five patients were equipped with a game console in their homes for five weeks. The focus of this paper is on analysing the gaming behaviour of patients, which includes the amount of time they spent, the type of games they selected and their comments on the gaming experience. The conclusion from this analysis is that their behaviour resembles that of gamers. They spent significant voluntary time, and it has been possible for patients, with no prior experience of computer games, to enjoy gaming in their homes where they had no professional assistance.

  • 20.
    Alklind Taylor, Anna-Sofia
    et al.
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Backlund, Per
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Johannesson, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lebram, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    The Birth of Elinor: A Collaborative Development of a Game Based System for Stroke Rehabilitation2009Inngår i: 2009 Second International Conference in Visualisation / [ed] Ebad Banissi, Muhammad Sarfraz, Farzad Khosrowshahi, John Counsell, Richard Laing, Chris Moore, Andrew J. Cowell, Ming Hou, Gui Yun Tian, Mohammad Dastbaz, Mark Bannatyne, Jian J. Zhang, Vittorio Scarano, Rosario De Chiara, Ugo Erra, Anna Ursyn and Haim Levkowitz, IEEE, 2009, s. 52-60, artikkel-id 5230709Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Elinor is a game based tool for rehabilitation of stroke patients to be used in their home environment. The application is the result of a creative and exploratory development project in which researchers in the serious games area and experts in stroke rehabilitation collaborated in order to develop a motivating, easy to use and relatively inexpensive tool for relearning functions lost due to a stroke. Elinor can be viewed as an integrated system for stroke rehabilitation in that it is both a system, controlled by movements, for training of its primary user group and a system for monitoring the training by medical expertise. In this paper, we will describe the Elinor application itself, the development process and the initial evaluation of it in order to identify implications for serious games.

     

  • 21.
    Allert, Anna-Lena
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    ProduktionsKompetensCentrum - En studie av effekter av projektstöd till tillverkande företag i Skaraborg2013Rapport (Annet vitenskapelig)
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    fulltext
  • 22.
    Allert, Anna-Lena
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Säfsten, Kristina
    School of Engineering, Jönköping University, Jönköping, Sweden.
    Business Support Agencies introducing Lean Production in SMEs - Does it make any difference?2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many SMEs are implementing lean production in collaboration with a business support agency in order to improve their competitiveness. This research investigated whether improvement initiatives had the intended effect in some companies. A questionnaire was answered by employees in 26 SMEs. The result indicated experienced effect concerning leadership, communication and employee commitment, areas considered important for success in improvement initiatives,   and also progress in areas that characterise development towards lean. The result also indicated differences in experienced effect between managerial and non-managerial functions and between companies. 

    Fulltekst (pdf)
    fulltext
  • 23.
    Ambring, Erik
    et al.
    Immersive Learning Gothia Science Park, Kaplansgatan 18, 54134 Skövde, Sweden.
    Dahlin, Carl-Johan
    Immersive Learning Gothia Science Park, Kaplansgatan 18, 54134 Skövde, Sweden.
    Sjöstrand, Erik
    Immersive Learning Gothia Science Park, Kaplansgatan 18, 54134 Skövde, Sweden.
    Håkansson, Peter
    Tidaholms församling, Church of Sweden, Box 93, Norra kungsv. 6, 52222 Tidaholm, Sweden.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Developing the Game Testament: Multiple Perspectives in Serious Game Development2010Inngår i: Proceedings of the IADIS International Conference on Game and Entertainment Technologies: Freiburg, Germany 26-30 July 2010 / [ed] Katherine Blashki, IADIS Press, 2010, s. 35-44Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This article presents the process of creating the game Testament; an action role-playing game for PC which uses the Old Testament as its setting. The game is primarily designed for confirmation education in the Church of Sweden, with the purpose to create interest in the Old Testament. In this paper we describe our experiences with the process of creating a game  where  the  work  has  been  guided  by  three,  in  some  cases,  contradictory  goals:  the  educational  value,  the  source authenticity and the gaming entertainment.  Our  conclusion  is  that  clear  requirements  for  the  entertainment  must  be  created  as  a  counterweight  to  the  practical aspects' requirements, e.g. education and authenticity. To create requirements  for game experience, it can be useful to identify a game genre and find a game that can serve as a template. One consequence of the fact that a specific goal for entertainment and a very clear requirement on content existed was that a number of fundamental contradictions could be identified  (e.g.  narrative,  game  mechanics,  adaptation).  When  these  inconsistencies  were  encountered,  a  suitable approach could be chosen in order to reach a compromise. If an existing game used as a reference wasn't available, it is likely that the entertainment would have suffered for the benefit of the educational aspects and biblical authenticity.

  • 24.
    Amouzgar, Kaveh
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Metamodel Based Multi-Objective Optimization with Finite-Element Applications2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    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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  • 25.
    Amouzgar, Kaveh
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Andersson, Tobias J.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A framework for simulation based multi-objective optimization and knowledge discovery of machining process2018Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 98, nr 9-12, s. 2469-2486Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 26.
    Amouzgar, Kaveh
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Andersson, Tobias J.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Metamodel based multi-objective optimization of a turning process by using finite element simulationManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    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.

  • 27.
    Amouzgar, Kaveh
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Radial basis functions with a priori bias as surrogate models: A comparative study2018Inngår i: Engineering applications of artificial intelligence, ISSN 0952-1976, E-ISSN 1873-6769, Vol. 71, s. 28-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radial basis functions are augmented with a posteriori bias in order to perform robustly when used as metamodels. Recently, it has been proposed that the bias can simply be set a priori by using the normal equation, i.e., the bias becomes the corresponding regression model. In this study, we demonstrate the performance of the suggested approach (RBFpri) with four other well-known metamodeling methods; Kriging, support vector regression, neural network and multivariate adaptive regression. The performance of the five methods is investigated by a comparative study, using 19 mathematical test functions, with five different degrees of dimensionality and sampling size for each function. The performance is evaluated by root mean squared error representing the accuracy, rank error representing the suitability of metamodels when coupled with evolutionary optimization algorithms, training time representing the efficiency and variation of root mean squared error representing the robustness. Furthermore, a rigorous statistical analysis of performance metrics is performed. The results show that the proposed radial basis function with a priori bias achieved the best performance in most of the experiments in terms of all three metrics. When considering the statistical analysis results, the proposed approach again behaved the best, while Kriging was relatively as accurate and support vector regression was almost as fast as RBFpri. The proposed RBF is proven to be the most suitable method in predicting the ranking among pairs of solutions utilized in evolutionary algorithms. Finally, the comparison study is carried out on a real-world engineering optimization problem.

  • 28.
    Amouzgar, Kaveh
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Product Development Department, School of Engineering, Jönköping University, Jönköping, Sweden.
    Strömberg, Niclas
    Department of Mechanical Engineering, School of Science and Technology, University of Örebro, Sweden.
    Radial basis functions as surrogate models with a priori bias in comparison with a posteriori bias2017Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 55, nr 4, s. 1453-1469Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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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  • 29.
    Andersson, Marcus
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Grimm, Henrik
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Simulation Optimization for Industrial Scheduling Using Hybrid Genetic Representation2008Inngår i: Proceedings of the 2008 Winter Simulation Conference / [ed] S. J. Mason, R. R. Hill, L. Mönch, O. Rose, T. Jefferson, J. W. Fowler, IEEE conference proceedings, 2008, s. 2004-2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Simulation modeling has the capability to represent complex real-world systems in details and therefore it is suitable to develop simulation models for generating detailed operation plans to control the shop floor. In the literature, there are two major approaches for tackling the simulation-based scheduling problems, namely dispatching rules and using meta-heuristic search algorithms. The purpose of this paper is to illustrate that there are advantages when these two approaches are combined. More precisely, this paper introduces a novel hybrid genetic representation as a combination of both a partially completed schedule (direct) and the optimal dispatching rules (indirect), for setting the schedules for some critical stages (e.g. bottlenecks) and other non-critical stages respectively. When applied to an industrial case study, this hybrid method has been found to outperform the two common approaches, in terms of finding reasonably good solutions within a shorter time period for most of the complex scheduling scenarios.

  • 30.
    Andersson, Martin
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A bilevel approach to parameter tuning of optimization algorithms using evolutionary computing: Understanding optimization algorithms through optimization2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Most optimization problems found in the real world cannot be solved using analytical methods. For these types of difficult optimization problems, an alternative approach is needed. Metaheuristics are a category of optimization algorithms that do not guarantee that an optimal solution will be found, but instead search for the best solutions using some general heuristics. Metaheuristics have been shown to be effective at finding “good-enough” solutions to a wide variety of difficult problems. Most metaheuristics involve control parameters that can be used to modify how the heuristics perform its search. This is necessary because different problems may require different search strategies to be solved effectively. The control parameters allow for the optimization algorithm to be adapted to the problem at hand. It is, however, difficult to predict what the optimal control parameters are for any given problem. The problem of finding these optimal control parameter values is known as parameter tuning and is the main topic of this thesis. This thesis uses a bilevel optimization approach to solve parameter tuning problems. In this approach, the parameter tuning problem itself is formulated as an optimization problem and solved with an optimization algorithm. The parameter tuning problem formulated as a bilevel optimization problem is challenging because of nonlinear objective functions, interacting variables, multiple local optima, and noise. However, it is in precisely this kind of difficult optimization problem that evolutionary algorithms, which are a subclass of metaheuristics, have been shown to be effective. That is the motivation for using evolutionary algorithms for the upper-level optimization (i.e. tuning algorithm) of the bilevel optimization approach. Solving the parameter tuning problem using a bilevel optimization approach is also computationally expensive, since a complete optimization run has to be completed for every evaluation of a set of control parameter values. It is therefore important that the tuning algorithm be as efficient as possible, so that the parameter tuning problem can be solved to a satisfactory level with relatively few evaluations. Even so, bilevel optimization experiments can take a long time to run on a single computer. There is, however, considerable parallelization potential in the bilevel optimization approach, since many of the optimizations are independent of one another. This thesis has three primary aims: first, to present a bilevel optimization framework and software architecture for parallel parameter tuning; second, to use this framework and software architecture to evaluate and configure evolutionary algorithms as tuners and compare them with other parameter tuning methods; and, finally, to use parameter tuning experiments to gain new insights into and understanding of how optimization algorithms work and how they can used be to their maximum potential. The proposed framework and software architecture have been implemented and deployed in more than one hundred computers running many thousands of parameter tuning experiments for many millions of optimizations. This illustrates that this design and implementation approach can handle large parameter tuning experiments. Two types of evolutionary algorithms, i.e. differential evolution (DE) and a genetic algorithm (GA), have been evaluated as tuners against the parameter tuning algorithm irace. The as pects of algorithm configuration and noise handling for DE and the GA as related to the parameter tuning problem were also investigated. The results indicate that dynamic resampling strategies outperform static resampling strategies. It was also shown that the GA needs an explicit exploration and exploitation strategy in order not become stuck in local optima. The comparison with irace shows that both DE and the GA can significantly outperform it in a variety of different tuning problems.

  • 31.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Towards Optimal Algorithmic Parameters for Simulation-Based Multi-Objective Optimization2016Inngår i: 2016 IEEE Congress on Evolutionary Computation (CEC), New York: IEEE, 2016, s. 5162-5169Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of optimization to solve a simulation-based multi-objective problem produces a set of solutions that provide information about the trade-offs that have to be considered by the decision maker. An incomplete or sub-optimal set of solutions will negatively affect the quality of any subsequent decisions. The parameters that control the search behavior of an optimization algorithm can be used to minimize this risk. However, choosing good parameter settings for a given optimization algorithm and problem combination is difficult. The aim of this paper is to take a step towards optimal parameter settings for optimization of simulation-based problems. Two parameter tuning methods, Latin Hypercube Sampling and Genetic Algorithms, are used to maximize the performance of NSGA-II applied to a simulation-based problem with discrete variables. The strengths and weaknesses of both methods are analyzed. The effect of the number of decision variables and the function budget on the optimal parameter settings is also studied.

  • 32.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Tuning of Multiple Parameter Sets in Evolutionary Algorithms2016Inngår i: GECCO'16: Proceedings of the 2016 genetic and evolutionary computation conference, Association for Computing Machinery (ACM), 2016, s. 533-540Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Evolutionary optimization algorithms typically use one or more parameters that control their behavior. These parameters, which are often kept constant, can be tuned to improve the performance of the algorithm on specific problems. However, past studies have indicated that the performance can be further improved by adapting the parameters during runtime. A limitation of these studies is that they only control, at most, a few parameters, thereby missing potentially beneficial interactions between them. Instead of finding a direct control mechanism, the novel approach in this paper is to use different parameter sets in different stages of an optimization. These multiple parameter sets, which remain static within each stage, are tuned through extensive bi-level optimization experiments that approximate the optimal adaptation of the parameters. The algorithmic performance obtained with tuned multiple parameter sets is compared against that obtained with a single parameter set. For the experiments in this paper, the parameters of NSGA-II are tuned when applied to the ZDT, DTLZ and WFG test problems. The results show that using multiple parameter sets can significantly increase the performance over a single parameter set.

  • 33.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Syberfeldt, Anna
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Parameter tuned CMA-ES on the CEC'15 expensive problems2015Inngår i: Evolutionary Computation, IEEE conference proceedings, 2015, s. 1950-1957Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Evolutionary optimization algorithms have parameters that are used to adapt the search strategy to suit different optimization problems. Selecting the optimal parameter values for a given problem is difficult without a-priori knowledge. Experimental studies can provide this knowledge by finding the best parameter values for a specific set of problems. This knowledge can also be constructed into heuristics (rule-of-thumbs) that can adapt the parameters for the problem. The aim of this paper is to assess the heuristics of the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) optimization algorithm. This is accomplished by tuning CMA-ES parameters so as to maximize its performance on the CEC'15 problems, using a bilevel optimization approach that searches for the optimal parameter values. The optimized parameter values are compared against the parameter values suggested by the heuristics. The difference between specialized and generalized parameter values are also investigated.

    Fulltekst (pdf)
    fulltext
  • 34.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Syberfeldt, Anna
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Parameter Tuning of MOEAs Using a Bilevel Optimization Approach2015Inngår i: Evolutionary Multi-Criterion Optimization: 8th International Conference, EMO 2015, Guimarães, Portugal, March 29 --April 1, 2015. Proceedings, Part I / [ed] António Gaspar-Cunha, Carlos Henggeler Antunes & Carlos Coello Coello, Springer International Publishing Switzerland , 2015, s. 233-247Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of an Evolutionary Algorithm (EA) can be greatly influenced by its parameters. The optimal parameter settings are also not necessarily the same across different problems. Finding the optimal set of parameters is therefore a difficult and often time-consuming task. This paper presents results of parameter tuning experiments on the NSGA-II and NSGA-III algorithms using the ZDT test problems. The aim is to gain new insights on the characteristics of the optimal parameter settings and to study if the parameters impose the same effect on both NSGA-II and NSGA-III. The experiments also aim at testing if the rule of thumb that the mutation probability should be set to one divided by the number of decision variables is a good heuristic on the ZDT problems. A comparison of the performance of NSGA-II and NSGA-III on the ZDT problems is also made.

    Fulltekst (pdf)
    fulltext
  • 35.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Parameter Tuning Evolutionary Algorithms for Runtime versus Cost Trade-off in a Cloud Computing Environment2018Inngår i: Simulation Modelling Practice and Theory, ISSN 1569-190X, Vol. 89, s. 195-205Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The runtime of an evolutionary algorithm can be reduced by increasing the number of parallel evaluations. However, increasing the number of parallel evaluations can also result in wasted computational effort since there is a greater probability of creating solutions that do not contribute to convergence towards the global optimum. A trade-off, therefore, arises between the runtime and computational effort for different levels of parallelization of an evolutionary algorithm.  When the computational effort is translated into cost, the trade-off can be restated as runtime versus cost. This trade-off is particularly relevant for cloud computing environments where the computing resources can be exactly matched to the level of parallelization of the algorithm, and the cost is proportional to the runtime and how many instances that are used. This paper empirically investigates this trade-off for two different evolutionary algorithms, NSGA-II and differential evolution (DE) when applied to multi-objective discrete-event simulation-based (DES) problem. Both generational and steadystate asynchronous versions of both algorithms are included. The approach is to perform parameter tuning on a simplified version of the DES model. A subset of the best configurations from each tuning experiment is then evaluated on a cloud computing platform. The results indicate that, for the included DES problem, the steady-state asynchronous version of each algorithm provides a better runtime versus cost trade-off than the generational versions and that DE outperforms NSGA-II.

  • 36.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A Parallel Computing Software Architecture for the Bilevel Parameter Tuning of Optimization AlgorithmsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Most optimization algorithms extract important algorithmic design decisions as control parameters. This is necessary because different problems can require different search strategies to be solved effectively. The control parameters allow for the optimization algorithm to be adapted to the problem at hand. It is however difficult to predict what the optimal control parameters are for any given problem. Finding these optimal control parameter values is referred to as the parameter tuning problem. One approach of solving the parameter tuning problem is to use a bilevel optimization where the parameter tuning problem itself is formulated as an optimization problem involving algorithmic performance as the objective(s). In this paper, we present a framework and architecture that can be used to solve large-scale parameter tuning problems using a bilevel optimization approach. The proposed framework is used to show that evolutionary algorithms are competitive as tuners against irace which is a state-of-the-art tuning method. Two evolutionary algorithms, differential evaluation (DE) and a genetic algorithm (GA) are evaluated as tuner algorithms using the proposed framework and software architecture. The importance of replicating optimizations and avoiding local optima is also investigated. The architecture is deployed and tested by running millions of optimizations using a computing cluster. The results indicate that the evolutionary algorithms can consistently find better control parameter values than irace. The GA, however, needs to be configured for an explicit exploration and exploitation strategy in order avoid local optima.

  • 37.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bernedixen, Jacob
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    On the Trade-off Between Runtime and Evaluation Efficiency In Evolutionary AlgorithmsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Evolutionary optimization algorithms typically use one or more parameters that control their behavior. These parameters, which are often kept constant, can be tuned to improve the performance of the algorithm on specific problems.  However, past studies have indicated that the performance can be further improved by adapting the parameters during runtime. A limitation of these studies is that they only control, at most, a few parameters, thereby missing potentially beneficial interactions between them. Instead of finding a direct control mechanism, the novel approach in this paper is to use different parameter sets in different stages of an optimization. These multiple parameter sets, which remain static within each stage, are tuned through extensive bi-level optimization experiments that approximate the optimal adaptation of the parameters. The algorithmic performance obtained with tuned multiple parameter sets is compared against that obtained with a single parameter set.  For the experiments in this paper, the parameters of NSGAII are tuned when applied to the ZDT, DTLZ and WFG test problems. The results show that using multiple parameter sets can significantly increase the performance over a single parameter set.

  • 38.
    Andersson, Martin
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Syberfeldt, Anna
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bengtsson, Victor
    Posten AB, Solna, Sweden.
    Evolutionary Simulation Optimization of Personnel Scheduling2014Inngår i: 12th International Industrial Simulation Conference 2014: ISC'2014 / [ed] Amos Ng; Anna Syberfeldt, Eurosis , 2014, s. 61-65Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a simulation-optimization system for personnel scheduling. The system is developed for the Swedish postal services and aims at finding personnel schedules that minimizes both total man hours and the administrative burden of the person responsible for handling schedules. For the optimization, the multi-objective evolutionary algorithm NSGA-II is implemented. The simulation-optimization system is evaluated on a real-world test case and results from the evaluation shows that the algorithm is successful in optimizing the problem.

  • 39.
    Andre, A.
    et al.
    Swerea Sicomp AB, Composite Struct, Mölndal, Sweden / Chalmers, Div Struct Engn, Gothenburg, Sweden.
    Haghani, Reza
    Chalmers, Div Struct Engn, Gothenburg, Sweden.
    Biel, Anders
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Application of fracture mechanics to predict the failure load of adhesive joints used to bond CFRP laminates to steel members2012Inngår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 27, nr 1, s. 331-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of bolted or welded elements to upgrade metallic structures has been a common practice for many years. Moreover, the use of adhesively bonded carbon fiber reinforced polymer (CFRP) laminates, as an alternative method, has attracted a great deal of attention in recent years. One important aspect of the design of adhesive joints used to bond CFRP laminates to steel substrates is the determination of the properties of the CFRP/adhesive/steel interfaces, which have not yet been established in codes or standards. The purpose of this paper is experimentally to determine the fracture properties of the adhesive material and to evaluate the accuracy of numerical methods using this information, in order to predict the strength of adhesive joints in steel members bonded with CFRP laminates. The results from four series of experimental tests are compared with numerical results and discussed in terms of load-bearing capacity and failure modes.

  • 40.
    Andreasson, Rebecca
    et al.
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Lindblom, Jessica
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Thorvald, Peter
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Distributed Cognition in Manufacturing: Collaborative Assembly Work2016Inngår i: Advances in Manufacturing Technology XXX / [ed] Yee Mey Goh, Keith Case, IOS Press, 2016, s. 243-248Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 41.
    Andreasson, Rebecca
    et al.
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Lindblom, Jessica
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Thorvald, Peter
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Interruptions in the wild: portraying the handling of interruptions in manufacturing from a distributed cognition lens2017Inngår i: Cognition, Technology & Work, ISSN 1435-5558, E-ISSN 1435-5566, Vol. 19, nr 1, s. 85-108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a study examining interruptionsin the wild by portraying the handling of interruptionsin manufacturing from a distributed cognitionlens. By studying how interruptions occur and are handledin the daily activities of a work team at a large foundry forcasting heavy diesel engines, we highlight situations whenthe propagation, transformation, and representation ofinformation are not supported by prescribed work processesand propose recommendations for how this can beamended. The study was conducted by several visits to theaforementioned factory with cognitive ethnography as thebasis for the data collection. The focus was on identifyinginterruptions and analysing these through a distributedcognition framework as an initial step towards studyinginterruptions in a manufacturing environment. The keyfindings include the identification of three, previouslyundefined, types of interruptions and the conclusion thatinterruptions do indeed affect the distributed workload ofthe socio-technical system and thus the overall productionperformance at the casting line.

    Fulltekst (pdf)
    fulltext
  • 42.
    Andreasson, Rebecca
    et al.
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi. Department of Information Technology, Visual Information and Interaction, Uppsala University, Uppsala, Sweden.
    Lindblom, Jessica
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Thorvald, Peter
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Tool use and collaborative work of dock assembly in practice2017Inngår i: Production & Manufacturing Research, ISSN 2169-3277, Vol. 5, nr 1, s. 164-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to deepen the understanding of the intrinsic interactions andinterplay between humans, tools, and environment from a systemsperspective, research in the wild (RITW) approaches have gainedtraction during recent decades as they provide a higher ecologicalvalidity of findings. This paper presents a RITW study, investigatinghow assembly, in this case dock assembly of forwarders, was donein practice. As our theoretical foundation, we used the framework ofdistributed cognition, which is one of the main pillars of RITW. Thefindings are presented in narrative form, describing and highlightingthat the workers achieve an efficient production outcome by beingintegral parts of the whole production process and doing so throughcoordination of activities benefitting the shared goal of the distributedsocio-technical system.

    Fulltekst (pdf)
    fulltext
  • 43.
    Andreasson, Rebecca
    et al.
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Lindblom, Jessica
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Thorvald, Peter
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Towards an increased degree of usability work in organizations2015Inngår i: Procedia Manufacturing, ISSN 2351-9789, Vol. 3, s. 5739-5746Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is widely recognized that there is a substantial gap between usability research and practice where UCD approaches are rarelyapplied in practice due to arguments regarding the intricate nature of its methods and techniques. This paper presents an actionresearch study designed to investigate and analyze the potentials for an increased degree of UCD activities in the earlydevelopment phases of advanced information systems technology. The results demonstrate that there is a large interest inusability but that organizational priority and competence is often lacking. Instead one relies heavily on questionable conceptssuch as „trained professionals‟ to excuse the low effort towards usability. Based on the results, six recommendations forimproved usability work in R&D organizations are presented, focusing on the importance of prioritization of, and education inusability work.

  • 44.
    Arrieta, Aitor
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    FB-Environment in Wise-Shop Floor: Algorithm parser and code generation2012Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [en]

    IEC (International Electrotechnical Commission) is the authority that publishes different standards in the  fields  of  electrical  and  electronics  engineering,  to  be  used  internationally.  In  the  area  of manufacturing, it has demanded a new standard to fulfil better solutions of dynamic requirements. The  IEC  61499  redacted  by  IEC  offers  interoperability,  portability,  configurability  and  distributed control applications for manufacturing processes. However, this standard is not a replacement of IEC 61131-3,  one  of  the  most  used  standards  in  industry;  instead,  it  is  a  complement  of  it.  The  basic software units of IEC 61499 are named Function Blocks (FBs), which can be described as blocks that encapsulate functionality. By combining FBs together, it is possible to solve complex problems.   The  objective  of  this  project  (in  close  cooperation  with  another  project)  is  to  develop  a  software environment in Java language. It follows the requirements of IEC 61499, and implement a Function Block  designer  and  a  runtime  execution  environment,  as  a  part  of  an  existing  Wise-ShopFloor framework. The scope of this project covers:     FB  algorithm  editor:  Each  FB  has  one  or  more  algorithms,  which  can  be  defined  in  the algorithm editor using IEC 61131-3 or Java.     FB serialization: Opening and saving the configuration of FBs in Java Class file is one of the tasks  of  this  project.  As  soon  as  the  configuration  is  saved,  the  Java  code  of  FB  can  be generated. Java code is generated because compiled Java allows execution of FB. Saving in Java  Class  file  permits  portability,  i.e.  the  saved  configuration  can  be  opened  in  any  JVM system, and vice versa.      Case study: A simulation of an assembly station using an ABB IRB 140 robot is studied and implemented using the runtime simulator of the Java platform, in which some basic FBs have been also created in a library. This project also includes: (1) implementation of user interface and (2) FB serialization in XML. It  is  anticipated  that  the  developed  environment  will  be  able  to  save  and  open  FBs  configurations either in XML or in Java Class, following the specification of IEC 61499. It will allow portability and reusability.  Because  of  the  portability,  the  so-designed  FBs  can  be  validated  using  another  FB environment such as FBDK (Function Block Development Kit).

    Fulltekst (pdf)
    Thesis_Aitor_Arrieta
  • 45.
    Aryasetiawan, F.
    et al.
    Department of Physics, Division of Mathematical Physics, Lund University, Lund, Sweden.
    Karlsson, Krister
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Miyake, T.
    CD-FMat, AIST, Tsukuba, Japan / ESICMM, National Institute for Materials Science, Tsukuba, Japan.
    Green's function theory of orbital magnetic moment of interacting electrons in solids2016Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 93, nr 16, artikkel-id 161104(R)Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Aryasetiawan, F.
    et al.
    Chiba University, Japan.
    Sakuma, R.
    Chiba University, Japan.
    Karlsson, Krister
    Högskolan i Skövde, Institutionen för vård och natur. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    GW approximation with self-screening correction2012Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 3, s. 035106-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The GW approximation takes into account electrostatic self-interaction contained in the Hartree potential through the exchange potential. However, it has been known for a long time that the approximation contains self-screening error, as is evident in the case of the hydrogen atom. When applied to the hydrogen atom, the GW approximation does not yield the exact result for the electron removal spectra because of the presence of self-screening: the hole left behind is erroneously screened by the only electron in the system that is no longer present. We present a scheme to take into account self-screening and show that the removal of self-screening is equivalent to including exchange diagrams, as far as self-screening is concerned. The scheme is tested on a model hydrogen dimer and it is shown that the scheme yields the exact result to second order in (Uο-Uι)/2t, where Uο andare, respectively, the on-site and off-site Hubbard interaction parameters and t is the hopping parameter.

  • 47.
    Aryasetiawan, Ferdi
    et al.
    Department of Physics, Division of Mathematical Physics, Lund University, Lund, Sweden.
    Karlsson, Krister
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Modern theory of orbital magnetic moment in solids2019Inngår i: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 128, s. 87-108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The magnetic moment in a solid is usually associated with the electron spins but there is an additional contribution due to the orbital motion of the electrons. For a finite system such as an atom or molecule the orbital moment can be readily calculated. However, for a periodic system the formula used for finite systems becomes ill-defined due to the presence of the position operator. In the last decade a modern theory of orbital magnetization that allows for a rigorous calculation of the magnetic moment of periodic crystals has been developed. This article provides a survey of the theoretical development of this new topic as well as recent, albeit a few, applications of the new formula to real materials. Although the original theory was worked out for non-interacting systems, there has been recent progress in the theory of orbital magnetic moment of interacting electrons in solids. To include the effects of electron-electron interactions two approaches have been proposed, one based on current spin density functional theory and another on the many-body Green's function method. The two approaches are very different but both methods provide convenient yet rigorous means of including the effects of exchange and correlations beyond the commonly used local density approximation of density functional theory.

  • 48.
    Aslam, Tehseen
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Analysis of manufacturing supply chains using system dynamics and multi-objective optimization2013Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Supply chains are in general complex networks composed of autonomous entities whereby multiple performance measures in different levels, which in most cases are in conflict with each other, have to be taken into account. Hence, due to the multiple performance measures, supply chain decision making is much more complex than treating it as a single objective optimization problem. Thus, the aim of the doctoral thesis is to address the supply chain optimization problem within a truly Pareto-based multi-objective context and utilize knowledge extraction techniques to extract valuable and useful information from the Pareto optimal solutions. By knowledge extraction, it means to detect hidden interrelationships between the Pareto solutions, identify common properties and characteristics of the Pareto solutions as well as discover concealed structures in the Pareto optimal data set in order to support managers in their decision making. This aim is addressed through the SBO-framework where the simulation methodology is based on system dynamics (SD) and the optimization utilizes multi-objective optimization (MOO). In order to connect the SD and MOO software, this doctoral thesis introduced a novel SD and MOO interface application which allow the modeling and optimization applications to interact. Additionally, this thesis work also presents a novel SD-MOO methodology that addresses the issue of curse off dimensionality in MOO for higher dimensional problems and with the aim to execute supply chain SD-MOO in a computationally cost efficient way, in terms of convergence, solution intensification and accuracy of obtaining the Pareto-optimal front for complex supply chain problems. In order to detect evident and hidden structures, characteristics and properties of the Pareto-optimal solutions, this work utilizes Parallel Coordinates, Clustering and Innovization, which are three different types of tools for post-optimal analysis and facilitators of discovering and retrieving knowledge from the Pareto-optimal set. The developed SD-MOO interface and methodology are then verified and validated through two academic case studies and a real-world industrial application case study. While not all the insights generated in these application studies can be generalized for other supply-chain systems, the analysis results provide strong indications that the methodology and techniques introduced in this thesis are capable to generate knowledge to support academic SCM research and real-world SCM decision making, which to our knowledge cannot be performed by other methods.

    Fulltekst (pdf)
    Analysis of manufacturing supply chains using system dynamics and multi-objective optimization
  • 49.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hedenstierna, Philip
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Multi-objective Optimisation in Manufacturing Supply Chain Systems Design: A Comprehensive Survey and New Directions2011Inngår i: Multi-objective Evolutionary Optimisation for Product Design and Manufacturing / [ed] Lihui Wang, Amos H. C. Ng, Kalyanmoy Deb, Springer London, 2011, s. 35-70Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Research regarding supply chain optimisation has been performed for a long time. However, it is only in the last decade that the research community has started to investigate multi-objective optimisation for supply chains. Supply chains are in general complex networks composed of autonomous entities whereby multiple performance measures in different levels, which in most cases are in conflict with each other, have to be taken into account. In this chapter, we present a comprehensive literature review of existing multi-objective optimisation applications, both analytical-based and simulation-based, in supply chain management publications. Later on in the chapter, we identify the needs of an integration of multi-objective optimisation and system dynamics models, and present a case study on how such kind of integration can be applied for the investigation of bullwhip effects in a supply chain.

  • 50.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Ng, Amos
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Agent-based Simulation and Simulation-based Optimisation for Supply Chain Management2010Inngår i: Enterprise Networks and Logistics for Agile Manufacturing / [ed] Lihui Wang & S. C. Lenny Koh, Springer London, 2010, s. 227-247Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Agent-based simulation (ABS) represents a paradigm in the modelling and simulation of complex and dynamic systems distributed in time and space. Since manufacturing and logistics operations are characterised by distributed activities as well as decision making - in both time and in space - and can be regarded as complex, the ABS approach is highly appropriate for these types of systems. The aim of this chapter is to present a new framework of applying ABS and simulation-based optimisation techniques to supply chain management, which considers the entities (supplier, manufacturer, distributor and retailer) in the supply chain as intelligent agents in a simulation. This chapter also gives an outline on how these agents pursue their local objectives/goals as well as how they react and interact with each other to achieve a more holistic objective(s)/goal(s).

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