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  • 1.
    Adelakun, Olawale
    University West, Department of Economics and IT.
    The Role of Business Intelligence in Government: A Case Study of a Swedish Municipality Contact Center2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    The aim of this study is to investigate the role Business Intelligence (BI) can play in government and more specifically at the municipality level. The study aims to investigate how data collected from a municipality Contact Center can be leveraged with the help of a BI solution. The study focuses on the Contact Center at Järfälla Kommun (municipality) and investigates whether a BI implementation can help to realize more effective planning, resource allocation and improved services and e-services. Municipality Contact Centers are becoming an increasingly popular precedent providing municipal residents with a centralized service where they can make inquiries, provide information, lodge complaints or commend actions related to activities within the specific municipality. BI can turn raw data into concrete figures and reports, map patterns and trends and support effective decision making. It can also however be costly and difficult to integrate and face resistance due to perceived complexity. This paper aims to take such notions into consideration and investigate the feasibility of implementing such a solution in the context of a municipality Contact Center.

    This paper identifies various benefits and drawbacks from literature which are then modeled into a SWOT framework. In addition, semi-structured interviews are utilized in this study and targeted at stakeholders knowledgeable in the Contact Center, BI, or both. Findings from the SWOT framework will be measured against the findings from the interviews and an analysis of correlations between the two sources will be investigated.

  • 2.
    Alizadeh-Khameneh, Mohammad Amin
    et al.
    Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Sjöberg, Lars
    Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), Stockholm, Sweden.
    The Effect of Instrumental Precision on Optimisation of Displacement Monitoring Networks2016In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 51, no 4, p. 761-772Article in journal (Refereed)
    Abstract [en]

    In order to detect the geo-hazards, different deformation monitoring networks are usually established. It is of importance to design an optimal monitoring network to fulfil the requested precision and reliability of the network. Generally, the same observation plan is considered during different time intervals (epochs of observation). Here, we investigate the case that instrumental improvements in sense of precision are used in two successive epochs. As a case study, we perform the optimisation procedure on a GPS monitoring network around the Lilla Edet village in the southwest of Sweden. The network was designed for studying possible displacements caused by landslides. The numerical results show that the optimisation procedure yields an observation plan with significantly fewer baselines in the latter epoch, which leads to saving time and cost in the project. The precision improvement in the second epoch is tested in several steps for the Lilla Edet network. For instance, assuming two times better observation precision in the second epoch decreases the number of baselines from 215 in the first epoch to 143 in the second one.

  • 3.
    Bernhard, Irene
    University West, Department of Economics and IT, Division of Media and Design.
    Incentives for Inclusive e-Government: The Implementation of Contact Centers in Swedish Municipalities2015In: Digital Solutions for Contemporary Democracy and Government / [ed] Bwalya, Kelvin Joseph & Mutula, Stephen, IGI Global, 2015, 1, p. 304-327Chapter in book (Refereed)
  • 4.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Process and Product Development.
    Evaluation of a method to radiometric calibrate hot target image data by using simple reference sources close to ambient temperatures2010In: Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXI / [ed] Gerald C. Holst, Keith A. Krapels, 2010Conference paper (Other academic)
    Abstract [en]

    To perform radiometric calibrations of image data, reference sources are needed in order to acquire data at two or more radiance levels giving the calibration parameters. Due to sensor drift for detectors in the infrared region the parameters have to be frequently recalculated during an extended signature measurement if the accuracy is to be maintained. In signature measurements where the incident radiance levels from hot targets are exceeding the background by many orders of magnitude the reference sources need to emit radiation at high radiance levels. Such reference sources are more complex and so is the handling of these sources. The calibration procedure tends to become impractical in field trials where several spectral bands are involved, which increases the need for reference data and the number of reference sources. A method to radiometric calibrate hotspot target data by using only a few simple reference sources close to ambient temperatures has been evaluated in this paper. Reference data has been collected both in laboratory studies and in field trials at various weather conditions. The accuracy and the precision of the method are presented. The uncertainty due to sensor drift is estimated. Error sources connected to the calibration method are discussed.

  • 5.
    Bäckman, Kjell
    University West, Department of Economics and IT, Divison of Informatics.
    Automatic fitness in generative jazz soloimprovisation2012In: EIMAS 2012 Conference Proceedings, Juiz de Fora, Brazil, 2012, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Recent work by the author has revealed the need for an automatic fitness function in the evolutionary algorithm

    for generation of jazz solos. A computer based automatic fitness function enables greater populations and a great

    number of generations within a manageable time. This paper describes how the automatic fitness function is

    implemented using score calculation based on specific events recognized in the solo line The evaluation function

    is based on the author’s solo analysis of 73 great masters’ solo characteristics and their techniques used for buildup

    of jazz solos.

  • 6.
    Choquet, Isabelle
    University West, Department of Informatics and Mathematics.
    Nozzle exit geometry and lump formation in atmospheric plasma spraying2005In: International Thermal Spray Conference: Basel, Switzerland, May, ASM International , 2005, p. 259-264Conference paper (Other academic)
    Abstract [en]

    Plasma spraying operations performed with high carrier gas flow rate may improve the coating properties but they can also lead to lump formation and thus coating defects. The damaged work piece must then be stripped and re-coated, which implies a considerable waste in terms of coating powder, energy and time. The aim of this study was to determine the cause of the lumps, and propose process modifications for avoiding their formation while keeping the coating quality. Numerical simulations based on 3D turbulent Navier-Stokes equations in local thermal and chemical equilibrium were carried out to understand the problem and estimate the feasibility of the proposed solutions. The computational results were supplemented by experiments for validation. A first set of investigations was focused on the location and orientation of the powder port injector. It turned out that it was not possible to keep the coating quality while avoiding lump formation by simply moving the powder injector. A new geometry of the nozzle exit was then designed and successfully tested for a first application with Ni-5Al powder used in production. 

  • 7.
    Choquet, Isabelle
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Wigren, J
    Deposition Rate Increase in APS Processes by Means of Multiple Injection Ports2004In: Thermal Spray 2004: Advances in Technology and Application: Proceedings of the International Thermal Spray Conference 10–12 May 2004, Osaka, Japan, 2004, p. 691-695Conference paper (Other academic)
  • 8.
    Curry, Nicholas
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Li, Xin-Hai
    Tricoire, Aurelien
    Dorfman, Mitchell
    Next Generation Thermal Barrier Coatings for the Gas Turbine Industry2010In: Proceedings of the Thermal Spray: Global Solutions for Future Application (ITSC 2010) Conference: Singapore, May 3-5, 2010, 2010, p. 716-722Conference paper (Refereed)
  • 9.
    Danielsson, Fredrik
    et al.
    University West, Department of Technology.
    Ericsson, Mikael
    University West, Department of Technology.
    Computer Aided Robotics combined with a Finite Element Analysis for Process Simulation of Welding2004In: 35th International Symposium on Robotics, ISR 2004: Paris, mars 2004, Paris: International Federation of Robotics , 2004Conference paper (Refereed)
  • 10.
    Edstorp, Marcus
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Eriksson, Kenneth
    University West, Department of Technology, Mathematics and Computer Science.
    Modelling and Simulation of Moving Boundaries and Convective Heat Transfer in Non-Autogenous Fusion Weld Pools using FEMLAB 3.12005In: Proceedings of the FEMLAB CONFERENCE 2005, 2005, p. 85-90Conference paper (Other academic)
  • 11.
    Emanuelsson, Andreas
    et al.
    University West, Department of Engineering Science.
    Paavilainen, Roger
    University West, Department of Engineering Science.
    Inventering och riskanalys av skolskjutshållplatser: kvalitetsäkring med avseende på trafiksäkerhet2010Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Trollhättan municipality approximately 700 school bus stops are in service. To ensure high quality of the performance of school bus operations, with focus on traffic safety, it was decided to conduct a survey of bus stops including assessments of risks.

    This master thesis aims to identify the factors affecting road safety at bus stops and pedestrian connections, and to conduct an inventory and analysis of selected sites in Trollhättan municipality. The work also aims to show examples of how risk assessment should be performed in future studies. A risk analysis model provided by the Swedish Transport Administration is supplemented and used in a field study. The risk assessment is based on, inter alia, traffic flow, visibility distance, lighting, speed of traffic and the presence of bus shelter. A total number of 93 bus stops and 228 pedestrian connections are examined during the field study. The result shows that the connections are generally a larger traffic safety problem than the bus stops.

    The risk analysis model uses both objective and subjective assessments. Applying subjective assessments to supplement objective is beneficial, but there are some difficulties in making subjective judgments. Those require that the evaluator possess much knowledge and experience in traffic safety and it is difficult to always be consistent when setting subjective ratings.

    The group recommends the city of Trollhättan to proceed with field testing of bus stops and pedestrian connections, and to regularly conduct surveys of passenger’s experiences and views on safety. Furthermore it is recommended that the bus drivers carry out a risk analysis from their perspective.

  • 12.
    Ericsson, Mikael
    University West, Department of Technology, Mathematics and Computer Science.
    Simulation fo Robot Paths and Heat Effects in Welding2006Doctoral thesis, comprehensive summary (Other academic)
  • 13.
    Ericsson, Mikael
    University West, Department of Technology.
    Simulation of robotic TIG-welding2003Licentiate thesis, comprehensive summary (Other academic)
  • 14.
    Ericsson, Mikael
    et al.
    University West, Department of Technology, Mathematics and Computer Science. University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Berglund, D.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science. University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Three Dimensional Simulation of Robot path, Heat Transfer and Residual Stresses of a TIG-welded Part with Complex Geometry2002In: Trends in Welding Research: Proceedings of the 6th International Conference: Phoenix, AZ, 15-19 April, 2002, 2002, p. 973-978Conference paper (Other academic)
    Abstract [en]

    In this paper a system is presented that combines a robot off-line programming software with a finite element model that predicts temperature-time histories and residual stress distributions. The objective is to develop a tool for the engineer where robot trajectories and welding process parameters can be optimized on parts with complex geometry. The system was evaluated on a stainless steel gas turbine component. Robot weld paths were defined off-line and automatically downloaded to the finite element program, where transient temperatures and residual stresses were predicted. Temperature dependent properties and phase change, were included in the analysis. Assumptions and principles behind the modeling techniques are presented together with predicted temperature histories, residual stresses, and fixture forces.

  • 15.
    Ericsson, Mikael
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Henriksson, P.
    Non-contact Temperature Measurements using an Infrared Camera in Aerospace Welding Applications2002In: 6th International Conference on Trends in Welding Research: Phoenix, AZ; 15-19 April 2002, Materials Park: ASM International , 2002, p. 930-935Conference paper (Refereed)
    Abstract [en]

    This paper describes the application of infrared (IR) thermal imaging and temperature measurements in welding applications, both on single plane plates and on an aero engine turbine component with complex geometry. Temperature profiles were measured on the plates using thermocouples (T/C) in combination with an IR camera system, and the results were compared. The IR camera was used both in line scan mode (270 Hz scan frequency) and in full frame mode (1 Hz frame rate). Different methods of surface treatments have been tested to handle the problem of the surface emissivity variations due to oxidation during welding. Results from measurements using thermocouples and IR camera is presented in the paper as well as temperature measurements using the IR camera on an turbine exhaust case (TEC) engine component.

  • 16.
    Ericsson, Mikael
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science.
    Berglund, D.
    Ling-Peng, R.
    Three dimensional simulation of robot path, heat transfer and residual stresses of a welded part with complex geometry2005In: International jourrnal for the joining of materials, ISSN 0905-6866, Vol. 17, no 2, p. 42-51Article in journal (Refereed)
    Abstract [en]

    In this article a simulation system is presented that combines computer aided robotics software used to define the welding operation, with a finite element model that predicts temperature-time histories and residual stress distributions for welding applications. The objective is to develop a tool for engineering processes in which robot trajectories and welding process parameters can be optimized off-line on parts with complex geometries. The system was evaluated on a stainless steel gas turbine component. Temperature dependent properties and phase change were included in the analysis. The turbine component was welded using an in-house TIG welding cell. The assumptions and principles that underpin the modeling techniques are presented together with predicted temperature histories, residual stresses, and fixture forces. Predicted residual stresses were compared with neutron diffraction measurements.

  • 17.
    Ericsson, Mikael
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Ryberg, Anders
    Nilsson, Jim
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers.
    Off-Line Simulation of Advanced Stereo Vision Welding Applications2010In: Machine Vision and Applications, ISSN 0932-8092, E-ISSN 1432-1769Article in journal (Refereed)
  • 18.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering. Division of Geodesy, Royal Institute of Technology, Stockholm, Sweden.
    Lars E., Sjöberg
    Division of Geodesy, Royal Institute of Technology, Stockholm, Sweden.
    Ramin, Kiamehr
    Department of Geodesy and Geomatics, Zanjan University, Zanjan, Iran.
    Evaluation of robust techniques in suppressing the impact of outliers in a deformation monitoring network – A case study on the Tehran Milad tower network2007In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 42, no 4, p. 449-463Article in journal (Refereed)
    Abstract [en]

    The problem of handling outliers in a deformation monitoring network is of special importance, because the existence of outliers may lead to false deformation parameters. One of the approaches to detect the outliers is to use robust estimators. In this case the network points are computed by such a robust method, implying that the adjustment result is resisting systematic observation errors, and, in particular, it is insensitive to gross errors and even blunders. Since there are different approaches to robust estimation, the resulting estimated networks may differ. In this article, different robust estimation methods, such as the M-estimation of Huber, the “Danish”, and the L 1-norm estimation methods, are reviewed and compared with the standard least squares method to view their potentials to detect outliers in the Tehran Milad tower deformation network. The numerical studies show that the L 1-norm is able to detect and down-weight the outliers best, so it is selected as the favourable approach, but there is a lack of uniqueness. For comparison, Baarda’s method “data snooping” can achieve similar results when the outlier magnitude of an outlier is large enough to be detected; but robust methods are faster than the sequential data snooping process.

  • 19.
    Fasth, Angelica
    et al.
    University West, Department of Engineering Science.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science.
    Musalek, Radek
    Characterization of thermo-mechanical properties for thermal sprayed NiCoCrAlY coatings2010In: Proceedings of the Thermal Spray: Global Solutions for Future Application (ITSC 2010) Conference: Singapore, May 3-5, 2010, 2010, p. 431-435Conference paper (Refereed)
  • 20.
    Hagqvist, Petter
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Emissivity estimation for high temperature radiation pyrometry on Ti–6Al–4V2013In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 46, no 2, p. 871-880Article in journal (Refereed)
    Abstract [en]

    The paper demonstrates a versatile procedure suitable for industrial implementation of temperature measurement on a hot titanium alloy. The driving force has been the need for an accurate temperature measurement during additive manufacturing using laser welding technology where Ti–6Al–4V-wire is melted. The challenges consider both industrial constraints and the varying emissivity of the surface. Measurements makes use of a narrow bandwidth spot radiation pyrometer and a calibration procedure for estimation of the surface temperature through spectral emissivity estimation. The theoretical results are validated through experiments. A number of difficulties in radiation temperature measurements for metals with varying surface properties are discussed; especially the case of surface oxidation. The uncertainty in temperature reading due to the uncertainty in the emissivity estimate is established along with a model that qualitatively describes surface oxidation. The procedure is expected to be useful for several manufacturing applications where it is important to control high temperatures.

  • 21.
    Hatefipour, Saeid
    et al.
    University West, Department of Engineering Science, Division of Automation Systems. saeid@termisk.se.
    Ahlberg, Jörgen
    Linköping University.
    Wren, Joakim
    University West, Department of Engineering Science, Division of Automation Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Thermal non-destructive testing: modeling, simulation and experiments for improved localization of hidden defects2014In: The 12th International Conference on Quantitative Infrared Thermography, 2014, p. 1-8Conference paper (Refereed)
    Abstract [en]

    During the last decades, a substantial amount of research and practical work has been conducted on non-destructive testing of materials using thermography. The performed studies elucidate the potential of various types of thermal non-destructive testing (TNDT) for different materials and applications, including various types of defects. This paper presents a method for detecting in-depth defects in metallic materials and a simulation model for the heat transfer in the material. Experiments are performed on a test specimen with artificial defects (flat-bottom holes). The detection method exploits spatiotemporal analysis in order to find deviations from a model of normality, and shows novel results. Thermal modelling is performed in order to have a base-line simulation model enable us to (a) investigate affecting parameters without repeating the experiments and (b) generalize the results and extend their validity to other cases. Results show that there is an acceptable compliance between simulated and measured thermal data. 

  • 22.
    Jalo Olsson, Sara
    et al.
    University West, Department of Engineering Science.
    Wulkan, Martin
    University West, Department of Engineering Science.
    Förbättringsförslag till avemballeringsfixtur och materialhantering2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport behandlar förbättringsförslag samt åtgärdsförslag för en avemballeringsfixtur och materialhantering. Avemballeringsfixturen används för att separera ett plåtparti från pall när plåtpartiet ska lastas in till Swegons automatlager. Vid projektets start framkom det att avemballeringsfixturen inte hade genomgått en riskanalys. Detta medför en ökad risk för olycksfall då operatörerna utför sitt arbete. Det framgick även att det inte fanns några arbetsinstruktioner tillgängliga för operatörerna. Saknaden av arbetsinstruktioner gör att operatörerna inte utför arbetsmomenten på ett optimalt sätt.

    Målet med projektet var att lokalisera riskerna med avemballeringsfixturen och materialhanteringen och ge förslag på åtgärder som minimerar/eliminerar dessa. Detta gjordes genom att ta fram lösningar för ombyggnation av befintlig avemballeringsfixtur och att presentera lösningar för en säkrare materialhantering.

    Efter genomförd feleffektsanalys och arbetsmiljöanalys togs ett flertal åtgärdsförslag fram. Huvudområdena som åtgärdsförslagen berör är fixturens konstruktion, avemballeringsfixturens helhet samt operatörernas arbetsområde. De olika åtgärderna inom respektive huvudområde fokuserades på att öka operatörernas och medarbetarnas säkerhet samt att åtgärdsförslagen ska göra operatörernas arbetsmoment lättare och smidigare. Åtgärdsförslagen har i denna rapport diskuterats för att förutsäga vilken effekt de kommer att ge i form av en säkrare arbetsmiljö för operatörerna och medarbetarna.

  • 23.
    Jiang, Janna
    University West, Department of Engineering Science, Division of Production Engineering.
    Modelling of mechanical properties of MAX-phase materials2009Licentiate thesis, comprehensive summary (Other academic)
  • 24.
    Lennartson, Bengt
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Sampled-data Hcontrol applied to the choice of controller order and sampling rate2010Manuscript (preprint) (Other academic)
  • 25.
    Markocsan, Nicolaie
    University West, Department of Engineering Science.
    Recent developments in coatings for gas turbines - TBC´s and other advanced coatings.2009In: Advanced in Surface Engineering Seminar: University of Techology, Tampere Finland, 19-23 Oktober, 2009Conference paper (Other academic)
  • 26.
    Markocsan, Nicolaie
    et al.
    University West, Department of Engineering Science, Division of Process and Product Development.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Vuoristo, Petri
    Overview of thermal spray activity in the European Nordic countries2010In: Proceedings of the 4th International Conference – Innovative technologies for joining advanced materials, ISSN 1844-4938, p. 109-115Article, review/survey (Refereed)
  • 27.
    Mossudd, Frida
    University West, Department of Engineering Science.
    Potential improvements for launches at Autoliv Sweden AB, focusing on the purchasing process2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During the summer 2012 a bachelor’s thesis was performed at Autoliv Sweden AB inVårgårda regarding potential improvements on launches, with focus on the purchasingprocess. The activities that were needed to be able to reach the main goal, proposals ofpotential improvements, were divided into three interim goals. The interim goals can beseen as activities along the way containing necessary information that was needed to beable to come up with potential improvements.

    The approach for the thesis was to first do a literature review on value stream mapping, how development projects at Autoliv Sweden AB are performed and on launches in theautomotive industry based on scientific articles. After the literature review a case study wasmade, using value stream mapping as a tool, on one development project at AutolivSweden AB for investigation of the launch. The result of the case study was presented intwo maps over the administrative stream for the components in the development project;one according to project time plan and one according to how the activities in the launchactual were performed.

    Based on the literature and the maps from the case study, three potential improvements, that would be relatively easy and inexpensive to implement, were found; (1) Involve thesupplier more and at an earlier stage in the development project, (2) involve the Logisticsdepartment more and (3) implement control level definition on the development projectsas well, not just the parts.

    The conclusion for this thesis was that if Autoliv Sweden AB decides to implement allproposed improvements both money and time will be saved.

  • 28.
    Nilsson, Jim
    et al.
    University West, Department of Engineering Science.
    Ericsson, Mikael
    University West, Department of Engineering Science.
    Danielsson, Fredrik
    University West, Department of Engineering Science.
    Virtual Machine Vision in Computer Aided Robotics2009In: Emerging Technologies & Factory Automation, 2009, p. 1-8Conference paper (Refereed)
    Abstract [en]

    In this paper a concept for Virtual Machine Vision is proposed using a commercial Computer Aided Robotics software called RobCad. The system utilizes ideal virtual cameras and lights for the simulation of a real vision system. Sensory data is sent to a vision software for data analysis. The Virtual Machine Vision together with the simulation model can be used to offline programming of a vision system. Experiments have been performed by capturing images of a test piece both in the virtual environment and in a physical experimental rig. To evaluate the concept, image analysis has been performed on these images using the same vision software. The results from the vision analysis of both the virtual and the real images are compared and show good agreement. The proposed system seems to be very promising and further development is ongoing.

  • 29.
    Pejryd, Lars
    et al.
    University West, Department of Engineering Science.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering.
    Isaksson, Marina
    CAPE.
    Machining aerospace materials with room-temperature and cooled minimal-quantity cutting fluids2011In: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, ISSN 0954-4054, E-ISSN 2041-2975, Vol. 225, no 1, p. 74-86Article in journal (Refereed)
  • 30.
    Ryberg, Anders
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Camera Modelling and Calibration with Machine Vision Applications2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Camera modelling and calibration are important parts of machine vision. They can be used for calculating geometric information from images. A camera model is a mathematical projection between a 3D object space and a 2D image. The camera calibration is a mathematical procedure calculating parameters of the camera model, usually based on several images of reference points. These fundamental parts of machine vision are improved in this thesis. One large part is the development of a generic camera model, GCM, that is accurate, computationally efficient and can be used for both conventional, fisheye and even catadioptric cameras. Different models were used in the past for conventional and  omnidirectional cameras and this is a well-known problem, the solution of which is described in this thesis. The accuracy of camera models is improved by introducing new ways of compensating for different distortions, such as radial istortion, varying entrance pupil point and decentring distortion. Calibration is mproved by introducing newmeans of calculating start estimates of camera parameters, from analysing shapes, sizes and positions of the reference points in the images. These start estimates are needed in order to make the calibration converge. Methods for calculating better reference centre points than the centres of gravity are developed in order to increase the accuracy further. Non-trivial null spaces that occur during calibration are identified. Awareness of these improve the calibration. Calibrations with different camera models are implemented and tested for real cameras in order to compare their accuracy. Certain models are better for certain situations, but the overall performance and properties are favourable for the GCM. A stereo vision welding robot system is developed, using the new model. It determines the geometry of a 3D weld joint, so that a robot can follow it. The same system is implemented in a virtual environment using a simulation software. Such simulation is important since it makes it possible to develop robot vision systems off-line.

  • 31.
    Ryberg, Anders
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Production Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Production Engineering.
    Eriksson, Kenneth
    University West, Department of Engineering Science, Division of Land Surveying and Mathematics.
    Nilsson, Jim
    University West, Department of Engineering Science.
    Larsson, Matthias
    University West, Department of Engineering Science.
    Stereo vision for path correction in off-line programmed robot welding2010In: Proceedings of the IEEE International Conference on Industrial Technology, 2010, p. 1700-1705Conference paper (Refereed)
    Abstract [en]

    The paper describes a versatile machine vision system for correcting off-line programmed nominal robot trajectories for advanced welding. Weld trajectory corrections are needed due to slight variations in weld joints. Such variations occur naturally because of varying tolerances in parts and to heat induced deformations during earlier weld sequences. The developed system uses one camera and a weld tool mounted on the robot hand. As a first step, the whole system, including the camera, is calibrated. Then the system takes images of the weld joint from different positions and orientations, and determines the weld joint geometry in 3D using a stereo vision algorithm and a novel camera model. The weld trajectory is then updated in the robot control system, and weld operation is performed. These steps are repeated for all weld sequences of the work piece. The strategy has successfully been demonstrated for a standard industrial welding robot and a standard FireWire CMOS camera. The maximum deviation of the trajectory found by the system compared to a reference (coordinate measuring machine) is 0.7 mm and the mean deviation is 0.23 mm. Thus, the system shows high potential for industrial implementation. ©2010 IEEE.

  • 32.
    Sigvant, Mats
    et al.
    Volvo Cars.
    Mattiasson, Kjell
    Chalmers Tekniska Högskola.
    Larsson, Mats
    University West, Department of Engineering Science, Division of Production Engineering.
    Determination of the formability of DP-steels by a combination of experimental methods and FE-simulations2010In: International Conference of International Deep-Drawing Research Group : IDDRG 2010: Austria, Graz, 31May - 2 June, Graz: Verlag der Technischen Universitat Graz , 2010, p. 195-204Conference paper (Other academic)
  • 33.
    Tano, Ingrid
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Nylen, Per
    University West, Department of Engineering Science.
    Wigren, Jan
    Gupta, Mohit Kumar
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Relationships between Coating Microstructure and Thermal Conductivity in Thermal Barrier Coatings – A modelling Approach2010In: International Thermal Spray Conference and Exposition, ITCS Singapore 2010: 3-5 May 2010,  Singapore, Düsseldorft: DVS Media , 2010, p. 66-72Conference paper (Refereed)
    Abstract [en]

    Fundamental understanding of relationships between coating microstructure and thermal conductivity is important to be able to understand the influence of coating defects, such as delaminations and pores, on heat insulation in thermal barrier coatings. Object-Oriented Finite element analysis (OOF) has recently been shown as an effective tool for evaluating thermo-mechanical material behaviour, because of this method's capability to incorporate the inherent material microstructure as an input to the model. In this work, this method was combined with multi-variate statistical modelling. The statistical model was used for screening and tentative relationship building and the finite element model was thereafter used for verification of the statistical modelling results. Characterisation of the coatings included microstructure, porosity and crack content and thermal conductivity measurements. A range of coating architectures was investigated including High purity Yttria stabilised Zirconia, Dysprosia stabilised Zirconia and Dysprosia stabilised Zirconia with porosity former. Evaluation of the thermal conductivity was conducted using the Laser Flash Technique. The microstructures were examined both on as-sprayed samples as well as on heat treated samples. The feasibility of the combined two modelling approaches, including their capability to establish relationships between coating microstructure and thermal conductivity, is discussed.

  • 34.
    Valiente Bermejo, María Asunción
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Guia de les escultures de Mollet del Vallès: Metalls, tècniques i curiositats2015 (ed. 1)Book (Other (popular science, discussion, etc.))
    Abstract [en]

    This publication presents a comprehensive study on the current 35 metal artwork pieces located in public spaces of Mollet del Vallès. The sculptures are described from a technical perspective: metallic alloys, joining techniques and protective mechanisms against corrosion are described. However, this research also reveals interesting curiosities and secrets hidden by these sculptures. The information is organised in clear datasheets, where the technical details from the experimental observation and from the official technical project reports are summarised. The symbolisms, anecdotes and curiosities included in this work were gathered during fruitful conversations with authors, authorities and companies involved in the execution of the metal works. The main aim of this work is to invite the reader to stroll into town, to rediscover our heritage, to appreciate it and to make new generations love it. 

1 - 34 of 34
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