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  • 151.
    De Vin, Leo J.
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos H. C.University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    2009Collection (editor) (Other academic)
  • 152.
    de Vin, Leo J
    et al.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H CUniversity of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.Thorvald, PeterUniversity of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.Sullivan, William GVirginia Tech, USA.Ahmad, MunirUniversity of Teesside, UK.
    Proceedings of the 18 th International Conference on Flexible Automation and Intelligent Manufacturing FAIM 2008: June 30th  – July 2nd, 2008 University of Skövde, Sweden2008Conference proceedings (editor) (Refereed)
  • 153.
    De Vin, Leo
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Solding, P.
    Swerea SWECAST AB.
    Ng, Amos
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Approaches to Energy Efficiency Assessment and Management: A State of the Art Study2009In: Proceedings of the 26th International Manufacturing Conference / [ed] Garret E O'Donnell; Kevin Kelly; Irish Manufacturing Committee., Department of Mechanical and Manufacturing Engineering, Trinity College Dublin , 2009, p. 9-16Conference paper (Refereed)
    Abstract [en]

    Electricity prices have gone up significantly during the last decade, and in some countries, the electricity price is very volatile. There exist a number of policies and regulations to control the electricity market and to stimulate energy efficiency, but these are often not very transparent. Furthermore, indicators for energy efficiency can be misleading or difficult to measure. Although there are a number of approaches to modelling and simulation of energy consumption and energy optimisation, these approaches have some drawbacks such as prohibitive computing times, difficulties to address dynamic situations, and the lack of a holistic view on the manufacturing system. Other problems include the limited availability of data at the appropriate level of aggregation; sometimes the level is too low, in other cases too high. However, recently promising attempts have been made to use Discrete Event Simulation for energy modelling and production planning. It is believed that this, in combination with other ICT tools such as multi-objective optimisation, offers a promising way forward beyond current state of the art.

  • 154.
    Deb, Kalyanmoy
    et al.
    Michigan State University.
    Bandaru, Sunith
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Engineering Science.
    Greiner, David
    Universidad de Las Palmas de Gran Canaria.
    Gaspar-Cunha, António
    University of Minho, Campus de Azurém.
    Tutum, Cem Celal
    Michigan State University.
    An integrated approach to automated innovization for discovering useful design principles: Case studies from engineering2014In: Applied Soft Computing, ISSN 1568-4946, E-ISSN 1872-9681, Vol. 15, no 2, p. 42-56Article in journal (Refereed)
    Abstract [en]

    Computational optimization methods are most often used to find a single or multiple optimal or near-optimal solutions to the underlying optimization problem describing the problem at hand. In this paper, we elevate the use of optimization to a higher level in arriving at useful problem knowledge associated with the optimal or near-optimal solutions to a problem. In the proposed innovization process, first a set of trade-off optimal or near-optimal solutions are found using an evolutionary algorithm. Thereafter, the trade-off solutions are analyzed to decipher useful relationships among problem entities automatically so as to provide a better understanding of the problem to a designer or a practitioner. We provide an integrated algorithm for the innovization process and demonstrate the usefulness of the procedure to three real-world engineering design problems. New and innovative design principles obtained in each case should clearly motivate engineers and practitioners for its further application to more complex problems and its further development as a more efficient data analysis procedure.

  • 155.
    Deb, Kalyanmoy
    et al.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre. Indian Institute of Technology, Kanpur, Uttar Pradesh, India / Aalto University School of Economics , Finland.
    Datta, Rituparna
    ndian Institute of Technology, Kanpur, Uttar Pradesh, India.
    A bi-objective constrained optimization algorithm using a hybrid evolutionary and penalty function approach2013In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 45, no 5, p. 503-527Article in journal (Refereed)
    Abstract [en]

    Constrained optimization is a computationally difficult task, particularly if the constraint functions are nonlinear and non-convex. As a generic classical approach, the penalty function approach is a popular methodology which degrades the objective function value by adding a penalty proportional to the constraint violation. However, the penalty function approach has been criticized for its sensitivity to the associated penalty parameters. Since its inception, evolutionary algorithms have been modified in various ways to solve constrained optimization problems. Of them, the recent use of a bi-objective evolutionary algorithm in which the minimization of the constraint violation is included as an additional objective has received significant attention. In this article, a combination of a bi-objective evolutionary approach with the classical penalty function methodology is proposed, in a manner complementary to each other. The evolutionary approach provides an appropriate estimate of the penalty parameter, while the solution of an unconstrained penalized function by a classical method induces a convergence property to the overall hybrid algorithm. The working of the procedure on a number of standard numerical test problems and an engineering design problem is demonstrated. In most cases, the proposed hybrid methodology is observed to take one or more orders of magnitude fewer function evaluations to find the constrained minimum solution accurately than some of the best reported existing methodologies.

  • 156.
    Deb, Kalyanmoy
    et al.
    Department of Electrical and Computer Engineering, Michigan State University, USA.
    Siegmund, Florian
    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.
    R-HV: A Metric for Computing Hyper-volume for Reference Point-based EMOs2015In: Swarm, Evolutionary, and Memetic Computing: 5th International Conference, SEMCCO 2014, Bhubaneswar, India, December 18-20, 2014, Revised Selected Papers / [ed] Bijaya Ketan Panigrahi, Ponnuthurai Nagaratnam Suganthan & Swagatam Das, Springer, 2015, p. 98-110Chapter in book (Refereed)
    Abstract [en]

    For evaluating performance of a multi-objective optimizationfor finding the entire efficient front, a number of metrics, such as hypervolume, inverse generational distance, etc. exists. However, for evaluatingan EMO algorithm for finding a subset of the efficient frontier, the existing metrics are inadequate. There does not exist many performancemetrics for evaluating a partial preferred efficient set. In this paper, wesuggest a metric which can be used for such purposes for both attainableand unattainable reference points. Results on a number of two-objectiveproblems reveal its working principle and its importance in assessingdifferent algorithms. The results are promising and encouraging for itsfurther use.

  • 157.
    Delfs, Niclas
    et al.
    Fraunhofer-Chalmers Research Centre, Gothenburg, Sweden.
    Bohlin, Robert
    Fraunhofer-Chalmers Research Centre, Gothenburg, Sweden.
    Hanson, Lars
    Industrial Development, Scania CV, Södertälje, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Carlson, Johan S.
    Fraunhofer-Chalmers Research Centre, Gothenburg, Sweden.
    Introducing Stability of Forces to the Automatic Creation of Digital Human Postures2013Conference paper (Refereed)
    Abstract [en]

    Although the degree of automation is increasing in manufacturing industries, many assembly operations are performed manually. To avoid injuries and to reach sustainable production of high quality, comfortable environments for the operators are vital. Poor station layouts, poor product designs or badly chosen assembly sequences are common sources leading to unfavorable poses and motions. To keep costs low, preventive actions should be taken early in a project, raising the need for feasibility and ergonomics studies in virtual environments long before physical prototypes are available. Today, in the automotive industries, such studies are conducted to some extent. The full potential, however, is far from reached due to limited software support in terms of capability for realistic pose prediction, motion generation and collision avoidance. As a consequence, ergonomics studies are time consuming and are mostly done for static poses, not for full assembly motions. Furthermore, these ergonomic studies, even though performed by a small group of highly specialized simulation engineers, show low reproducibility within the group.Effective simulation of manual assembly operations considering ergonomic load and clearance demands requires detailed modeling of human body kinematics and motions as well as a fast and robust inverse kinematics solver. In this paper we introduce a stability measure rewarding poses insensitive to variations in contact points and contact forces. Normally this has been neglected and only the balance of moment and forces has been taken into account. The manikin used in this work has 162 degrees of freedom and uses an exterior root. To describe operations and facilitate motion generation, the manikin is equipped with coordinate frames attached to end-effectors like hands and feet. The inverse kinematic problem is to find joint values such that the position and orientation of hands and feet matches certain target frames during an assembly motion. This inverse problem leads to an underdetermined system of equations since the number of joints exceeds the end-effectors’ constraints. Due to this redundancy there exist a set of solutions, allowing us to pick a solution that maximizes a scalar valued comfort function. Many objectives are included in the comfort function, for example in terms of joint angles, joint moments and solid objects’ distance to the manikin. The proposed stability measure complements the earlier balance criterion and is combined into the comfort function. By increasing the importance of this function the digital human model will reposition to a more stable pose. The digital human model will be tested on a set of challenging assembly operations taken from the automotive industry to show the effect of the stability measure.

  • 158.
    Dudas, Catarina
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Aslam, Tehseen
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Frequent Itemset Mining to Generate Initial Solutions for Simulation-Based Optimization of Warehouse Product Placement2010In: SCMIS 2010: Proceedings of the 8th International Conference on Supply Chain Management and Information Systems (Conference Theme: Logistics Systems and Engineering) 6th-8th October 2010 Hong Kong, China, Hong Kong: The Hong Kong Polytechnic University , 2010Conference paper (Refereed)
    Abstract [en]

    Warehouses are obliged to optimize their operations with regard to  multiple  objectives,  such  as  maximizing  effective  use  space, equipment,  labor,  maximize  accessibility  of  products,  maximize amount of processed orders and all this should be achieved whilst minimizing  order  processing  times,  distance  traveled,  broken promises, errors and not to forget the operational cost. A product placement problem for a warehouse is in focus of this study and the main goal is to decrease the picking time for each pick run in order to gain higher efficiency.  To achieve this, a simulation model is built as a representation of the warehouse. As the complexity and the size of the number  of input   variable   grow   it   is   essential   to   use   simulation-based optimization in order to receive a satisfying result. A set of initial solutions  for  the  simulation-based  optimization  is  needed;  since the  number  of  products  to  place  in  the  warehouse  is  huge  this solution ought to be intelligent. This paper describes a technique for  generating  such  a  set  of  solutions  through  searching  for frequent itemsets in the transaction  database. It is  believed that frequent products usually picked simultaneously should be stored closed together.

  • 159.
    Dudas, Catarina
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Boström, Henrik
    University of Skövde, The Informatics Research Centre. University of Skövde, School of Humanities and Informatics.
    Using Uncertain Chemical and Thermal Data to Predict Product Quality in a Casting Process2009In: Proceedings of the 1st ACM SIGKDD Workshop on Knowledge Discovery from Uncertain Data / [ed] Jian Pei; Lise Getoor; Ander De Keijzer, AMC, Inc. , 2009, p. 57-61Conference paper (Refereed)
    Abstract [en]

    Process and casting data from different sources have been collected and merged for the purpose of predicting, and determining what factors affect, the quality of cast products in a foundry. One problem is that the measurements cannot be directly aligned, since they are collected at different points in time, and instead they have to be approximated for specific time points, hence introducing uncertainty. An approach for addressing this problem is investigated, where uncertain numeric features values are represented by intervals and random forests are extended to handle such intervals. A preliminary experiment shows that the suggested way of forming the intervals, together with the extension of random forests, results in higher predictive performance compared to using single (expected) values for the uncertain features together with standard random forests.

  • 160.
    Dudas, Catarina
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Frantzén, Marcus
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos H.C.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    A synergy of multi-objective optimization and data mining for the analysis of a flexible flow shop2011In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 27, no 4, p. 687-695Article in journal (Refereed)
    Abstract [en]

    A method for analyzing production systems by applying multi-objective optimization and data mining techniques on discrete-event simulation models, the so-called Simulation-based Innovization (SBI) is presented in this paper. The aim of the SBI analysis is to reveal insight on the parameters that affect the performance measures as well as to gain deeper understanding of the problem, through post-optimality analysis of the solutions acquired from multi-objective optimization. This paper provides empirical results from an industrial case study, carried out on an automotive machining line, in order to explain the SBI procedure. The SBI method has been found to be particularly siutable in this case study as the three objectives under study, namely total tardiness, makespan and average work-in-process, are in conflict with each other. Depending on the system load of the line, different decision variables have been found to be influencing. How the SBI method is used to find important patterns in the explored solution set and how it can be valuable to support decision making in order to improve the scheduling under different system loadings in the machining line are addressed.

  • 161.
    Dudas, Catarina
    et al.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Hedenstierna, Philip
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Simulation-based innovization for manufacturing systems analysis using data mining and visual analytics2011In: Proceedings of the 4th Swedish Production Symposium, 2011, p. 374-382Conference paper (Refereed)
  • 162.
    Dudas, Catarina
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Boström, Henrik
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Information Extraction from Solution Set of Simulation-based Multi-objective Optimisation using Data Mining2009In: Proceedings of Industrial Simulation Conference 2009 / [ed] D. B. Das, V. Nassehi & L. Deka, EUROSIS-ETI , 2009, p. 65-69Conference paper (Refereed)
    Abstract [en]

    In this work, we investigate ways of extracting information from simulations, in particular from simulation-based multi-objective optimisation, in order to acquire information that can support human decision makers that aim for optimising manufacturing processes. Applying data mining for analyzing data generated using simulation is a fairly unexplored area. With the observation that the obtained solutions from a simulation-based multi-objective optimisation are all optimal (or close to the optimal Pareto front) so that they are bound to follow and exhibit certain relationships among variables vis-à-vis objectives, it is argued that using data mining to discover these relationships could be a promising procedure. The aim of this paper is to provide the empirical results from two simulation case studies to support such a hypothesis.

  • 163.
    Dudas, Catarina
    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. University of Skövde.
    Boström, Henrik
    Department of Computer and Systems Sciences, Stockholm University, Kista, Sweden.
    Post-analysis of multi-objective optimization solutions using decision trees2015In: Intelligent Data Analysis, ISSN 1088-467X, E-ISSN 1571-4128, Vol. 19, no 2, p. 259-278Article in journal (Refereed)
    Abstract [en]

    Evolutionary algorithms are often applied to solve multi-objective optimization problems. Such algorithms effectively generate solutions of wide spread, and have good convergence properties. However, they do not provide any characteristics of the found optimal solutions, something which may be very valuable to decision makers. By performing a post-analysis of the solution set from multi-objective optimization, relationships between the input space and the objective space can be identified. In this study, decision trees are used for this purpose. It is demonstrated that they may effectively capture important characteristics of the solution sets produced by multi-objective optimization methods. It is furthermore shown that the discovered relationships may be used for improving the search for additional solutions. Two multi-objective problems are considered in this paper; a well-studied benchmark function problem with on a beforehand known optimal Pareto front, which is used for verification purposes, and a multi-objective optimization problem of a real-world production system. The results show that useful relationships may be identified by employing decision tree analysis of the solution sets from multi-objective optimizations.

  • 164.
    Dudas, Catarina
    et al.
    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.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Boström, Henrik
    Department of Computer and Systems Sciences, Stockholm University, Stockholm, Sweden.
    Integration of data mining and multi-objective optimisation for decision support in production system development2014In: International journal of computer integrated manufacturing (Print), ISSN 0951-192X, E-ISSN 1362-3052, Vol. 27, no 9, p. 824-839Article in journal (Refereed)
    Abstract [en]

    Multi-objective optimisation (MOO) is a powerful approach for generating a set of optimal trade-off (Pareto) design alternatives that the decision-maker can evaluate and then choose the most-suitable configuration, based on some high-level strategic information. Nevertheless, in practice, choosing among a large number of solutions on the Pareto front is often a daunting task, if proper analysis and visualisation techniques are not applied. Recent research advancements have shown the advantages of using data mining techniques to automate the post-optimality analysis of Pareto-optimal solutions for engineering design problems. Nonetheless, it is argued that the existing approaches are inadequate for generating high-quality results, when the set of the Pareto solutions is relatively small and the solutions close to the Pareto front have almost the same attributes as the Pareto-optimal solutions, of which both are commonly found in many real-world system problems. The aim of this paper is therefore to propose a distance-based data mining approach for the solution sets generated from simulation-based optimisation, in order to address these issues. Such an integrated data mining and MOO procedure is illustrated with the results of an industrial cost optimisation case study. Particular emphasis is paid to showing how the proposed procedure can be used to assist decision-makers in analysing and visualising the attributes of the design alternatives in different regions of the objective space, so that informed decisions can be made in production systems development.

  • 165.
    Eklind, Alexander
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Walander, Tomas
    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.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    High cycle fatigue crack growth in Mode I of adhesive layers: modelling, simulation and experiments2014In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 190, no 1-2, p. 125-146Article in journal (Refereed)
    Abstract [en]

    The capability to predict high cycle fatigue properties of adhesive joints is important for cost-efficient and rapid product development in the modern automotive industry. Here, the adaptability of adhesives facilitates green technology through the widening of options of choosing and joining optimal materials. In the present paper a continuum damage mechanics model is developed based on the adhesive layer theory. In this theory, through-thickness averaged variables for the adhesive layer are used to characterise the deformation, damage and local loading on the adhesive layer. In FE-simulations, cohesive elements can thereby be used to model the adhesive layer. This simplifies simulations of large scale complex built-up structures. The model is adapted to experimental results for two very different adhesive systems; one relatively stiff rubber based adhesive and one soft polyurethane based adhesive. The model is able to reproduce the experimental results with good accuracy except for the early stage of crack propagation when the loads are relatively large. The model also predicts a threshold value for fatigue crack growth below which no crack growth occurs. The properties of the model are also compared with the properties of Paris’ law. The relations between the parameters of the continuum damage mechanics law and the parameters of Paris’ law are used to adapt the new law. It also shows that the properties of a joined structure influence the Paris’ law properties of the adhesive layer. Thus, the Paris’ law properties of an adhesive layer are not expected to be transferable to joints with adherends having different mechanical properties.

  • 166.
    Endrias, Dawit H.
    et al.
    TS Tech Canada Inc..
    Feng, Hsi-Yung
    The University of British Columbia.
    Ma, Ji
    The University of British Columbia.
    Wang, Lihui
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Taher, M. Abu
    The University of Western Ontario.
    A combinatorial optimization approach for evaluating minimum-zone spatial straightness errors2012In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 45, no 5, p. 1170-1179Article in journal (Refereed)
    Abstract [en]

    This paper presents a new and robust approach for the accurate evaluation of minimumzone spatial straightness error from a set of coordinate measurement data points. The algorithm iteratively searches for the specific data points that define the minimum bound of the spatial straightness zone using combinatorial optimization. It is based on the fact that the minimum circumscribed cylinder of a point set, which is equivalent to the minimum spatial straightness zone of the measurement data, will pass through three, four, or five of the data points that constitute the convex hull vertices of the entire data set. Computed results have shown that although the presented approach may lead to increased computational time, it is robust and able to construct the exact minimum circumscribed cylinder for a given point set. The minimum-zone spatial straightness error can thus be evaluated with the best possible accuracy. The advantage of the presented algorithm is demonstrated via comparison with published computed results of existing algorithms.

  • 167.
    Ericson, Stefan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Vision-Based Perception for Localization of Autonomous Agricultural Robots2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis Stefan investigates how cameras can be used for localization of an agricultural mobile robot. He focuses on relative measurement that can be used to determine where a weeding tool is operating relative a weed detection sensor. It incorporates downward-facing perspective cameras, forward-facing perspective cameras and omnidirectional cameras. Stefan shows how the camera’s ego-motion can be estimated to obtain not only the position in 3D but also the orientation. He also shows how line structures in the field can be used to navigate a robot along the rows.

  • 168.
    Ericson, Stefan K.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Åstrand, Björn S.
    School of Information Science, Computer and Electrical Engineering, Halmstad University, Halmstad, Sweden.
    Analysis of two visual odometry systems for use in an agricultural field environment2018In: Biosystems Engineering, ISSN 1537-5110, E-ISSN 1537-5129, Vol. 166, p. 116-125Article in journal (Refereed)
    Abstract [en]

    This paper analyses two visual odometry systems for use in an agricultural field environment. The impact of various design parameters and camera setups are evaluated in a simulation environment. Four real field experiments were conducted using a mobile robot operating in an agricultural field. The robot was controlled to travel in a regular back-and-forth pattern with headland turns. The experimental runs were 1.8–3.1 km long and consisted of 32–63,000 frames. The results indicate that a camera angle of 75° gives the best results with the least error. An increased camera resolution only improves the result slightly. The algorithm must be able to reduce error accumulation by adapting the frame rate to minimise error. The results also illustrate the difficulties of estimating roll and pitch using a downward-facing camera. The best results for full 6-DOF position estimation were obtained on a 1.8-km run using 6680 frames captured from the forward-facing cameras. The translation error (x,y,z) is 3.76% and the rotational error (i.e., roll, pitch, and yaw) is 0.0482 deg m−1. The main contributions of this paper are an analysis of design option impacts on visual odometry results and a comparison of two state-of-the-art visual odometry algorithms, applied to agricultural field data.

    The full text will be freely available from 2020-03-01 00:01
  • 169.
    Eriksson, David
    et al.
    University of Borås, Sweden.
    Hilletofth, Per
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    The importance of the retailer for an OEM developing innovative products2011In: Conradi Research Review, ISSN 1459-0980, Vol. 6, no 2, p. 63-81Article in journal (Refereed)
    Abstract [en]

    The supply chain strategy research has generated many frameworks for matching the supply chain with the nature of demand, market, consumers, or products. Recently many companies have implemented innovative new product development processes in order to increase revenue. However, research on the importance of the retailers for an original equipment manufacturer (OEM) adopting a leagile supply chain strategy for innovative products, is scarce. Using the case study method, this research investigates the need of collaboration between an OEM and its retailers. This research aims to richen the knowledge about demand supply chain management (DSCM), and the coordination of demand and supply processes between companies in the demand-supply chain. This research shows that there are several measures that may be used to monitor performance, and that collaboration is important for the case company.

  • 170.
    Eriksson, David
    et al.
    University of Borås.
    Hilletofth, Per
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    The Role of Consumer Insight in New Product Development and Its Impact on Supply Chain Management: A Swedish Case Study2010In: Innovative Process Optimization Methods in Logistics: Emerging trends, concepts and technologies / [ed] Thorsten Blecker, Wolfgang Kersten, Christian Lüthje, Berlin: Erich Schmidt Verlag, 2010, p. 113-126Conference paper (Refereed)
    Abstract [en]

    This paper seeks to explore how a profound consumer understanding may influence the early stages of a new product development (NPD) process. The issue is examined through a qualitative single case study combined with a literature review. The case study shows how the NPD process is structured and executed in a Swedish furniture company as well as the role consumer insight plays in that process. Empirical data have been collected mainly from in-depth interviews with persons representing senior and middle management in the case company. The research reveals that consumer oriented, cross-functional NPD in the case company has a strong impact on internal collaboration, and aligns the goals between different departments and functions within the company. Despite inefficiencies on departmental level, effectiveness on company level is achieved. Early indications show an expected growth in contribution margins by 8 percentage.

  • 171.
    Eriksson, Nomie
    University of Skövde, School of Business. University of Skövde, The Virtual Systems Research Centre.
    Maintaining Healthcare Organizations’ Reliability in Times of Change2014In: British Academy of Management 2014: Track: Organizational Transformation, Change and Development / [ed] Catherine McCauley-Smith, London, 2014, p. 1-18Conference paper (Refereed)
    Abstract [en]

    Healthcare organizations should be reliable and resilient when unexpected events occur that create pressure for change. This paper discusses the importance of reliability and resilience when a decision is made to standardize the professionals’ work methods.

    The aim was to explain how healthcare organizations can maintain high reliability in the operations beyond an unexpected event.

    Two qualitative case studies at two hospitals are used to compare the work methods. Semi-structured interviews and follow-up questions were conducted with managers, nurses, and physicians in departments of cardiology and urology. Annual reports and operation plans also provide data.   

    High reliability healthcare organization is sufficiently resilient in times of change if providing quality care, encourages flexibility, individual responsibility, promotes good communication, develops learning processes and gives legitimacy.  

    Professionals need participate in decision-making processes and require time and opportunity to develop knowledge and skills.

  • 172.
    Evansluong, Quang
    et al.
    Lund University School of Economics and Management.
    Boers, Börje
    University of Skövde, School of Business. University of Skövde, Enterprises for the Future.
    Ljungkvist, Torbjörn
    University of Skövde, School of Business. University of Skövde, Enterprises for the Future.
    Ujvari, Sandor
    University of Skövde, School of Business. University of Skövde, Enterprises for the Future. University of Skövde, The Virtual Systems Research Centre.
    The family influences of EO development in immigrant family businesses2018In: Sustainable entrepreneurship: A win-win strategy for the future, Toledo, 2018Conference paper (Refereed)
    Abstract [en]

    This paper explores how family influences the entrepreneurial orientation (EO) process in immigrant family business. To fulfill the purpose, we employ inductive multiple case studies with in-depth interviews.  We rely on seven cases of immigrant entrepreneurs of Chinese, Icelandic, Turkish, Cameroonian, Mexican and Lebanese who established firms in Sweden. Our results suggest that EO development trajectories vary in regard to first and second immigrant entrepreneurs, low and high-tech sectors and host and home countries. Thus, family dynamics facilitates the development of entrepreneurial orientation over time through transforming, translating and transferring across generations and contexts. Our study indicates that, through family dynamics, EO is developed as a (1) transferring process of the founders’ proactiveness between the family in the home and host country; (2) translating process of risk-taking between the family companies in the home country to immigrant family company in the host country and (3) transforming process of innovativeness between the home and the host country.

  • 173.
    Falck, Ann-Christine
    et al.
    Chalmers University of Technology.
    Örtengren, Roland
    Chalmers University of Technology.
    Högberg, Dan
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    The Impact of Poor Assembly Ergonomics on Product Quality: A Cost-Benefit Analysis in Car Manufacturing2010In: Human Factors and Ergonomics in Manufacturing, ISSN 1090-8471, E-ISSN 1520-6564, Vol. 20, no 1, p. 24-41Article in journal (Refereed)
    Abstract [en]

    The study aimed at analyzing the relationship between assembly ergonomics, assemblability (“ease of assembly”), and product quality and at quantifying these relationships in economic terms. This was in order to better to support the development of more ergonomic product and assembly solutions, particularly at early stages of the car development process. The assembly of 24,443 cars was studied for 8 weeks in an assembly plant and for another 16 weeks as factory-complete vehicles. The results show increased risks for quality errors of 3.0 and 3.7 times and total action costs that were 8.7 times and 8.2 times higher for high and medium physical load assemblies compared to low physical load assemblies for 55 tasks assessed.

  • 174.
    Falck, Annki
    et al.
    Chalmers University of Technology.
    Örtengren, Roland
    Chalmers University of Technology.
    Högberg, Dan
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Early risk identification and cost-benefit analyses through ergonomics simulation2009Conference paper (Refereed)
    Abstract [en]

    For cost-beneficial reasons simulations with computer manikins have been increasingly used in the automotive industry for prediction of ergonomics problems before the product and work place exist in physical form. The main purpose of ergonomics simulations is to apply biomechanical models and data to assess the acceptability of the physical work load, e.g., working postures, visibility, clearance, etc., which could result in requirements to change the design of the product. The aim is to improve ergonomics conditions in manual assembly and to promote a better product quality through improved assemblability (ease of assembly). Many studies have shown a clear correlation between assembly ergonomics and product quality and that poor assembly ergonomics result in impaired product quality and in decreased productivity. Nevertheless, there are remaining difficulties in achieving acceptance for changes of product and production solutions because of poor assembly ergonomics.

    A recent study in the Swedish automotive industry showed that huge savings and increased profit margins can be obtained by eliminating ergonomics risk concepts in the very early product development process. The study confirmed a strong relation between poor ergonomics assembly solutions and quality errors of the product (car). There was a substantially increased risk for quality errors and increased costs for corrective measures of the product for assembly items of high and moderate physical work load compared to assembly items of low work load. The quality risk was increased 3 and 3.7 times, respectively. The overall cost for corrective measures in the assembly plant and for factory complete cars was 8.7 and 8.2 times higher for assembly items of high and medium physical work load compared to items of low physical work load.

    The purpose of this paper is to demonstrate the need for ergonomics simulations of potentially harmful assembly concepts in combination with cost-benefit analyses of conceivable system solutions based on calculation of costs for quality errors related to poor ergonomics and poor assemblability. The intended end result of this research is a model by application of which it is possible to calculate the cost for quality losses and health effects due to poor ergonomics and compare it with the cost for improving the ergonomics with designers, manufacturing engineers and ergonomists as main users.

  • 175.
    Fast-Berglund, Åsa
    et al.
    Chalmers University of Technology, Gothenburg, Sweden .
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Billing, Erik
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Palmquist, Adam
    Insert Coin, Gothenburg, Sweden.
    Romero, David
    Tecnologico de Monterrey, Mexico.
    Weichhart, Georg
    Profactor, Studgart, Austria.
    Conceptualizing Embodied Automation to Increase Transfer of Tacit knowledge in the Learning Factory2018In: Proceedings of IEEE 2018 International Conference on Intelligent Systems (IS), IEEE, 2018Chapter in book (Refereed)
    Abstract [en]

    This paper will discuss how cooperative agent-based systems, deployed with social skills and embodied automation features, can be used to interact with the operators in order to facilitate sharing of tacit knowledge and its later conversion into explicit knowledge. The proposal is to combine social software robots (softbots) with industrial collaborative robots (co-bots) to create a digital apprentice for experienced operators in human- robot collaboration workstations. This is to address the problem within industry that experienced operators have difficulties in explaining how they perform their tasks and later, how to turn this procedural knowledge (knowhow) into instructions to be shared among other operators. By using social softbots and co-bots, as cooperative agents with embodied automation features, we think we can facilitate the ‘externalization’ of procedural knowledge in human-robot interaction(s). This enabled by the capabilities of social cooperative agents with embodied automation features of continuously learning by looking over the shoulder of the operators, and documenting and collaborating with them in a non-intrusive way as they perform their daily tasks. 

  • 176.
    Fathi, Masood
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fontes, Dalila Benedita Machado Martins
    University of Porto, Portugal / INESC TEC, Porto, Portugal.
    Urenda Moris, Matias
    Jönköping University, Jönköping, Sweden / Uppsala University, Sweden.
    Ghobakhloo, Morteza
    University of Hormozgan, Bandar Abbas, Iran.
    Assembly line balancing problem: a comparative evaluation of heuristics and a computational assessment of objectives2018In: Journal of Modelling in Management, ISSN 1746-5664, E-ISSN 1746-5672, Vol. 13, no 2, p. 455-474Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this study is to firstly investigate the efficiency of the most commonly used performance measures for minimizing the Number of Workstations (NWs) in approaches addressing Simple Assembly Line Balancing Problem (SALBP) for both straight and U-shaped line. Secondly, this study aims to provide a comparative evaluation of 20 constructive heuristics to find solutions to the SALBP-1.

    Design/methodology/approach – 200 problems are solved by 20 different constructive heuristics for both straight and U-shaped assembly line. Moreover, several comparisons have been made to evaluate the performance of constructive heuristics.

    Findings – Minimizing the Smoothness Index (SI) is not necessarily equivalent to minimizing the NWs, therefore, it should not be used as the fitness function in approaches addressing the SALBP-1. Line efficiency (LE) and the idle time (IT) are indeed reliable performance measures for minimizing the NWs. The most promising heuristics for straight and U-shaped line configurations for SALBP-1 are also ranked and introduced.

    Practical implications – Results are expected to help scholars and industrial practitioners to better design effective solution methods for having a most balance assembly line. This study will further help with choosing the most proper heuristic with regard to the problem specifications and line configuration.

    Originality/value – There is limited research assessing the efficiency of the common objectives for SALBP-1. This study is among the first to prove that minimizing the workload smoothness is not equivalent to minimizing the NWs in SALBP-1 studies. This work is also one of the first attempts for evaluating the constructive heuristics for both straight and U-shaped line configurations.

  • 177.
    Fathi, Masood
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ghobakhloo, Morteza
    Department of Industrial Engineering, Minab Higher Education Center, University of Hormozgan, Bandar Abbas, Iran / Modern Technology Development and Implementation Research Center, University of Hormozgan, Bandar Abbas, Iran.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    An Interpretive Structural Modeling of Teamwork Training in Higher Education2019In: Education Sciences, E-ISSN 2227-7102, Vol. 9, no 1, p. 1-20Article in journal (Refereed)
    Abstract [en]

    In the past decade, the importance of teamwork training in higher education and employers’ enthusiasm for recruiting team players have been widely discussed in the literature. Yet, the process through which effective teamwork training is developed in a higher education setting has not yet been properly discussed. The present study aims to map the precedence relationships among the key determinants of teamwork training effectiveness and explain the process through which an effective teamwork training program can be developed. The study first conducted an extensive review of the literature to highlight the key determinants of effective teamwork training. Next, the study benefitted from an interpretive structural modeling technique and captured the opinions of a group of teamwork training experts to further map the interrelationships among the potential determinants that were identified. By listing the key determinants of effective teamwork training, mapping their interrelationships, and identifying their driving and dependence power, the present study is expected to help practitioners and academicians through providing a detailed understanding of the process through which an effective teamwork training program can be developed in a higher education context.

  • 178.
    Fathi, Masood
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Nourmohammadi, Amir
    Department of Industrial & Systems Engineering, Tarbiat Modares University, Tehran, Iran.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Assembly Line Balancing Type-E with Technological Requirement: A Mathematical Model2018In: 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: IOS Press, 2018, p. 183-188Conference paper (Refereed)
    Abstract [en]

    This study is motivated by a real-world assembly line in an automotive manufacturing company and it addresses the simple assembly line balancing problem type-E (SALBPE). The SALBPE aims to maximize the balance efficiency (BE) through determining the best combinations of cycle time and station number. To cope with the problem, a mixed integer nonlinear programming (MINLP) model is proposed. The MINLP model differs from the existing ALBPE models as it includes the technological requirements of assembly tasks and optimizes the variation of workload beside the BE. The validity of the proposed model is tested by solving the real-world case study and a set of benchmark problems.

  • 179.
    Fathi, Masood
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ghobakhloo, Morteza
    University of Hormozgan, Bandar Abbas, Iran.
    Eskandari, Hamidreza
    Tarbiat Modares University, Tehran, Iran.
    An optimization model for material supply scheduling at mixed-model assembly lines2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 6p. 1258-1263Article in journal (Refereed)
    Abstract [en]

    This study is motivated by a real case study and addresses the material supply problem at assembly lines. The aim of the study is to optimally schedule the delivery of raw material at assembly lines while using the minimum number of vehicles. To cope with the problem an original mixed integer linear programming model has been proposed based on the assumptions and constraints observed in the case study. The validity of the model has been examined by solving several real cases and analysing different scenarios. The results of the study show the efficiency and effectiveness of the model.

  • 180.
    Flores Garcia, Erik
    et al.
    Mälardalen University, Eskilstuna, Sweden.
    Ruiz Zúñiga, Enrique
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bruch, Jessica
    Mälardalen University, Eskilstuna, Sweden.
    Urenda Moris, Matias
    Division of Industrial Engineering and Management, University of Uppsala, Uppsala, Sweden.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Simulation-based Optimization for Facility Layout Design in Conditions of High Uncertainty2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 334-339Article in journal (Refereed)
    Abstract [en]

    Despite the increased use of Simulation based Optimization, the design of facility layout is challenged by high levels of uncertainty associatedwith new production processes. Addressing this issue, this paper aims to understand the conceptual modeling activities of Simulation-basedOptimization for facility layout design in conditions of high uncertainty. Based on three in-depth case studies, the results of this paper showhow characterization criteria of production systems can be used in conceptual modelling to reduce uncertainty. These results may be essentialto support managers and stakeholders during the introduction of new production processes in the design of facility layouts.

  • 181.
    Fornlöf, Veronica
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN Aerospace Engine Systems.
    Improved remaining useful life estimations for on-condition parts in aircraft engines2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on obtaining better estimates of remaining life for on-condition (OC) parts in aircraft engines. Aircraft engine components are commonly classified into three categories, life-limited parts (LLP), OC-parts and consumables. Engine maintenance typi-cally accounts for 10% to 20% of aircraft-related operating cost. Current methods to esti-mate remaining life for OC parts have been found insufficient and this thesis aims to devel-op a method that obtains better life estimates of OC part. Improved life estimates are es-sential to facilitate more reliable maintenance plans and lower maintenance costs. In the thesis, OC parts that need a better life estimates are identified and suitable prognosis methodologies for estimating the remaining life are presented.

    Three papers are appended to the thesis. The first paper lays out the main principles of air-craft engine maintenance and identifies the potential for improving maintenance planning by improving the remaining life estimation for the OC parts. The paper concludes that re-search is needed to find better estimates so that the right amount of maintenance is per-formed at each maintenance occasion.

    The second paper describes the aircraft and its engine from a system of system perspective. The aim of the paper is to show that no system is stronger than its weakest part and that there is a potential to increase the availability and readiness of the complete system, the aircraft engine, by introducing better life estimates for OC parts. Furthermore, a review of all engine parts, no matter if they are life-limited or on-condition, which needs to be incor-porated in a replacement model for maintenance optimization, is given. The paper con-cludes that the reliability of the complete aircraft engine would be increased if better life estimates are presented also for the OC parts.

    The third paper includes an evolved analysis of the subject and the analysis moves deeper in to a subsystem/module of the engine, the low pressure turbine. The specific subsys-tem/module is further analyzed to show the potential of increased reliability for the subsys-tem/module and the complete system, the aircraft engine, if better life estimates for the OC parts are obtained. Methods on how to estimate remaining life is discussed in this paper. It is stated that life estimates can be based on visual inspections, available testing methods (e.g. non destructive testing ) or new techniques that may be need to be developed based on remaining useful life estimations. To estimate the remaining life for the OC parts well es-tablished prognostic techniques such as physic-based, data-driven, symbolic, hybrid, or context awareness approaches that combine contextual/situation information awareness will be considered.

  • 182.
    Fornlöf, Veronica
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN Aerospace.Engine Systems.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Almgren, Torgny
    GKN Aerospace Engine Systems.
    Aircraft engines: A maintenance trade-off in a complex system2015Conference paper (Refereed)
    Abstract [en]

    An aircraft engine is a system of systems with several degrees of complexity. It is important to perform the correct amount of maintenance at each individual maintenance event. A mathematical replacement model is used to ensure that the correct amount of maintenance is performed. However, this paper shows that the reliability of this model could be improved if there were a better way to estimate the life length of on-condition maintained engine parts.

  • 183.
    Fornlöf, Veronica
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN Aerospace.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Luleå University of Technology.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Almgren, Torgny
    GKN Aerospace.
    On-Condition Parts versus life limited parts: A trade off in aircraft engines2016In: Current Trends in Reliability, Availability, Maintainability and Safety: An Industry Perspective / [ed] U. Kumar, A. Ahmadi, A. K. Verma & P. Varde, 2016, p. 253-262Conference paper (Refereed)
  • 184.
    Fornlöf, Veronica
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Almgren, Torgny
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    RUL estimation and maintenance optimization for aircraft engines: A system of system approach2016In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 7, no 4, p. 450-461Article in journal (Refereed)
    Abstract [en]

    An aircraft engine is a system of systems with several degrees of complexity. It is important to perform the correct amount of maintenance at each individual maintenance event. A mathematical replacement model is used to ensure that the correct maintenance is performed. The reliability of the results from the mathematical replacement model will be improved if there is a better way to estimate the life length for on-condition engine parts.

  • 185.
    Fornlöf, Veronica
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Almgren, Torgny
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Catelani, Marcantonio
    Department of Information Engineering, University of Florence, Florence, Italy.
    Ciani, Lorenzo
    Department of Information Engineering, University of Florence, Florence, Italy.
    Maintenance, prognostics and diagnostics approaches for aircraft engines2016In: 3rd IEEE International Workshop on Metrology for Aerospace, MetroAeroSpace 2016: Proceedings, IEEE, 2016, p. 403-407Conference paper (Refereed)
    Abstract [en]

    In avionics application one of the most important competition factors is the reliability, given that the failure occurrence may leads to a critical state for the functioning of the aircraft. Different maintenance, prognostics and diagnostics approaches are possible with the final aim to optimize both system's availability and safety. Aircraft engines represent a safety critical part of the airplane. For this reason it is a key issue to allocate the proper amount of maintenance at each individual maintenance event. In this paper a mathematical replacement model is proposed to guarantee that the correct amount of maintenance is performed.

  • 186.
    Fornlöf, Veronica
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN.
    Sandberg, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Almgren, Torgny
    GKN Aerospace Engine Systems.
    More reliable aircraft engine maintenance optimization by a classification framework for on-condition parts2014In: Proceedings of the 6th Swedish Production Symposium, SPS14, Gothenburg, Sweden, Chalmers , 2014Conference paper (Refereed)
  • 187.
    Frantzén, Marcus
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    A real-time simulation-based optimisation environment for industrial scheduling2013Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In order to cope with the challenges in industry today, such as changes in product diversity and production volume, manufacturing companies are forced to react more flexibly and swiftly. Furthermore, in order for them to survive in an ever-changing market, they also need to be highly competitive by achieving near optimal efficiency in their operations. Production scheduling is vital to the success of manufacturing systems in industry today, because the near optimal allocation of resources is essential in remaining highly competitive.

     

    The overall aim of this study is the advancement of research in manufacturing scheduling through the exploration of more effective approaches to address complex, real-world manufacturing flow shop problems. The methodology used in the thesis is in essence a combination of systems engineering, algorithmic design and empirical experiments using real-world scenarios and data. Particularly, it proposes a new, web services-based, industrial scheduling system framework, called OPTIMISE Scheduling System (OSS), for solving real-world complex scheduling problems. OSS, as implemented on top of a generic web services-based simulation-based optimisation (SBO) platform called OPTIMISE, can support near optimal and real-time production scheduling in a distributed and parallel computing environment. Discrete-event simulation (DES) is used to represent and flexibly cope with complex scheduling problems without making unrealistic assumptions which are the major limitations of existing scheduling methods proposed in the literature.  At the same time, the research has gone beyond existing studies of simulation-based scheduling applications, because the OSS has been implemented in a real-world industrial environment at an automotive manufacturer, so that qualitative evaluations and quantitative comparisons of scheduling methods and algorithms can be made with the same framework.

     

    Furthermore, in order to be able to adapt to and handle many different types of real-world scheduling problems, a new hybrid meta-heuristic scheduling algorithm that combines priority dispatching rules and genetic encoding is proposed. This combination is demonstrated to be able to handle a wider range of problems or a current scheduling problem that may change over time, due to the flexibility requirements in the real-world.  The novel hybrid genetic representation has been demonstrated effective through the evaluation in the real-world scheduling problem using real-world data.

  • 188.
    Frantzén, Marcus
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Holm, Magnus
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    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.
    Karlsson, V.
    Volvo Group Trucks Operations, Powertrain Production Skövde, Skövde, Sweden.
    Bremert, M.
    Volvo Group Trucks Operations, Powertrain Production Skövde, Skövde, Sweden.
    Dynamic maintenance priority of a real-world machining line2016In: Proceedings of the 7th Swedish Production Symposium, 2016Conference paper (Refereed)
    Abstract [en]

    To support the shop-floor operators, decision support systems (DSS) are becoming more and more vital to the success of manufacturing systems in industry today. In order to get a DSS able to adapt to disturbances in a production system, on-line data are needed to be able to make optimal or near-optimal decisions in real-time (soft real-time). This paper investigates one part of such a system, i.e. how different priorities of maintenance activities (planned and unplanned) affect the productivity of a production system. A discrete-event simulation model has been built for a real-world machining line in order to simulate the decisions made in subject to disturbances. This paper presents a way of prioritizing operators and machines based on multiple criteria such as competence, utilization, distance, bottleneck, and Work-In-Process. An experimental study based on the real-world production system has shown promising results and given insights of how to prioritize the operators in a good way. Another novelty introduced in this paper is the use of simulation-based optimization to generate composite dispatching rules in order to find good tradeoffs when taking a decision of which machine or operator to select.

  • 189.
    Frantzén, Marcus
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    A case study of applying simulation-based optimisation to a real-world scheduling problem2010In: ORbit, ISSN 1601-8893, no 17, p. 4-7Article in journal (Other (popular science, discussion, etc.))
  • 190.
    Frantzén, Marcus
    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.
    Production simulation education using rapid modeling and optimization: Successful studies2015In: 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, Piscataway, NJ: IEEE Press, 2015, p. 3526-3537Conference paper (Refereed)
    Abstract [en]

    A common issue facing many simulation educators is that students usually spend excessive time to struggle with the programming and statistic parts of the simulation courses, and simply very little time to learn running systems analysis. If the students are coming from industry, and not the campus, then the problem becomes even worse. We observed this problem around 2005 and started to develop a new simulation software, a factory conceptual design toolset, partly aimed to address this problem. A new set of educational courses has since then been developed around the software for teaching production systems analysis, with both the campus students and managers/engineers from industry in mind. In this paper, we briefly introduce the software and share our experiences and some representative, successful studies conducted by the students in the past years.

  • 191.
    Frantzén, Marcus
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Ng, Amos H. C.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Moore, Philip
    Computing Sciences and Engineering, De Montfort University Leicester, LE1 9BH, United Kingdom.
    A simulation-based scheduling system for real-time optimization and decision making support2011In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 27, no 4, p. 696-705Article in journal (Refereed)
    Abstract [en]

    This paper presents an industrial application of simulation-based optimization (SBO) in the scheduling and real-time rescheduling of a complex machining line in an automotive manufacturer in Sweden. Apart from generating schedules that are robust and adaptive, the scheduler must be able to carry out rescheduling in real time in order to cope with the system uncertainty effectively. A real-time scheduling system is therefore needed to support not only the work of the production planner but also the operators on the shop floor by re-generating feasible schedules when required. This paper describes such a real-time scheduling system, which is in essence a SBO system integrated with the shop floor database system. The scheduling system, called OPTIMISE scheduling system (OSS), uses real-time data from the production line and sends back expert suggestions directly to the operators through Personal Digital Assistants (PDAs). The user interface helps in generating new schedules and enables the users to easily monitor the production progress through visualization of production status and allows them to forecast and display target performance measures. Initial results from this industrial application have shown that such a novel scheduling system can help both in improving the line throughput efficiently and simultaneously supporting real-time decision making.

  • 192.
    Galar, Diego
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Luleå University of Technology, Luleå, Sweden.
    Kans, Mirka
    Linnaeus University, Kalmar, Sweden.
    Schmidt, Bernard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Big Data in Asset Management: Knowledge Discovery in Asset Data by the Means of Data Mining2016In: Proceedings of the 10th World Congress on Engineering Asset Management (WCEAM 2015) / [ed] Kari T. Koskinen, Helena Kortelainen, Jussi Aaltonen,Teuvo Uusitalo, Kari Komonen, Joseph Mathew, Jouko Laitinen, Springer, 2016, p. 161-171Conference paper (Refereed)
    Abstract [en]

    Assets are complex mixes of complex systems, built from components which, over time, may fail. The ability to quickly and efficiently determine the cause of failures and propose optimum maintenance decisions, while minimizing the need for human intervention is necessary. Thus, for complex assets, much information needs to be captured and mined to assess the overall condition of the whole system. Therefore the integration of asset information is required to get an accurate health assessment of the whole system, and determine the probability of a shutdown or slowdown. Moreover, the data collected are not only huge but often dispersed across independent systems that are difficult to access, fuse and mine due to disparate nature and granularity. If the data from these independent systems are combined into a common correlated data source, this new set of information could add value to the individual data sources by the means of data mining. This paper proposes a knowledge discovery process based on CRISP-DM for failure diagnosis using big data sets. The process is exemplified by applying it on railway infrastructure assets. The proposed framework implies a progress beyond the state of the art in the development of Big Data technologies in the fields of Knowledge Discovery algorithms from heterogeneous data sources, scalable data structures, real-time communications and visualizations techniques.

  • 193.
    Gandhi, Kanika
    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.
    Machine maintenance decision support system: A systematic literature review2018In: 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, Skövde, Sweden / [ed] Peter Thorvald, Keith Case, Amsterdam: IOS Press, 2018, p. 349-354Conference paper (Refereed)
    Abstract [en]

    Growing competition market situations have emerged the requirement of the real-time data, understanding data behaviour, and maintenance actions in the manufacturing system. The future decision-making process in manufacturing needs to be more flexible to adapt to various methods for maintenance decision support systems (MDSS). This paper classifies various application areas of MDSS through a systemic literature review. Specifically, it identifies the relationship between the machine maintenance areas and the processes in which it integrates different tools and techniques to develop MDSS. The accumulated information helps in analyzing trends and shortcomings to concentrate the efforts for future research work. The reviewed papers are selected based on the contents, application tool assessments and clustered by their application areas. Furthermore, it proposes a structure outlined based on the functional knowledge as well as the information flow design during the development of MDSS, along with the relationship among application areas.

  • 194.
    Gandhi, Kanika
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Schmidt, Bernard
    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.
    Towards data mining based decision support in manufacturing maintenance2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 261-265Article in journal (Refereed)
    Abstract [en]

    The current work presents a decision support system architecture for evaluating the features representing the health status to predict maintenance actions and remaning useful life of component. The evaluation is possible through pattern analysis of past and current measurements of the focused research components. Data mining visualization tools help in creating the most suitable patterns and learning insights from them. Estimations like features split values or measurement frequency of the component is achieved through classification methods in data mining. This paper presents how the quantitative results generated from data mining can be used to support decision making of domain experts.

  • 195.
    García-García, Daniel
    et al.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alicante, Spain.
    Balart, Rafael
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alicante, Spain.
    Lopez-Martinez, Juan
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alicante, Spain.
    Ek, Monica
    School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Fibre and Polymer Technology, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Moriana, Rosana
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Fibre and Polymer Technology, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Optimizing the yield and physico-chemical properties of pine cone cellulose nanocrystals by different hydrolysis time2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 5, p. 2925-2938Article in journal (Refereed)
    Abstract [en]

    Cellulose nanocrystals (CNCs) were isolated for the first time from pine cones (PC) by alkali and bleaching treatments and subsequent sulfuric acid hydrolysis (64%) at 45 degrees C. The influence of the hydrolytic reaction time (30, 45, and 90 min) on the yield, chemical composition and structure, and thermal stability of CNCs was evaluated. The removal of non-cellulosic constituents during the alkaline and bleaching treatment resulted in high pure cellulosic fibres. The isolation of CNCs from these cellulosic fibres at different reaction times was verified by the nano-dimensions of the individual crystals (< 3 and < 335 nm of average diameter and length, respectively). The highest yield (15%) and the optimum CNCs properties in terms of aspect ratio, thermal stability and crystallinity were obtained for an extraction time of 45 min. PC appeared to be a new promising source of cellulose fibres and CNCs with potential to be applied as reinforcement in composites and for food-packaging.

  • 196.
    García-García, Daniel
    et al.
    Instituto de Tecnología de Materiales-ITM, Universitat Politècnica de València, Alicante, Spain.
    Lopez-Martínez, Juan
    Instituto de Tecnología de Materiales-ITM, Universitat Politècnica de València, Alicante, Spain.
    Rafael, Balart
    Instituto de Tecnología de Materiales-ITM, Universitat Politècnica de València, Alicante, Spain.
    Strömberg, Emma
    School of Engineering Science in Chemistry, Biotechnology and Health, Department of Fibre and Polymer Technology, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Moriana, Rosana
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. School of Engineering Science in Chemistry, Biotechnology and Health, Department of Fibre and Polymer Technology, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend2018In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 104, p. 10-18Article in journal (Refereed)
    Abstract [en]

    In this work, different loads (3, 5 and 7 wt%) of pine cone cellulose nanocrystals (CNCs) were added to films ofpoly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) blends with a composition of 75 wt% PHB and 25 wt% PCL (PHB75/PCL25). The films were obtained after solvent casting followed by melt compounding in anextruder and finally subjected to a thermocompression process. The influence of different CNCs loadings on themechanical, thermal, optical, wettability and disintegration in controlled compost properties of the PHB75/PCL25blend was discussed. Field emission scanning electron microscopy (FESEM) revealed the best dispersion of CNCson the polymeric matrix was at a load of 3 wt%. Over this loading, CNCs aggregates were formed enhancing thefilms fragilization due to stress concentration phenomena. However, the addition of CNCs improved the opticalproperties of the PHB75/PCL25films by increasing their transparency and accelerated the film disintegration incontrolled soil conditions. In general, the blend with 3 wt% CNCs offers the best balanced properties in terms ofmechanical, thermal, optical and wettability

  • 197.
    Gerdes, M.
    et al.
    Hamburg Univ Appl Sci, Aeroaircraft Design & Syst Grp, Hamburg, Germany..
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Luleå Univ Technol, Div Operat & Maintenance Engn, Luleå, Sweden.
    Scholz, D.
    Hamburg Univ Appl Sci, Aeroaircraft Design & Syst Grp, Hamburg, Germany.
    Genetic algorithms and decision trees for condition monitoring and prognosis of A320 aircraft air conditioning2017In: International Journal of Condition Monitoring, ISSN 1354-2575, E-ISSN 1754-4904, Vol. 59, no 8, p. 424-433Article in journal (Refereed)
    Abstract [en]

    Unscheduled maintenance is a large cost driver for airlines, but condition monitoring and prognosis can reduce the number of unscheduled maintenance actions. This paper discusses how condition monitoring can be introduced into most systems by adopting a data-driven approach and using existing data sources. The goal is to forecast the remaining useful life (RUL) of a system based on various sensor inputs. Decision trees are used to learn the characteristics of a system. The data for the decision tree training and classification are processed by a generic parametric signal analysis. To obtain the best classification results for the decision tree, the parameters are optimised by a genetic algorithm. A forest of three different decision trees with different signal analysis parameters is used as a classifier. The proposed method is validated with data from an A320 aircraft from Etihad Airways. Validation shows that condition monitoring can classify the sample data into ten predetermined categories, representing the total useful life (TUL) in 10% steps. This is used to predict the RUL. There are 350 false classifications out of 850 samples. Noise reduction reduces the outliers to nearly zero, making it possible to correctly predict condition. It is also possible to use the classification output to detect a maintenance action in the validation data.

  • 198.
    Gerdes, Mike
    et al.
    Aero - Aircraft Design and Systems Group, Hamburg University of Applied Sciences, Hamburg, Germany.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Division of Operation and Maintenance Engineering, Luleå University of Technology, Luleå, Sweden.
    Fuzzy condition monitoring of recirculation fans and filters2016In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 7, no 4, p. 469-479Article in journal (Refereed)
    Abstract [en]

    A reliable condition monitoring is needed to be able to predict faults. Pattern recognition technologies are often used for finding patterns in complex systems. Condition monitoring can also benefit from pattern recognition. Many pattern recognition technologies however only output the classification of the data sample but do not output any information about classes that are also very similar to the input vector. This paper presents a concept for pattern recognition that outputs similarity values for decision trees. Experiments confirmed that the method works and showed good classification results. Different fuzzy functions were evaluated to show how the method can be adapted to different problems. The concept can be used on top of any normal decision tree algorithms and is independent of the learning algorithm. The goal is to have the probabilities of a sample belonging to each class. Performed experiments showed that the concept is reliable and it also works with decision tree forests (which is shown during this paper) to increase the classification accuracy. Overall the presented concept has the same classification accuracy than a normal decision tree but it offers the user more information about how certain the classification is.

  • 199.
    Gerdes, Mike
    et al.
    Hamburg University of Applied Sciences Aero - Aircraft Design and Systems Group, Hamburg, Germany / Luleå University of Technology, Division of Operation and Maintenance Engineering, Luleå, Sweden.
    Galar, Diego
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Luleå University of Technology, Division of Operation and Maintenance Engineering, Luleå, Sweden.
    Scholz, Dieter
    Hamburg University of Applied Sciences Aero - Aircraft Design and Systems Group, Hamburg, Germany.
    Decision Trees and the Effects of Feature Extraction Parameters for Robust Sensor Network Design2017In: Eksploatacja i Niezawodnosc - Maintenance and Reliability, ISSN 1507-2711, Vol. 19, no 1, p. 31-42Article in journal (Refereed)
    Abstract [en]

    Reliable sensors and information are required for reliable condition monitoring. Complex systems are commonly monitored by many sensors for health assessment and operation purposes. When one of the sensors fails, the current state of the system cannot be calculated in same reliable way or the information about the current state will not be complete. Condition monitoring can still be used with an incomplete state, but the results may not represent the true condition of the system. This is especially true if the failed sensor monitors an important system parameter. There are two possibilities to handle sensor failure. One is to make the monitoring more complex by enabling it to work better with incomplete data; the other is to introduce hard or software redundancy. Sensor reliability is a critical part of a system. Not all sensors can be made redundant because of space, cost or environmental constraints. Sensors delivering significant information about the system state need to be redundant, but an error of less important sensors is acceptable. This paper shows how to calculate the significance of the information that a sensor gives about a system by using signal processing and decision trees. It also shows how signal processing parameters influence the classification rate of a decision tree and, thus, the information. Decision trees are used to calculate and order the features based on the information gain of each feature. During the method validation, they are used for failure classification to show the influence of different features on the classification performance. The paper concludes by analysing the results of experiments showing how the method can classy different errors with a 75% probability and how different feature extraction options influence the information gain.

  • 200.
    Ghobakhloo, Morteza
    et al.
    Department of Industrial Engineering, Minab Higher Educational Center, University of Hormozgan, Bandar Abbas, Iran.
    Azar, Adel
    Department of Management and Economics, Tarbiat Modares University, Tehran, Iran.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Lean-green manufacturing: the enabling role of information technology resource2018In: Kybernetes, ISSN 0368-492X, E-ISSN 1758-7883, Vol. 47, no 9, p. 1752-1777Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to contribute to the existing knowledge about the relationships between information technology (IT), lean manufacturing (LM), organizational environmental issues and business performance.

    Design/methodology/approach – A questionnaire-based survey was conducted to collect data from 122 elite manufacturers, and the hypothesized relationships were tested using partial least squares structural equation modeling. Findings – IT competence in LM acts as a lower-order organizational capability, and its business value should be recognized through the intermediate roles of LM effectiveness and environmental management capability. Findings recommend that the net benefits of LM are mainly materialized through waste and pollution reduction and simplified implementation of proactive environmental practices.

    Research limitations/implications – Among other limitations, relying on a rather small sample size and cross-sectional data of this research, and lack of generalizability of findings, tends to have certain limitations. An interesting direction for future research would be to extend this research by assessing interaction of other types of IT resources with LM and organizational environmental issues.

    Practical implications – Both LM and proactive environmental management are information-intensive. Investment in both technological and human aspects of IT resource aimed at increasing the effectiveness of LM activities and proactive environmental practices is imperative for contemporary manufacturers.

    Originality/value – This study introduces the IT capability of IT competence in LM and two organizational capabilities of LM effectiveness and environmental management capability. By doing so, the study highlights the significant role of organizational environmental issues in devising firms’ IT and advanced manufacturing technology investment strategies in LM context.

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