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  • 101.
    Berndtsson, Mikael
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Admyre, Marco
    RuleCore, Sweden.
    Strand, Mattias
    University of Skövde, School of Engineering Science. University of Skövde, The Informatics Research Centre.
    A Fleet Management System Based on Complex Event Processing2014In: DSS 2.0 – Supporting Decision Making with New Technologies / [ed] Gloria Phillips-Wren, Sven Carlsson, Ana Respício, Patrick Brézillon, IOS Press, 2014, p. 241-252Conference paper (Refereed)
  • 102.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Automated Bottleneck Analysis of Production Systems: Increasing the applicability of simulation-based multi-objective optimization for bottleneck analysis within industry2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Manufacturing companies constantly need to explore new management strategies and new methods to increase the efficiency of their production systems and retain their competitiveness. It is of paramount importance to develop new bottleneck analysis methods that can identify the factors that impede the overall performance of their productionsystems so that the optimal improvement actions can be performed. Many of the bottleneck-related research methods developed in the last two decades are aimed mainly at detecting bottlenecks. Due to their sole reliance on historical data and lackof any predictive capability, they are less useful for evaluating the effect of bottleneck improvements.

    There is an urgent need for an efficient and accurate method of pinpointing bottlenecks, identifying the correct improvement actions and the order in which these should be carried out, and evaluating their effects on the overall system performance. SCORE (simulation-based constraint removal) is a novel method that uses simulation based multi-objective optimization to analyze bottlenecks. By innovatively formulating bottleneck analysis as a multi-objective optimization problem and using simulation to evaluate the effects of various combinations of improvements, all attainable, maximum throughput levels of the production system can be sought through a single optimization run. Additionally, post-optimality frequency analysis of the Pareto-optimal solutions can generate a rank order of the attributes of the resources required to achieve the target throughput levels. However, in its original compilation, SCORE has a very high computational cost, especially when the simulation model is complex with a large number of decision variables. Some tedious manual setup of the simulation based optimization is also needed, which restricts its applicability within industry, despite its huge potential. Furthermore, the accuracy of SCORE in terms of convergence in optimization theory and correctness of identifying the optimal improvement actions has not been evaluated scientifically.

    Building on previous SCORE research, the aim of this work is to develop an effective method of automated, accurate bottleneck identification and improvement analysis that can be applied in industry.

    The contributions of this thesis work include:

    (1) implementation of a versatile representation in terms of multiple-choice set variables and a corresponding constraint repair strategy into evolutionary multi-objective optimization algorithms;

    (2) introduction of a novel technique that combines variable screening enabled initializationof population and variable-wise genetic operators to support a more efficient search process;

    (3) development of an automated setup for SCORE to avoid the tedious manual creation of optimization variables and objectives;

    (4) the use of ranking distance metrics to quantify and visualize the convergence and accuracy of the bottleneck ranking generated by SCORE.

    All these contributions have been demonstrated and evaluated through extensive experiments on scalable benchmark simulation models as well as several large-scale simulation models for real-world improvement projects in the automotive industry.

    The promising results have proved that, when augmented with the techniques proposed in this thesis, the SCORE method can offer real benefits to manufacturing companies by optimizing their production systems.

  • 103.
    Bernedixen, Jacob
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Multiple Choice Sets and Manhattan Distance Based Equality Constraint Handling for Production Systems OptimizationIn: Computers & Operations Research, ISSN 0305-0548, E-ISSN 1873-765XArticle in journal (Refereed)
    Abstract [en]

    Many simulation-based optimization packages provide powerful algorithms to solve industrialproblems. But most of them fail to oer their users the techniques they needto eectively handle multiple-choice problems involving a large set of decision variableswith mixed types (continuous, discrete and combinatorial) and problems that are highlyconstrained (e.g., with many equality constraints). Yet such issues are found in manyreal-world production system design and improvement problems. Thus, this paper introducesa method to eectively embed multiple choice sets and Manhattan-distancebasedconstraint handling into multi-objective optimization algorithms like NSGA-II andNSGA-III. This paper illustrates and evaluates how these two techniques have been appliedtogether to solve optimal workload, buer and workforce allocation problems. Anexample follows, showing their application to a complex production system improvementproblem at an automotive manufacturer.

  • 104.
    Bernedixen, Jacob
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Practical Production Systems Optimization Using Multiple-Choice Sets and Manhattan Distance based Constraints Handling2014In: Industrial Simulation Conference, Skövde, June 11-13, 2014, 2014, p. 97-103Conference paper (Refereed)
    Abstract [en]

    Many simulation-based optimization packages provide powerful algorithms to solve large-scale system problems. But most of them fall short to offer their users the techniques to effectively handle decision variables that are of multiple-choice type, as well as equality constraints, which can be found in many real-world industrial system design and improvement problems. Hence, this paper introduces how multiple choice sets and Manhattan-distance-based constraint handling can be effectively embedded into a meta-heuristic algorithm for simulation-based optimization. How these two techniques have been applied together to make the improvement of a complex production system, provided by an automotive manufacturer, possible will also be presented.

  • 105.
    Bernedixen, Jacob
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Engineering Science.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bandaru, Sunith
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    On the convergence of stochastic simulation-based multi-objective optimization for bottleneck identificationIn: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588XArticle in journal (Refereed)
    Abstract [en]

    By innovatively formulating a bottleneck identication problem into a bi-objective optimization,simulation-based multi-objective optimization (SMO) can be eectively used as a new method for gen-eral production systems improvement. In a single optimization run, all attainable, maximum throughputlevels of the system can be sought through various optimal combinations of improvement changes ofthe resources. Additionally, the post-optimality frequency analysis on the Pareto-optimal solutions cangenerate a rank order of the attributes of the resources required to achieve the target throughput levels.Observing that existing research mainly put emphasis on measuring the convergence of the optimizationin the objective space, leaving no information on when the solutions in the decision space have convergedand stabilized, this paper represents the rst eort in increasing the knowledge about the convergence ofSMO for the rank ordering in the context of bottleneck analysis. By customizing the Spearman's footruledistance and Kendall's tau, this paper presents how these metrics can be used eectively to provide thedesired visual aid in determining the convergence of bottleneck ranking, hence can assist the user todetermine correctly the terminating condition of the optimization process. It illustrates and evaluatesthe convergence of the SMO for bottleneck analysis on a set of scalable benchmark models as well as twoindustrial simulation models. The results have shed promising direction of applying these new metrics tocomplex, real-world applications.

  • 106.
    Bernedixen, Jacob
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bandaru, Sunith
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Variables Screening Enabled Multi-Objective Optimization for Bottleneck Analysis of Production SystemsManuscript (preprint) (Other academic)
    Abstract [en]

    Bottleneck analysis can be defined as the process that includes both bottleneck identification and improvement. In the literature most of the proposed bottleneck-related methods address mainly bottleneck detection. By innovatively formulating a bottleneck analysis into a bi-objective optimization method, recent research has shown that all attainable, maximized TH of a production system, through various combinations of improvement changes of the resources, can be sought in a single optimization run. Nevertheless, when applied to simulation-based evaluation, such a bi-objective optimization is computationally expensive especially when the simulation model is complex and/or with a large amount of decision variables representing the improvement actions. The aim of this paper is therefore to introduce a novel variables screening enabled bi-objective optimization that is customized for bottleneck analysis of production systems. By using the Sequential Bifurcation screening technique which is particularly suitable for large-scale simulation models, fewer simulation runs are required to find the most influenacing factors in a simulation model. With the knowledge of these input variables, the bi-objective optimization used in the bottleneck analysis can customize the genetic operators on these variables individually according to their rank of main effects with the target to speed up the entire optimization process. The screening-enabled algorithm is then applied to a set of experiments designed to evaluate how well it performs when the number of variables increases is a scalable, benchmark model, as well as two real-world industrial-scale simulation models found in the automotive industry. The results have illustrated the promising direction of incorporating the knowledge of influencing variables and variable-wise genetic operators into a multi-objective optimization algorithm for bottleneck analysis.

  • 107.
    Bernedixen, Jacob
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Engineering Science.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Gothenburg, Sweden.
    Antonsson, Tobias
    Volvo Car Corporation, Gothenburg, Sweden.
    Simulation-based multi-objective bottleneck improvement: Towards an automated toolset for industry2015In: Proceedings of the 2015 Winter Simulation Conference / [ed] L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti, Press Piscataway, NJ: IEEE Press, 2015, p. 2183-2194Conference paper (Refereed)
    Abstract [en]

    Manufacturing companies of today are under pressure to run their production most efficiently in order to sustain their competitiveness. Manufacturing systems usually have bottlenecks that impede their performance, and finding the causes of these constraints, or even identifying their locations, is not a straightforward task. SCORE (Simulation-based COnstraint REmoval) is a promising method for detecting and ranking bottlenecks of production systems, that utilizes simulation-based multi-objective optimization (SMO). However, formulating a real-world, large-scale industrial bottleneck analysis problem into a SMO problem using the SCORE-method manually include tedious and error-prone tasks that may prohibit manufacturing companies to benefit from it. This paper presents how the greater part of the manual tasks can be automated by introducing a new, generic way of defining improvements of production systems and illustrates how the simplified application of SCORE can assist manufacturing companies in identifying their production constraints.

  • 108.
    Biel, Anders
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Alfredsson, K. Svante
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Carlberger, Thomas
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Adhesive Tapes; Cohesive Laws for a Soft Layer2014In: Procedia Materials Science, ISSN 2211-8128, Vol. 3, p. 1389-1393Article in journal (Refereed)
    Abstract [en]

    For adhesive tapes, the strain before fracture often exceeds 500%. Although the maximum stresses are quite modest the high strains to fracture result in impressive fracture energy. Due to hydrostatic stress the fracture process often starts by nucleation of microscopic cracks inside the layer. The final crack path is usually close to one of the adherends.

    Repeated experiments are performed both with DCB-specimens and butt-joints. The used adhesive tape is an acrylic foam tape with a thickness of 1.1 mm and a width of 19 mm. The geometry of the specimen is adapted to the properties of the soft layer. For the DCB-specimen this implies that the length of the specimen is about 1 m. The evaluated cohesive laws from the DCB- specimens give a fracture energy of 2 kN/m and a maximum stress about 0.5 MPa. For the butt-joints, the evaluated cohesive law corresponds well to the results from the DCB-experiments. However, the strain to fracture is slightly smaller. The stress in these specimens is distributed over a larger area and a nucleated crack rapidly crosses the load bearing area and fails the joint prematurely. For both kinds of experiments the evaluated cohesive laws show a small linear part. After this part there is an almost linear strain-hardening phase until fracture.

  • 109.
    Biel, Anders
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Chaudhry, Mobina
    Institute of Biomedicine, University of Gothenburg, Göteborg, Sweden.
    Gustafsson, Stefan
    Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nygren, Håkan
    Institute of Biomedicine, University of Gothenburg, Göteborg, Sweden.
    The use of MgO-paste as a biodegradeable bone cement2016In: Materials Today: Proceedings, E-ISSN 2214-7853, Vol. 3, no 2, p. 556-561Article in journal (Refereed)
    Abstract [en]

    The use of MgO-paste as bone cement was tested on titanium cylinders implanted into rat tibia. The evaluation of bone healingwas made with the retention force (pull-out) test, light microscopy and ESEM/ EDX. Preimplantation of the MgO-paste into drillperforations of rat tibia increased the retention of the titanium implant 6-fold. The error was expressed as the 95% confidenceinterval of means (n=10 bones in each group). The observed difference between 3.46+/-0.71 N/mm2 for Ti-cylinders implantedwith MgO-paste and 0.56+/-0.26 N/mm2 for Ti-cylinders implanted directly into the bone, is statistically significant (p<0.01).The increase of retention force, caused by MgO is parallel to an increased thickness of the compact bone surrounding the implantand closer contact between bone and implant.Histological examination of the implant-related bone showed that the MgO-induced bone growth is mediated by the formation ofa bone-inducing matrix. The matrix contains organic substance, most likely proteins.

  • 110.
    Biel, Anders
    et al.
    Department of Wind Energy, Technical University of Denmark, Roskilde, Denmark.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Cohesive zone modelling of nucleation, growth and coalesce of cavities2017In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 204, no 2, p. 159-174Article in journal (Refereed)
    Abstract [en]

    The stress-deformation relation i.e. cohesive law representing the fracture process in an almost incompressible adhesive tape is measured using the double cantilever beam specimen. As in many ductile materials, the fracture process of the tape involves nucleation, growth and coalesce of cavities. This process is studied carefully by exploiting the transparency of the used materials and the inherent stability of the specimen configuration. Utilising the path independence of the J -integral, the cohesive law is measured. The law is compared to the results of butt-joint tests. The law contains two stress peaks—the first is associated with nucleation of cavities at a stress level conforming to predictions of void nucleation in rubber elasticity. The second stress peak is associated with fracture of stretched walls between fully-grown cavities. After this second peak, a macroscopic crack is formed. The tape suffers at this stage an engineering strain of about 800%. A numerical analysis with the determined cohesive law recreates the global specimen behaviour.

  • 111.
    Biel, Anders
    et al.
    Karlstad University.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Comparison of J-integral methods to experimentally determine cohesive laws in shear for adhesives2019In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 94, p. 64-75Article in journal (Refereed)
    Abstract [en]

    High-quality simulation methods demand accurate material models. In simulations an adhesive can be represented by a cohesive layer. A cohesive layer model utilizes a cohesive law to represent the homogenized mechanical behaviour of a layer with a thickness. In the current paper we use three experimental methods to measure the cohesive law in shear using the ENF-specimen; one of the methods is novel and is also useful for evaluation of experiments with the ELS-specimen. Two sets of experiments are performed, one with elastic substrates and one with plastically deforming substrates. Each experiment is evaluated using all three methods. The evaluation shows that all methods provide reasonable data; the results are similar if the substrates are elastic. With smaller specimens, the substrates deform plastically and one of the methods is identified as the most accurate.

  • 112.
    Biel, Anders
    et al.
    Department of Wind Energy, Technical University of Denmark.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Measurement of tensile properties of fibres using a DCB-specimen2015In: 20th International Conference on Composite Materials: Copenhagen, 19-24th July 2015 / [ed] Ole Thybo Thomsen, Bent F. Sørensen, Christian Berggreen, 2015Conference paper (Refereed)
    Abstract [en]

    Constitutive data are needed at extreme strains to increase the understanding of fracture processes. Ordinary tensile tests ends prematurely due to localization and large amounts of elastic energy stored in the specimens prior to fracture. A novel method is proposed to perform tensile tests using a double cantilever beam specimen. To verify the method a large specimen is developed and tested. Similar results are achieved with the present method as with more standardized methods giving confidence in the method. The specimen should be possible to minimise to provide data with small specimens.

  • 113.
    Biel, Anders
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Strength and toughness in shear of constrained layers2018In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 138, p. 50-63Article in journal (Refereed)
    Abstract [en]

    Confined layers may fracture in shear. This occurs, for example in adhesive joints and composite materials. A common mechanism for shear fracture is the formation of shear hackles associated with an expansion of the layer. This makes shear toughness and strength depend on the constraint of the expansion. By constraining the expansion using external loading in experiments, the expansion is reduced but not totally inhibited. The experiments are evaluated using the path independent properties of the J-integral. It is shown that the shear toughness increases for the more constrained case. Thus, from a strength analysis perspective, ignoring the expansion leads to a conservative estimate of the fracture properties. Extrapolation of the evaluated properties to totally inhibited expansions gives the traction separation relation and the fracture toughness for a layer in simple shear.

  • 114.
    Billing, Erik
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Lamb, Maurice
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Digital Human Modelling in Action2019In: Proceedings of the 15th SweCog Conference / [ed] Linus Holm, Erik Billing, Skövde: University of Skövde , 2019, p. 25-28Conference paper (Refereed)
  • 115.
    Binnberg, Dennis
    et al.
    University of Skövde, School of Engineering Science.
    Johansson, Viktor
    University of Skövde, School of Engineering Science.
    Virtual Commissioning: Emulation of a production cell2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Volvo is continually updating and replacing their equipment and want to investigate the possibility to shorten the time it takes to implement changes and shorten the time in commissioning projects. The use of an emulation model of a production cell can shorten the commissioning time since the equipment and sequence of the cell can be thoroughly tested before implementation. Volvo also wants to investigate the possibility to validate equipment using emulation. The main objectives are to find an emulation software that suits Volvo’s needs and build an emulation model of an actual production cell at Volvo called G750. A literature review was performed in which the authors gained knowledge about virtual commissioning, simulation and emulation and the usage of these. A market survey was conducted in order to find emulation software that could handle Volvo’s complex production equipment consisting of ABB robots and Siemens PLC. A method for building emulation models of existing production equipment was found during the literature review. The software used to build the emulation model was Simumatik3D. Other software used to make the model as realistic as possible includes RobotStudio, WinCC and PLCSIM. The emulation model handles approximately 350 inputs and outputs. When the emulation model was finished experiments were conducted in order to answer research questions and to reach the main objectives. The experiments validate that the emulation model is representative of the real production cell regarding programming, fail scenarios and movement.

  • 116.
    Birtic, Martin
    University of Skövde, School of Engineering Science.
    An Open Data Model for Emulation Models of Industrial Components2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Emulation is a technology, historically mostly used for virtual commissioning of automated industrial systems, and operator training. Trends show that new areas for deployment are being investigated. One way to broaden the scope of emulation technology is to increase emulation detail level. The University of Skövde conduct research within emulation technology, and are developing a higher detail level emulation platform performing  on component level. For transparent and systematic development of component models on this level, an open, extensible, and flexible data model for emulation models of industrial components is wanted. This thesis is contributing to this endeavour by developing a first draft of such a data model. A demonstration is also conducted by implementing a few components into the developing emulation environment, using XML as file format. An iterative "design and creation" methodology was used to develop and implement an object oriented data model. A selected set of industrial components were used to develop and demonstrate the data model, and the final result is visually represented as a class diagram together with explanatory documentation. Using the methodology and data modelling strategy used in this thesis, systematic and transparent development of emulation models on component level is possible in an extensible and flexible manner.

  • 117.
    Birtic, Martin
    University of Skövde, School of Engineering Science.
    SUGGESTIONS TO CONSIDER WHEN ENGAGING IN THE PROCESS OF DEVELOPING A SYSTEM DYNAMICS MODEL FOR FREQUENT ATTENDERS IN HEALTHCARE2019Independent thesis Advanced level (degree of Master (One Year)), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Healthcare systems face many challenges that prevent them from reaching their full potential. Overcoming these challenges can be very difficult in part because of their complexity. Predicting all the possible effects that improvement attempts may create is difficult and high-quality decision support material is difficult to obtain. System dynamics modeling and simulation is a technology that has been applied for some time within the healthcare domain in order to assist the decision-making process. This technology has gained increased interest in the domain over the past decade. This project analyses the application of system dynamics modeling to a specific problem in the healthcare sector, namely that of frequent attenders to the emergency department. A literature review is performed to extract suggestions that could be considered when engaged in the process of developing a system dynamics model for managing frequent attenders in healthcare. It has been found that the research on frequent attenders and their management is very heterogeneous and ambiguous making it difficult to draw strong conclusions about the effectiveness of different management strategies. Model builders are forced to turn to other sources for model data. It is also found that system dynamics modeling of frequent attenders has not yet been done. This situation led to the expansion of the search scope to include related modeling research as the basis for suggestion extraction. 65 suggestions are extracted into three broad categories with the limitation of not being strictly specific to the modeling of frequent attenders, but have a more general nature. And although their value is not evaluated, it is hoped that they could contribute as inspiration to certain system dynamics model development endeavors.

  • 118.
    Björkenstam, Staffan
    et al.
    Geometry and Motion Planning group, Fraunhofer-Chalmers Center, Göteborg, Sweden.
    Nyström, Johan
    Geometry and Motion Planning group, Fraunhofer-Chalmers Center, Göteborg, Sweden.
    Carlson, Johan S.
    Geometry and Motion Planning group, Fraunhofer-Chalmers Center, Göteborg, Sweden.
    Roller, Michael
    Department of Mathematical Methods in Dynamics and Durability, Fraunhofer Institute for Industrial Mathematics, Kaiserslautern, Germany.
    Linn, Joachim
    Department of Mathematical Methods in Dynamics and Durability, Fraunhofer Institute for Industrial Mathematics, Kaiserslautern, Germany.
    Hanson, Lars
    Scania AB, Södertälje, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Leyendecker, Sigrid
    Chair of Applied Dynamics, University of Erlangen-Nuremberg, Germany.
    A framework for motion planning of digital humans using discrete mechanics and optimal control2017In: Proceedings of the 5th International Digital Human Modeling Symposium / [ed] Sascha Wischniewski & Thomas Alexander, Federal Institute for Occupational Safety and Health , 2017, p. 64-71Conference paper (Refereed)
    Abstract [en]

    In this paper we present a framework for digital human modelling using discrete mechanics and optimal control. Discrete mechanics is particularly well suited for modelling the dynamics of constrained mechanical systems, which is almost always the case when considering complex human models interacting with the environment. We demonstrate that, by using recently developed recursive dynamics algorithms, we are able to efficiently use discrete mechanics in direct optimal control methods to plan for complex motions. Besides a proper mechanical model, an appropriate objective function is paramount to achieve realistic motions as a solution to an optimal control problem. Hence, several different objective functions, such as for example minimum time or minimum applied torque over the joints, are compared, and the resulting motions are analyzed and evaluated. To further improve the model, we include basic muscular models for the muscles of the shoulder, arm and wrist, and examine how this affects the motions.

  • 119.
    Blomé, Mikael
    et al.
    Lunds Universitet.
    Dukic, Tania
    Chalmers.
    Hanson, Lars
    Lunds Universitet.
    Högberg, Dan
    University of Skövde, School of Engineering Science.
    Web-Based Protocol for Human Simulation Process and Documentation2003Conference paper (Other academic)
  • 120.
    Blåder, Philip
    University of Skövde, School of Engineering Science. philipblader@hotmail.com.
    Bestående deformation av aluminiumhus vid presspassning2018Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The deformation field of an aluminum housing that forms a press joint together with a ring wheel is analyzed in this study. The reason for the study is to get a better idea of the impact of interference fit on the aluminum housing using the Finita element method and practical measurement. Volvo Cars in Skövde asks for a method that can initially verify or dementiate deformations that may mean that the tolerances of the drawing are not obtained. The study will also provide an evaluation if the Finita element method is applicable to capture changes in the detail without confirmation of practical measurement.

    The analysis of the deformation field is performed with the Abaqus software, where the model's relevance is compared to practical measurement using a coordinate measuring machine and 3D scanner. The practical measurement is performed before and after pressing, the relevant holes and surfaces as shown. The FE model is created to mimic the dressing when the ring wheel is in place after pressing.

    The analysis shows that the material does not plasticize due to the radial displacement caused by the ring wheel. The FE simulation, on the other hand, shows that deformations occur on the relevant holes and surfaces examined during the practical measurement. Comparison between the results shows that the FE model provides a good picture of the deformation field and changes in the geometry that would mean that tolerances according to drawing would be difficult to obtain. Deviations between the results may be due to the simplifications made to the FE model but also to the measurement accuracy varied.

    FEM is considered to be applicable to create a better picture of the assembly process at an early stage before practical measurement was carried out. In order to avoid the drawing tolerances not being obtained, it is proposed that the aluminum housing be machined after pressing the ring wheel.

  • 121.
    Boberg, Arvid
    University of Skövde, School of Engineering Science.
    HRC implementation in laboratory environment: Development of a HRC demonstrator2018Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Eurofins is one of the world's largest laboratories which, among other things, offer chemical and microbiological analyses in agriculture, food and environment. Several 100.000 tests of various foods are executed each year at Eurofins’ facility in Jönköping and the current processes include much repeated manual tasks which could cause ergonomic problems. The company therefore wants to investigate the possibilities of utilizing Human-Robot Collaboration (HRC) at their facility. Human-Robot Collaboration is a growing concept that has made a big impression in both robot development and Industry 4.0. A HRC approach allow humans and robots to share their workspaces and work side by side, without being separated by a protective fence which is common among traditional industrial robots. Human-Robot Collaboration is therefore believed to be able to optimize the workflows and relieve human workers from unergonomic tasks.

    The overall aim of the research project presented is to help the company to gain a better understanding about the existing HRC technologies. To achieve this goal, the state-of-the-art of HRC had to be investigated and the needs, possibilities and limitations of HRC applications had to be identified at Eurofins’ facility. Once these have been addressed, a demonstrator could be built which could be used for evaluating the applicability and suitability of HRC at Eurofins.

    The research project presented used the design science research process. The state-of-the-art of HRC was studied in a comprehensive literature review, reviewing sterile robots and mobile robotics as well. The presented literature review could identify possible research gaps in both HRC in laboratory environments and mobile solutions for HRC applications. These areas studied in the literature review formed together the basis of the prepared observations and interviews, used to generate the necessary data to develop the design science research artefact, the demonstrator.

    ABB's software for robotic simulation and offline programming, RobotStudio, were used in the development of the demonstrator, with the collaborative robot YuMi chosen for the HRC implementation. The demonstrator presented in the research project has been built, tested and refined in accordance to the design science research process. When the demonstrator could illustrate an applicable solution, it was evaluated for its performance and quality using a mixed methods approach.

    Limitations were identified in both the performance and quality of the demonstrator's illustrated HRC implementation, including adaptability and sterility constraints. The research project presented could conclude that a HRC application would be possible at a station which were of interest by the company, but would however not be recommended due to the identified constraints. Instead, the company were recommended to look for stations which are more standardized and have less hygienic requirements. By the end of the research project, additional knowledge was contributed to the company, including how HRC can affect today's working methods at Eurofins and in laboratory environments in general.

  • 122.
    Boberg, Arvid
    University of Skövde, School of Engineering Science.
    Virtual lead-through robot programming: Programming virtual robot by demonstration2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the development of an application which allows a user to program a robot in a virtual environment by the use of hand motions and gestures. The application is inspired by the use of robot lead-through programming which is an easy and hands-on approach for programming robots, but instead of performing it online which creates loss in productivity the strength from offline programming where the user operates in a virtual environment is used as well. Thus, this is a method which saves on the economy and prevents contamination of the environment. To convey hand gesture information into the application which will be implemented for RobotStudio, a Kinect sensor is used for entering the data into the virtual environment. Similar work has been performed before where, by using hand movements, a physical robot’s movement can be manipulated, but for virtual robots not so much. The results could simplify the process of programming robots and supports the work towards Human-Robot Collaboration as it allows people to interact and communicate with robots, a major focus of this work. The application was developed in the programming language C# and has two different functions that interact with each other, one for the Kinect and its tracking and the other for installing the application in RobotStudio and implementing the calculated data into the robot. The Kinect’s functionality is utilized through three simple hand gestures to jog and create targets for the robot: open, closed and “lasso”. A prototype of this application was completed which through motions allowed the user to teach a virtual robot desired tasks by moving it to different positions and saving them by doing hand gestures. The prototype could be applied to both one-armed robots as well as to a two-armed robot such as ABB’s YuMi. The robot's orientation while running was too complicated to be developed and implemented in time and became the application's main bottleneck, but remained as one of several other suggestions for further work in this project.

  • 123.
    Brolin, Anna
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Engineering Science.
    An investigation of cognitive aspects affecting human performance in manual assembly2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Modern manufacturing systems seem to be shifting from mass production to mass customisation, which means that systems must be able to manage changes in customer demands and requirements, new technology as well as environmental demands. This in turn leads to an increase in product variants that need to be assembled. To handle this issue, well designed and presented information is vital for assembly workers to perform effective and accurate assembly tasks. In this thesis the main focus has been to find factors that affect human performance in manual assembly. A literature review was made on the subject of manufacturing and usability as well as basic cognitive abilities used to utilise information, such as memory. This investigation identified applicable factors for assessing human cognitive performance within the research field of manufacturing. The thesis further investigates how some of these factors are handled in manual assembly, using case studies as well as observational studies. The results show that how material and information are presented to the assembler needs to be considered in order to have a positive effect on the assembly operation. In addition, a full factorial experimental study was conducted to investigate different ways of presenting material and information at the workstation while using mixed assembly mode with product variants. The material presentation factor involved the use of a material rack compared to using an unstructured kit as well as a structured kit and the information presentation factor involved using a text and number instruction compared to a photograph instruction. The results showed that using a kit is favourable compared to the traditional material rack, especially when using a structured kit combined with photographic instruction. Furthermore, the use of unstructured kits can lead to better productivity and reduced perceived workload, compared to a material rack. Although they are perhaps not as good as using a structured kit, they most likely bring a lower cost, such as man-hour consumption and space requirements. However, the number of components in an unstructured kit needs to be considered in order to keep it on a manageable level. As a conclusion, several scenarios were developed in order to understand how different assembly settings can be used in order to improve human performance at the assembly workstation.

  • 124.
    Brolin, Anna
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Brolin, Erik
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Second cycle education program in virtual ergonomics and design2018In: Proceedings of the 20th Congress of the International Ergonomics Association (IEA 2018): Volume VII: Ergonomics in Design / [ed] Sebastiano Bagnara, Riccardo Tartaglia, Sara Albolino, Thomas Alexander, Yushi Fujita, Cham: Springer, 2018, Vol. 824, p. 1058-1065Conference paper (Refereed)
    Abstract [en]

    Current product and production development tends to become more complex where principal design decisions are made in very early development phases when product data only exist in virtual formats. To support this virtual product realisation process there exist a number of tools and technologies. Considering ergonomics and human factors in an increasingly complex process with often complex tools requires competent people able to handle multidisciplinary development challenges in a proactive manner. To answer the need for educational programs to cover these issues the School of Engineering Science at University of Skövde has developed a new master (second cycle) program Virtual Ergonomics and Design. The aim with the program is to give students and future product and production developers, necessary knowledge and skills to effectively use virtual tools for analysis, development, and verification of ergonomics and integrate ergonomics and user aspects into the product realisation process. This is achieved through a number of courses that partly forms a core within the subject Virtual product realisation but also provides in-depth knowledge in ergonomics. Students will in a possible future role as design or production engineers have a great influence on ergonomics in manufacturing departments but also better perception of ergonomics, higher motivation and knowledge of support tools and methods for ergonomics integration.

  • 125.
    Brolin, Anna
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, UK.
    Case, Keith
    Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, UK.
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Cognitive Aspects Affecting Human Performance in Manual Assembly2016In: Advances in Manufacturing Technology XXX / [ed] Yee Mey Goh, Keith Case, IOS Press, 2016, p. 231-236Conference paper (Refereed)
    Abstract [en]

    This paper concerns the handling of information in assembly work environments. Several studies involving both literature reviews, case studies andobservations were conducted to find factors that affect human performance in manual assembly. The main experiment with 36 subjects used a mixed method design with a quantitative study, including time and errors as dependant measures,a qualitative study, including workload ratings, and a questionnaire. The experiment involved the assembly of a pedal car and the components werepresented using structured kits, unstructured kits and material racks. Assembly information was presented as text & component numbers or photographs, and situations with and without component variation were considered. Among theresults it was found that assembly times and workload ratings were lower when using a kit, whereas using a material rack resulted in perceived decreased workflow and increased stress and frustration. Assembly times and workload ratings were lower when using photographs, whereas using text and numbers increased mental workload.

  • 126.
    Brolin, Anna
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Case, Keith
    Loughborough University, United Kingdom.
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Interaction Effects Affecting Human Performance in Manual Assembly2018In: Advances in Manufacturing Technology XXXII: Proceedings of the 16th International Conference on Manufacturing Research, incorporating the 33rd National Conference on Manufacturing Research, September 11–13, 2018, University of Skövde, Sweden / [ed] Peter Thorvald, Keith Case, Amsterdam, Netherlands: IOS Press, 2018, p. 265-270Conference paper (Refereed)
    Abstract [en]

    This paper presents an experimental study aimed at investigating interaction effects affecting personnel in manual assembly. The main experiment with 36 subjects used a mixed method design which included a quantitative study, including time and errors as dependent measures, and a qualitative study, including workload ratings and a questionnaire. The overall task in the experiment was to assemble components on a pedal car. The main factors involved were assembly information (text & component numbers or photographs), material presentation (using structured kits, unstructured kits and material racks) and component variation (situations with and without component variation). It was found that performance, measured in assembly time, was best when combining photographs with no component variants and when using an unstructured kit.

  • 127.
    Brolin, Anna
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, United Kingdom.
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Case, Keith
    Department of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, United Kingdom.
    Experimental study of cognitive aspects affecting human performance in manual assembly2017In: Production & Manufacturing Research, ISSN 2169-3277, Vol. 5, no 1, p. 141-163Article in journal (Refereed)
    Abstract [en]

    This study investigate different ways of presenting material and information at workstations while using mixed assembly mode with product variants. The experimental set up annotated an assembly line involving 36 subjects. The material presentation factor involved the use of a material rack compared to using an unstructured kit as well as a structured kit. The information presentation factor involved using a text and number instruction compared to a photograph instruction, and situations with and without component variation were considered. Results show that assembly times and workload ratings were lower when using a kit, whereas using a material rack resulted in perceived decreased workflow and increased stress and frustration. Moreover, assembly times and workload ratings were lower when using photographs, whereas using text and numbers increased mental workload. The results could be useful when planning work places and production systems in order to obtain a better workflow and an increased human performance. 

  • 128.
    Brolin, Erik
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Chalmers University of Technology.
    Anthropometric diversity and consideration of human capabilities: Methods for virtual product and production development2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Contemporary product and production development is typically carried out with the support of computer tools where the design of products and workstations are originated and evaluated within virtual environments. Ergonomics addresses factors important to consider in the product and production development process to ensure a good fit between humans and the items being designed. Digital human modelling (DHM) tools enable simulations and analyses of ergonomics in virtual environments. Anthropometry is central when using DHM tools for product and production development to ensure that the design fits the intended proportion of the targeted population from a physical perspective. Several methods have been prescribed to consider the anthropometric diversity that exists within human populations. Still many DHM based simulations in product and production development processes are done with approaches that are poor in representing anthropometric diversity. Hence, there is a need for better tools and methods that would support DHM tool users to more effectively and efficiently consider anthropometric diversity in the design process.

    In this thesis current methods for anthropometric diversity considerations have been reviewed and new methods and functionality have been developed and implemented in a DHM tool. Mathematical models have been developed to consider three specific parts important to the consideration of anthropometric diversity: generation of suitable test cases, prediction of missing anthropometric data and implementation of more diverse anthropometric variables such as strength and flexibility. Results show that the proposed methods are accurate and advantageous compared to approaches often used in industry today. The mathematical models for generation of suitable test cases and prediction of missing anthropometric data have been implemented in an anthropometric software module. The module has undergone usability testing with industry DHM tools users. The developed anthropometric module is shown to answer to relevant needs of DHM tool users and fit into the work processes related to DHM simulations and ergonomics analyses utilised in industry today.

  • 129.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Digital human arm models with variation in size, strength and range of motion2014In: / [ed] Masaaki Mochimaru and Makiko Kouchi, 2014Conference paper (Refereed)
    Abstract [en]

    Digital human modelling (DHM) systems can be used to simulate production processes and analyse the human-machine interaction, particularly at early design stages. The human-machine interaction is affected and limited by factors or characteristics belonging to the human user and the machine or product but also the surrounding environment. DHM systems consider in most cases only physical user capabilities and with focus on consideration of body size related anthropometric diversity. However, the human-machine interaction is not only affected by the size and proportions of a user but for example also the user´s muscle strength and range of motion (ROM). This paper describes a study where diversity in strength and ROM, together with diversity in body size, is implemented in the process of creating data for a group of human arm models. A literature study was done to investigate the diversity of strength and ROM and the correlation between such measurements and body size data. The results from the literature study showed that there is little correlation between body size, strength and ROM. The study also showed that there are few published studies where body size, strength and ROM have been tested at the same time. From the literature study, generic correlation coefficients between body size, strength and ROM were synthesized. Using these correlation coefficients and Principal Component Analysis, data for a group of 14 female arm models with varying body size, strength and ROM were calculated. The results show that it is possible to introduce additional variables such as strength and ROM, but also that data of the correlation between body size and other types of anthropometric measurements are scarce. New measurement studies are important to decrease the uncertainties when predicting correlation coefficients between body size, strength and ROM variables.

  • 130.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Design of a Digital Human Modelling Module for Consideration of Anthropometric Diversity2014In: Advances in Applied Digital Human Modeling / [ed] Vincent Duffy, AHFE Conference , 2014, p. 114-120Conference paper (Refereed)
  • 131.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Björkenstam, Staffan
    Fraunhofer-Chalmers Centre, Gothenburg, Sweden.
    Virtual test persons based on diverse anthropometric data for ergonomics simulations and analysis2017In: Proceedings of the 49th NES 2017 Conference "Joy at Work", Lund, August 20-23, 2017 / [ed] Anna-Lisa Osvalder, Mikael Blomé and Hajnalka Bodnar, Lund: Lund University, Faculty of Engineering , 2017, p. 232-239Conference paper (Refereed)
    Abstract [en]

    This paper describes a study where diverse anthropometric data is included in the process of generating data for a group of virtual test persons. Data on body size, strength and ROM were either collected on an individual level or predicted and synthesized and then used in cluster analyses to generate six unique virtual test persons. Results show that the method is able to generate detailed virtual test persons which enables more realistic and accurate simulations, as strength and ROM data is included into the motion prediction algorithms used to generate motions.

  • 132.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Industrial Development, Scania, Scania CV, Södertälje, Sweden / Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Örtengren, Roland
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Adaptive regression model for prediction of anthropometric data2017In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5549, Vol. 5, no 4, p. 285-305Article in journal (Refereed)
    Abstract [en]

    This paper presents and evaluates an adaptive linear regression model for the prediction of unknown anthropometric data based on a flexible set of known predictive data. The method is based on conditional regression and includes use of principal component analysis to reduce effects of multicollinearity between the predictive variables. Results from the study show that the proposed adaptive regression model produces more accurate predictions compared to a flat regression model based on stature and weight, and also compared to a hierarchical regression model, that uses geometric and statistical relationships between body measurements to create specific linear regression equations in a hierarchical structure. An additional evaluation shows that the accuracy of the adaptive regression model increases logarithmically with the sample size. Apart from the sample size, the accuracy of the regression model is affected by the number of, and on which measurements that are, variables in the predictive dataset.

  • 133.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Chalmers University of Technology, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Örtengren, Roland
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Adaptive regression model for synthesizing anthropometric population data2017In: International Journal of Industrial Ergonomics, ISSN 0169-8141, E-ISSN 1872-8219, Vol. 59, p. 46-53Article in journal (Refereed)
    Abstract [en]

    This paper presents the development of an adaptive linear regression model for synthesizing of missing anthropometric population data based on a flexible set of known predictive data. The method is based on a conditional regression model and includes use of principal component analysis, to reduce effects of multicollinearity between selected predictive measurements, and incorporation of a stochastic component, using the partial correlation coefficients between predicted measurements. In addition, skewness of the distributions of the dependent variables is considered when incorporating the stochastic components. Results from the study show that the proposed regression models for synthesizing population data give valid results with small errors of the compared percentile values. However, higher accuracy was not achieved when the number of measurements used as independent variables was increased compared to using only stature and weight as independent variables. This indicates problems with multicollinearity that principal component regression were not able to overcome. Descriptive statistics such as mean and standard deviation values together with correlation coefficients is sufficient to perform the conditional regression procedure. However, to incorporate a stochastic component when using principal component regression requires raw data on an individual level.

    Relevance to industry

    When developing products, workplaces or systems, it is of great importance to consider the anthropometric diversity of the intended users. The proposed regression model offers a procedure that gives valid results, maintains the correlation between the measurements that are predicted and is adaptable regarding which, and number of, predictive measurements that are selected.

  • 134.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Industrial Development, Scania CV, Södertälje.
    Örtengren, Roland
    Chalmers University of Technology, Gothenburg.
    Development and evaluation of an anthropometric module for digital human modelling systems2019In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5549, Vol. 7, no 1, p. 47-70Article in journal (Refereed)
    Abstract [en]

    This paper presents the development of a software module and a graphical user interface which aims to support the definition of anthropometry of manikins in a digital human modelling (DHM) tool. The module is developed from user interviews and literature studies, as well as mathematical methods for anthropometric diversity consideration. The module has functionality to create both single manikins and manikin families, where it is possible to combine or analyse different population datasets simultaneously. The developed module and its interface have been evaluated via focus group interviews and usability tests by DHM tool users. Results from the studies show that the developed module and its interface has relevant functionality, fits well into industrial work processes, and is easy to use. The study also identifies possibilities to further increase usability.

  • 135.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Industrial Development, Scania, Scania CV, Södertälje, Sweden / Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Örtengren, Roland
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Generation and evaluation of distributed cases by clustering of diverse anthropometric data2016In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5557, Vol. 5, no 3, p. 210-229Article in journal (Refereed)
    Abstract [en]

    This paper describes a study where diversity in body size, strength and joint range of motion, together with diversity in other capability measurements, is included in the process of generating data for a group of test cases using cluster analysis. Descriptive statistics and correlation data was acquired for 15 variables for different age groups and both sexes. Based on this data, a population of 10,000 individuals was synthesised using correlated random numbers. The synthesised data was used in cluster analyses where three different clustering algorithms were applied and evaluated; hierarchical clustering, k-means clustering and Gaussian mixture distribution clustering. Results from the study show that the three clustering algorithms produce groups of test cases with different characteristics, where the hierarchical and k-means algorithm give the most diverse results and where the Gaussian mixture distribution gives results that are in between the first two.

  • 136.
    Brolin, Erik
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Mahdavian, Nafise
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Industrial Development, Scania CV, Södertälje.
    Johansson, Joakim
    Bombardier Transportation Sweden AB, Västerås.
    Possibilities and challenges for proactive manufacturing ergonomics2019In: Proceedings of the 20th Congress of the International Ergonomics Association (IEA 2018): Volume VIII: Ergonomics and Human Factors in Manufacturing, Agriculture, Building and Construction, Sustainable Development and Mining / [ed] Sebastiano Bagnara, Riccardo Tartaglia, Sara Albolino, Thomas Alexander, Yushi Fujita, Cham: Springer, 2019, Vol. 825, p. 11-20Conference paper (Refereed)
    Abstract [en]

    This paper identifies and describes product development activities where ergonomics issues could be considered and illustrates how that could be done through a number of different approaches. The study is divided into two parts where an interview study is done to identify where in a product development process consideration of ergonomics issues are or could be done. The second part of the study includes an observation, motion capture and simulation study of current manufacturing operations to evaluate and compare three different assessment approaches; observational based ergonomics evaluation, usages of motion capture data and DHM simulation and evaluation. The results shows the importance of consideration of ergonomics in early development phases and that the ergonomics assessment process is integrated in the overall product and production development process.

  • 137.
    Brown González, Lorena
    et al.
    University of Skövde, School of Engineering Science.
    Palacios Certucha, Rodrigo
    University of Skövde, School of Engineering Science.
    The design of a playground toy2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The report describes the design of a safe (within EU regulations), ergonomic, attractive, sustainable, versatile and interactive playground toy for children from ages 7 to 11. The product aims to help children develop in different aspects: physical, emotional, social and mental, in a sustainable environment. This was developed from the identification and exploration of the factors that influence the design of playground toys. The design process was divided in the following main stages: an initial research of information, the interpretation of this data, the development of a concept, a test stage and the results. During the research, teachers and parents were interviewed and children were observed. Relevant information was also gathered. For the development, a set of creative techniques were applied and finally tested. Modifications based on the test were made to reach an accurate design. The work done was successful to the extent established initially; although, it can be subject to improvement. The main limit was that no tests were performed on a physical prototype, therefore, there is information not yet gathered and tests that would prove if some of the assumptions were true or false.  

  • 138.
    Brownlee, Alexander E. I.
    et al.
    University of Stirling, United Kingdom.
    Swan, Jerry
    University of York, United Kingdom.
    Senington, Richard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Kocsis, Zoltan A.
    The University of Manchester, United Kingdom.
    Conflict-free routing of multi-stop warehouse trucks2019In: Optimization Letters, ISSN 1862-4472, E-ISSN 1862-4480Article in journal (Refereed)
    Abstract [en]

    The recent interest in greater vehicular autonomy for factory and warehouse automation has stimulated research in conflict-free routing: a challenging network routing problem in which vehicles may not pass each other. Motivated by a real-world case study, we consider one such application: truck movements in a tightly constrained warehouse. We propose an extension of an existing conflict-free routing algorithm to consider multiple stopping points per route. A high level metaheuristic is applied to determine the route construction and assignment of vehicles to routes. 

  • 139.
    Bäck, Gustaf
    et al.
    University of Skövde, School of Engineering Science.
    Wall, Gustaf
    University of Skövde, School of Engineering Science.
    Effektiv Materialhantering: Konstruktion och hållfasthetsberäkning av materialhanteringslösning2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The company Furhoffs Rostfria AB located in Skövde has developed a new assembly method for kitchen-sinks. The method means a more effective assembly of kitchen-sinks but the transportation of the material to be assembled is still a moment requiring a lot of time. The goal of this work is to develop a material handling concept that facilitates this transport. To confirm the achievement of the set goal, a number of more specific goals are also set. These goals should be achieved for the most optimal solution regarding the number of work moments, time regarding usage, general requirements from the Swedish Work Environment Authority and requirements regarding sustainable development.

    To understand the functions that the concept should fulfill and to understand the ingoing parameters, a literature study is performed. The study is based on a number of sources including current scientific articles which represents the foundation regarding the method for sustainable development. Web sources, books with technical character and knowledge from Furhoffs Rostfria AB are used as a foundation for the remaining methods performed. The final concept satisfies four functions, to transport, to lift, to hold and to assort ingoing material.

    Different basic concepts are produced by using three different methods of generation of concepts, where different competences are included. A weighted concept selection matrix is used to select which concept that should be analyzed further. The chosen concept is analyzed regarding; the risk of tipping, items placed on the concept sliding around and the strength and the mechanics of the concept.

    The material strength analysis, performed by using the finite element method, evaluates acting moments, acting effective stresses and deformation of the concept. The concept is evaluated by creating a beam element analysis and by creating a shell element analysis. The conclusion from these analyzes is that, regarding the practical usage of the concept, an insignificant deformation is obtained. Regarding occurring effective stresses a safety factor of barely two is obtained compared to the yield limit of the chosen material.

    The concept fulfills all the goals and demands set and is evaluated as a functioning solution for the stated problem. Suggestions regarding further future improvements for the chosen concept are provided.

  • 140.
    Camacho Moreno, Dionisio
    et al.
    University of Skövde, School of Engineering Science.
    Giner Pérez, Jorge
    University of Skövde, School of Engineering Science.
    Mechanical Design of a Compliant Horseshoe2014Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The principal aim of this research is the design of a more compliant horseshoe which allows the natural expansion and compression of the horse hoof. Three different simulations have been carried out in by using Finite Element Method in order to know the behaviour of the horse hoof when is analysed under the same load conditions. First the hoof will be studied without any horseshoe to obtain the produced displacement by the hoof expansion. Once the displacement of the barefoot hoof is known, an assembly, in which a sample stiff horseshoe is attached to the hoof by nails, will be performed to obtain both the hoof displacement as the horseshoe one. Finally, after three different researches about the current horseshoes, different possible alternative materials and most commons attachment methods, a more flexible horseshoe will be created and analysed. The results obtained in the three simulations will be compared and commented. 

  • 141.
    Campillo, Jose
    et al.
    University of Skövde, School of Engineering Science.
    Garcia, Celia
    University of Skövde, School of Engineering Science.
    Creating a pleasurable aluminium packaging2015Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project has been carried out in collaboration with CC Pack, a Swedish packaging company located in Tibro, and under the supervision of University of Skövde.

    The aim of the project is the creation of a new aluminium packaging, with the intention of satisfying the highest number of customers' requirements, getting also a differentiation from the competitors.

    Archer’s model is followed during the design process. This model allows strengthening the efficiency of project design.

    The compilation of information in order to make a complete requirement classification is based on: CC Pack requirements, a study of customer needs focused on interviews and pilot study, and a literature study lead by Maslow’s hierarchy translated to design along with the 4 pleasures of Patrick Jordan.

    After the requirements classification, it is time to start with the concept generation phase. This phase consist of diverse methods of generation and evaluation of ideas, such as brainstorming or the weighted objective method, until a final solution is reached.

    This last solution, which consists of an aluminium tray surrounded by a cardboard structure, is communicated at the end of the project through illustrations created through design software such as PTC Creo Parametric and Photoshop.

    Conclusions obtained are quite positive in general, nevertheless there is still an aspect that could be improved. It is related to the shipping system and it is commented in chapter 7 conclusions.

    There is also a chapter devoted to propose possible future contributions in order to implement this project.

  • 142.
    Carlberger, Thomas
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Vilka hållfasthetsegenskaper har limfogen?: Simulering på Högskolan i Skövde ger svaren2014In: Fordonskomponenten, ISSN 2000-7299, no 3, p. 46-47Article, review/survey (Other (popular science, discussion, etc.))
    Abstract [sv]

    Att beräkna limfogars hållfasthet är inte helt enkelt, vilket beror på spänningskoncentrationens inflytande vid limfogens kanter.

    Materialmekanik vid Högskolan i Skövde har specialiserat sig på hållfasthetssimulering av limfogar genom kohesiv modellering.

  • 143.
    Carlsson, Annika
    University of Skövde, School of Engineering Science.
    Kapacitetsanalys av produktionsflöde: - Med hjälp av produktionssimulering och traditionella produktionstekniska verktyg2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Volvo GTO in Skövde belongs to manufacturing and supply engines for truck customers worldwide. All engines to be sent for export goes through a production flow, CBU-line. CBU-line is an assembly line that not since construction in 1996 has undergone any major layout changes of substance, although the details of the flow changed. The object of the project is that by analyzing access conditions in order to determine the flow capacity and to produce focus areas for future improvement efforts.

    The flow lacks a large amount of the production engineering data necessary to assess its capabilities. Based on this a number of methods have been used together to create a picture of the current state of flow. Methods such as time study, work-study and AviX study have been conducted to identify bottlenecks in flow. While it is clear how much work is categorized in value-added in whole flow and per station. In addition to these traditional production engineering tools, there have been a production simulation. Implemented analyzes consistently shows a common bottleneck in the production flow which becomes the focus of improvement efforts.

    Through simulation analysis, the flow technical capacity estimated to be approximately 40 % higher than the throughput that occurs in the flow today. Simulation Analysis based on one developed suggestion for improvement indicates a potential increase of 32 %. To create the conditions to achieve this requires systematic efforts to reduce the effect of interference and wastage in the flow comprising over 70 % of all activity in the flow. The work has proposed that with relatively simple means to reduce bottleneck and increase throughput through the flow.

  • 144.
    Carrera Artola, Iosu
    et al.
    University of Skövde, School of Engineering Science. Mondragon Unibertsitatea.
    Lucena Garcerán, Alejandro
    University of Skövde, School of Engineering Science. University of Málaga .
    Detection of Frazil Ice at Water Intakes at Träbena Power Station2014Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Frazil ice is a phenomenon that takes place in cold regions when the water of rivers, lakes or oceans is cooled under 0ºC. Several times during winter, frazil ice can appear at river Ätran, where Träbena hydropower plant is held by the company Wetterstad Consulting AB. Frazil ice particles contained in the flowing water are extremely sticky and adhere to any object placed in the water. Trash racks are used by the power plant at the water intakes to prevent any strange object to go into the turbines. However, frazil ice particles stick to the trash racks creating an ice blockage that interrupts the water inflow. In this situation, the power plant has to stop the production even for several months, due to the lack of water that reaches the turbines. In order to solve this problem, the company has installed a heating system on the trash racks that prevent the adhesion of frazil ice particles. This system is manually operated, and it is turned on or off based on the experience and predictions of the company. This heating system is very power consuming and every time it is turned on unnecessarily the company loses money. An automatic frazil ice detection system that turns on the heating system when needed is to be created. For that, several options have been analysed, and finally a capacitor-based sensor has been developed as a solution. The sensor consist of two steel plates coated with semi-transparent polycarbonate submerged underwater parallel placed in the space between the trash racks’ bars, forming this way a parallel plate capacitor. The capacitance of a capacitor depends exclusively on its geometry and the dielectric material between the plates. Hence when the water temperature is low enough, frazil ice particles stick to the plates of the capacitor and its capacitance will vary indicating that the accretion of frazil ice may block the water inflow. This variation is registered and a signal is send to the heating system to start operating. This way, the heating system is completely automated; no human intervention is needed at all.

  • 145.
    Cedenkvist, Kristin
    University of Skövde, School of Engineering Science.
    Utveckling av ett nytt ändbeslag för spinnakerbom2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    In this project a product development has been made of a spinnaker pole end fitting. The project has been made in cooperation with Seldén Mast AB; a company that is manufacturing sailing rigs and that is located in Gothenburg.

     

    The project has been following a design process that is inspired from Archer’s three-phase model, which consists of an analytical part, a creative part and an executive part. The project started with an extensive pre-study that contained a market analysis of existing fittings today and interviews with users. After the pre-study the concept generation started with a Brainstorming session and then continued with more structured methods as the Idea generator and Contrast thinking. The methods resulted in three different concepts that were presented for Seldén. These concepts were then made as CAD-models as well.

     

    The concept selection started with a questionnaire that was sent out to the user-group where the three different concepts were presented. Next selection method was The Weighted Objective Method. It was the same concept that was chosen in both methods and after some discussions with Seldén a final decision could be made.

     

    The project resulted in a fitting that has a softer, rounder shape and a more simple design than the fittings Seldén are using today. The new concept also had a more effective tripp trigger-solution and a design that will release the rope in a more simple way. On the back of the fitting a shock-absorber was placed in the shape of a rubber-plate.

  • 146.
    Chiet, Cheong Wen
    et al.
    Universiti Tunku Abdul Rahman, Malaysia.
    Ching, Ng Tan
    Universiti Tunku Abdul Rahman, Malaysia.
    Huat, Saw Lip
    Universiti Tunku Abdul Rahman, Malaysia.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Tzuu, Tan Jaw
    Universiti Tunku Abdul Rahman, Malaysia.
    The Integration of Lean and Green Manufacturing for Malaysian Manufacturers: A Literature Review to Explore the Synergies between Lean and Green Model2019In: International Conference on Sustainable Energy and Green Technology 2018 / [ed] Chong Wen Tong, Wang Chin-Tsan, Bernard Saw Lip Huat, Institute of Physics Publishing (IOPP), 2019, Vol. 268, article id 012066Conference paper (Refereed)
    Abstract [en]

    In general, profitability and efficiency have been the main interest for organization. However, the increasing concerns for the environment from government, regulators, customers and other stakeholders has forced companies to seek for alternatives to achieve green objectives. The difficulties faced by organizations are lack of awareness and guideline in implementing green practices in their daily operation. Under constrained resources, employers are reluctant to spend money on something unclear. During the last decade, lean manufacturing seems to be visible trend in most of the manufacturing industries in Malaysia. As lean tends to emphasize on waste reduction, it provides similarity between lean and green. Therefore, it is a better atmosphere to deploy green practices and tools under existing lean manufacturing. The purpose of this paper is to present a review on the synergies between green and lean and identifying the determinants that affecting both lean and green manufacturing for Malaysian manufacturers. The determinant obtained are financial benefit, incentive, legislation, stakeholder, management commitment, technology, environmental awareness and brand image or competitiveness. Besides, the authors identified and suggested future research directions on developing an integrated lean-green model for daily operation. This study aims to assist researchers to identify the opportunities and challenges on lean-green model and this review is useful for manufacturers and government in developing manufacturing policies and guideline.

  • 147.
    Christensen, Mick
    et al.
    University of Skövde, School of Engineering Science.
    Thörn, Albin
    University of Skövde, School of Engineering Science.
    Framtagning av automatiserat layoutförslag: Layout med human robot-kollaboration2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The industry today stands before challenges because of products shortened lifecycle and increased variation. Present systems are having a difficult time handling these demands. Collaborative robots (cobots) have been developed to overcome these problems and creating flexible and adjustable automation processes. Parker Hannifin in Skövde is a manufacturer of hydraulic and pneumatic couplings. All assembly is done manually at present, which can cause issues ergonomically for the workers. The productivity and quality are not suffering from any major problem now, still the company sees reasons to automate parts of the production. Partly because the importance of always trying to improve the production and ergonomic, but also the renewal of the company that follows is a reason.

    The purpose of the project is to find a workstation suitable for collaborative automation. The station and the processes are then to be studied to define what is needed for improvement through an automated layout. The goal is that the project will work as support for future decision concerning an investment. Different stations and moments will be studied for choosing an appropriate process to automate. Information regarding components needs to be collected, for mapping the needs of the layout. Comparisons will then be made from the concept’s parameters. Yearly cost between collaborative and manual station will be compared based on an approximately life time of the investment.

    Product type 1 is a new type of spill free product and its volume have good conditions to increase inthe future. Today the stations for manufacturing product type 1 and 2 have a high occupation. Station X was considered an appropriate candidate and was chosen for the project. After a compilation of the comparisons been made, the robot model UR5 from Universal Robots with a gripper from Robotiq and vision system from Sick, was chosen. A proposed layout was made where the robot is performing the last moments, 11‐15, of the assembly. The results showed that with an approximate life time of seven years, the investment would not be financially profitable compared to manual labour. The implementation should instead be investigated in a different station, concerning the high production volume that is needed in station X.

    The work has resulted in several solution for moments not included in the proposition. The project is still viewed as successful and the work as useful support for the future, despite results showing that the layout is not more profitable than today’s manual assembly. It is just not the economical aspect that is important to reflect over, but quality and ergonomic are fields that can benefit from collaborative robots.

  • 148.
    Clavero Bernal, Sergio
    et al.
    University of Skövde, School of Engineering Science.
    Fernandez Perrote, Clara
    University of Skövde, School of Engineering Science.
    Detailed flow simulation of AGV traffic and material handling2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of the project is to make comparisons and evaluate single lane with two-way traffic flow, different ways of ordering and signal handling in a specific area of VCBC Upper Plant in Olofström. For that purpose, the simulation has been built with the support of the discrete event simulation software Tecnomatix Plant Simulation by Siemens to analyze the different outcomes and scenarios, in order to get a better understanding of how it currently works and the future improvements that could be implemented in the model. The final aim is to get a more efficient material flow in the production line, as well as better AVG traffic in the mentioned area.

    The accomplishment of this project was carried out in collaboration with Volvo Cars Engine Skövde and VCBC Volvo Olöfstrom and the University of Skövde, Sweden in order to achieve the Bachelor degree in Automation Engineering and providing all the necessary material and data to build this model.

    The results show a clear improvement after implementing a second track in the model, with different impacts in different stations but with a noticeable gain in the overall efficiency in all of them.

  • 149.
    Cohen Laizerowitch, Alexis
    et al.
    University of Skövde, School of Engineering Science.
    Gómez Reyes, Alejandro
    University of Skövde, School of Engineering Science.
    Furniture design within an existing line of products focused on CAD modelling2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report aims to covers the conduction of a final thesis project for the University of Skövde in collaboration with J.Design studio (Stockholm).

    The purpose of this project is applying and evaluating CAD and different tools related to the field of 3D CAD within design and product development phases. This has been achieved by the development of two pieces of furniture from a defined line of products stated by existing clients of J.Design.

    The initial phase of the project was knowing the design limitations from both clients and their stakeholders. Once these limitations were known, a pre-study phase where 3D CAD modelling was set as the key tool for the research was done. This research identified related tools with CAD that are applied during the development design phase. Starting the development of the two case studies, the user needs’ phase was the first step in the process, followed by a benchmarking study, an ergonomics study, and finally, setting these requirements into a requirement list. Then, the design development phase took place, covering initial sketches until the detailed final solutions. As a final step, the use of the identified tools was evaluated and analysed based on the experience from the two case studies of this thesis project.

    From this evaluation came the conclusion that these tools need to take part in the design phase in a certain moment depending on the level of development, and as the level of sophistication of the tool increases, the information and detail provided are also higher.

  • 150.
    Conder, Marston
    et al.
    University of Auckland, New Zealand.
    Stokes, Klara
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. National University of Ireland Maynooth, Co. Kildare, Ireland.
    New methods for finding minimum genus embeddings of graphs on orientable and non-orientable surfaces2019In: Ars Mathematica Contemporanea, ISSN 1855-3966, Vol. 17, no 1, p. 1-35Article in journal (Refereed)
    Abstract [en]

    The question of how to find the smallest genus of all embeddings of a given finite connected graph on an orientable (or non-orientable) surface has a long and interesting history. In this paper we introduce four new approaches to help answer this question, in both the orientable and non-orientable cases. One approach involves taking orbits of subgroups of the automorphism group on cycles of particular lengths in the graph as candidates for subsets of the faces of an embedding. Another uses properties of an auxiliary graph defined in terms of compatibility of these cycles. We also present two methods that make use of integer linear programming, to help determine bounds for the minimum genus, and to find minimum genus embeddings. This work was motivated by the problem of finding the minimum genus of the Hoffman-Singleton graph, and succeeded not only in solving that problem but also in answering several other open questions.

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