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  • 151.
    Choquet, Isabelle
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Degond, Pierre
    Universit´e Paul Sabatier, Mathématiques pour l’Industrie et la Physique.
    Lucquin-Desreux, Brigitte
    Universit´e Pierre et Marie Curie-Paris 6, Laboratoire Jacques-Louis Lions.
    A hierarchy of diffusion models for partially ionized plasmas2007In: Discrete and continuous dynamical systems. Series B, ISSN 1531-3492, E-ISSN 1553-524X, Vol. 8, no 2, p. 735-772Article in journal (Refereed)
    Abstract [en]

    Partially ionized plasmas corresponding to different ionization degrees are derived and connected one with each other by the diffusion approximation methodology. These plasmas are the following electrical discharges:a thermal arc discharge, glow discharges in local thermodynamic equilibrium -LTE- and in non-LTE, and a non-LTE glow discharge interacting with an electron beam (or flow)

  • 152.
    Choquet, Isabelle
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Degond, Pierre
    Universit´e Paul Sabatier, Mathématiques pour l’Industrie et la Physique.
    Lucquin-Desreux, Brigitte
    Universit´e Pierre et Marie Curie-Paris 6, Laboratoire Jacques-Louis Lions.
    A strong ionization model in plasma physics2009In: Mathematical and Computer Modelling, Vol. 49, no 1-2, p. 88-113Article in journal (Refereed)
  • 153.
    Choquet, Isabelle
    et al.
    University West, Department of Engineering Science.
    Lucquin-Desreux, Brigitte
    University Pierre and Marie Curie, Paris, France.
    Non equilibrium ionization in magnetized two-temperature thermal plasma2011In: Kinetic and Related Models, ISSN 1937-5093, E-ISSN 1937-5077, ISSN 1, Vol. 4, no 3, p. 669-700Article in journal (Refereed)
    Abstract [en]

    A thermal plasma is studied accounting for both impact ionization, and an electromagnetic field. This plasma problem is modeled based on a system of Boltzmann type transport equations. Electron-neutral collisions are assumed to be much more frequently elastic than inelastic, to complete previous investigations of thermal plasma . A viscous hydrodynamic/diffusion limit is derived in two stagesdoing an Hilbert expansion and using the  Chapman-Enskog method. The resultant viscous fluid model is characterized by two temperatures, and non equilibrium ionization. Its diffusion coefficients depend on the magnetic field, and can be computed explicitely.

  • 154.
    Chourushi, T.
    et al.
    School of Mechanical and Aerospace Engineering and ACTRC, Gyeongsang National University, Jinju, Gyeongnam (KOR).
    Rahimi, Amin
    University West, Department of Engineering Science, Division of Welding Technology.
    Singh, S.
    School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link (SGP).
    Ejtehadi, O.
    Supercomputing Modeling and Simulation Center, Korea Institute of Science and Technology Information (KISTI), Daejeon (KOR).
    Mankodi, T. K.
    Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam (IND).
    Myong, R. S.
    School of Mechanical and Aerospace Engineering and ACTRC, Gyeongsang National University, Jinju, Gyeongnam (KOR).
    Thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow based on second-order non-Navierâ-Fourier constitutive model2022In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 187Article in journal (Refereed)
    Abstract [en]

    The thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow are investigated using first- and second-order Boltzmann-Curtiss-based constitutive models. The mixed modal discontinuous Galerkin scheme is used for solving the conservation laws in conjunction with the Maxwell velocity-slip and Smoluchowski temperature-jump boundary conditions. Also derived are new analytic solutions for compressible cylindrical Couette gas flow including the temperature profile, and they are used to verify the numerical scheme. Further, the second-order non-Navier-Fourier constitutive relations are derived for the cylindrical coordinates. Various abnormal behaviour is found in the second-order constitutive model, such as non-zero normal stress and excess normal stress, non-zero tangential heat flux, and flattened pressure and density profiles. The physical mechanisms behind this abnormal behaviour are found to be similar to the Knudsen layer in planar Couette gas flow, and the curvature of the cylindrical geometry does not affect the fundamental second-order physics. Moreover, two new abnormal mechanisms are found in diatomic and polyatomic gases: (i) the subtle interplay of excess normal stress (and bulk viscosity) with the nonlinear coupled constitutive relation, and (ii) the combined role of the bulk viscosity ratio and the specific heat ratio.

  • 155.
    Christensen, Tommy
    University West, Department of Engineering Science, Division of Production Engineering.
    Lean Automation på Saab Automobile AB: ett hållbart och flexibelt produktionskoncept2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A new concept of production – Lean Automation – is being developed and implemented at Saab Automobile AB. The aim is to develop solutions for automation that supports the Lean Production principals and way of work.

    A basic idea is that automation should be build from simple, standardized and modular equipment and that it can be reconfigured by in house personnel.

    During 2010, two pilots have been installed: Transport using a simple AGV (Lean AGV) and Lean Automation Robot Cell (LARC). Those components are parts of this study that is aiming for a production system with an unchanged high level of productivity also during periods of frequent changes in volume and product scope.

    The study underlines the importance of gathering the production personnel to enable work balancing, but also to achieve a visual process where errors urgently can be discovered and resolved. The robots work balancing requires a somewhat different approach focusing on the distribution of work elements and taking advantage of the equalizing effect in a common production flow.

    A tool for an expedient balancing of value added work is introduced. The tool is intended for the balancing of both manual and robotized work.

    Further, a method to connect the sub assembly level to the main flow is presented. Fork lift trucks and manually loaded feeders is replaced by a simple flow of AGV’s. The system is conveying information about the state of production through the presence of empty carriers. Through this visual system, plus the use of the team concept to achieve a cheap and efficient buffer, shortage of material is prevented.

    For the selection of internal material flow systems, a set of general guidelines is proposed and exemplified. Finally, the adoption of different solutions for flexibility is linked to the level of assembly and this is also linked to the aspects of parallel versus serial production flow.

    Download full text (pdf)
    LeanAuto_Saab-HV_2011
  • 156.
    Cirkic, Aldin
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Qaljaee, Ali
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Utveckling av motoriserad vertikal linjärenhet för kontinuerlig drift2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis work has been carried out with the purpose of developing and defining a motorized vertical linear actuator for continuous operation. In the present situation, the company does not haves a linear actuator that is capable of 1600 millimeters stroke with a load of 100 kilograms. The goal of the thesis is to present a final conceptual solution through a product development process. Software programming or electronics development is available within the company to define the function, which has been considered as a demarcation.

    The project's method is a general product development process. The first step was to establish a project plan. By identifying the client's requirements the specification could be developed which has transferred into a QFD. The next step was to develop different solutions using external and internal search methods and choose a final concept. To ensure that the final concept is safe, two different risk analyzes have been created. The concept was demonstrated in a CAD software and then different calculations and FEM analyzes were performed. The final conceptual solution turned out to be a motorized linear actuator. To make the load weightless, a pneumatic cylinder has been introduced into the system. The positioning of the weight is carried by a ball screw which is driven by a belt and a stepper motor.

    The result of calculations and analyzes of machine elements showed that the device has a theoretical service life of at least 10,000 hours. The developed conceptual solution meets the goal of establishing a final concept for a linear actuator that can handle a stroke of 1600 millimeters with a load of 100 kilograms.

  • 157.
    Ciudad de Lara, Irene
    University West, Department of Engineering Science.
    Investigating the Microstructure and Tribological Performance of HVAF sprayed Ti-6Al-4V  coatings2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ti-6Al-4V is one of the most widely used titanium alloys nowadays and has mechanical properties and corrosion resistance superior to that of steel and aluminum alloys. Hence, new technologies have been developed due to the fact that titanium components make excellent candidates for manufacturing from powder as new repair technologies, such as thermal spray techniques.

    One of these technologies would be High Velocity Air Fuel (HVAF) thermal spray method, consisting on using a mixture of combustible and compressed air for accelerating the powder stream trough a nozzle, where little research has been done on Ti-6Al-4V coatings. Therefore, in this project, High Velocity Air Fuel sprayed coatings of Ti-6Al-4V will be studied regarding its tribological properties, mechanical properties such as hardness, microstructure analysis before and after applying different heat treatments, and finally erosion performance. All of the results will be contrasted with Ti-6Al-4V substrate and also with research from the literature in order to get a better understanding of its performance.

    This thesis aims to expand the study of High Velocity Air Fuel Ti-6Al-4V coatings and to set a starting point for further studies in the repairing of this alloy by coating technology.

  • 158.
    Clement, C.
    et al.
    National School of Engineers, University of Limoges, Limoges, 87280, France.
    Sadeghimeresht, Esmaeil
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Lyphout, Christophe
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Corrosion behavior of HVAF- and HVOF-sprayed high-chromium Fe-based coatings2015Conference paper (Refereed)
    Abstract [en]

    Fe-based coatings with three particular elemental compositions and two different powder particle size were prepared by high-velocity air fuel (HVAF) and high-velocity oxy fuel (HVOF) techniques. The corrosion behavior of which were comparatively studied in 3.5 wt.% NaCl solution. The results indicated that the coatings produced by HVAF process exhibited denser structure with lower porosity. Polarization and electrochemical impedance spectroscopy (EIS) tests indicated that the HVAF coatings provided better corrosion resistance than the HVOF coatings. The presence of defects was significant in HVOF coatings. The investigation illustrated that the corrosion paths initiated and grow through defects of the coating. Furthermore, adding Cr strongly improved the corrosion resistance of the coatings. The results confirmed that the cheap HVAF process could be a potential alternative to HVOF to fabricate Fe-based coatings for industrial applications.

  • 159.
    Clovis, Killian
    University West, Department of Engineering Science.
    Deposition and characteristics of thermal sprayed layers as solid-state thin film battery components2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the depletion of fossil fuel energy sources, air pollution and carbon emissions becoming more problematic, a transition to renewable energies is required. The most common renewable energy storage nowadays is lithium-ion batteries. However, those batteries cannot meet the requirement for the increasing demand in batteries of the growing market. Moreover, producing higher density batteries at a lower cost present safety issue due to the liquid electrolyte present in lithium-ion batteries.

    All Solid-State Batteries were investigated to meet the market requirements, and to solve the safety issues presented by using liquid electrolytes. Solid State Thin-Film Batteries are promising power sources for micro devices due to their high safety, high energy density and easy integration with semiconductor processes. However, the conventional manufacturing methods of those thin films are vacuum-based and have a high cost and a low deposition efficiency which prevent the large-scale manufacturing of thin films as battery materials. Suspension Plasma Spraying and Atmospheric Plasma Spraying are two promising processes to manufacture thin film as battery components due to the versatility of materials for the substrate and their economic deposition process.

    Therefore, the aim of this study is to investigate the possibility of utilizing thermal spray (TS) approaches to manufacture thin film battery components with desired characteristics as well as to explore the possibility of manufacturing multi-layer coatings to fabricate a complete Solid-State Thin Film Battery cell. The other aims of this study are to investigate the influence of spraying distance on the thin films manufactured with Suspension Plasma Spraying and Atmospheric Plasma Spraying and to analyse the influence of additives on suspension preparation.

    During this thesis, porosity measurements, surface roughness measurement, elemental analysis, thickness measurement, deposition efficiency measurements, surface morphology analysis and cross section microstructure analysis have been performed. Three materials wereinvestigated LTO as an anode material, LLZO as an electrolyte material and NMC as a cathode material. Results showed that depending on the material, spraying distance can have an influence on the phase composition, the surface roughness, the elemental distribution, and the surface morphology of the samples.

    The conclusion of this thesis is that Suspension Plasma Spraying and Atmospheric Plasma Spraying can manufacture double-layer (LTO/LLZO) coatings and triple-layer (LTO/LLZO/NMC) coatings. However further investigations are required regarding plasma spraying of thin film as battery components to achieve desired characteristics. 

  • 160.
    Coll Ferrari, Maria Teresa
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Forsberg, Amanda
    Uddeholms AB.
    Andersson, Jörgen
    The Swedish School of Mining and Metallurgy.
    Mikula, Pavol
    Nuclear Physics Institute ASCR.
    Beran, Premysl
    Nuclear Physics Institute ASCR.
    Effect of Austenitising Temperature and Cooling Rate on Microstructure in a Hot-Work Tool Steel2014In: Proceedings of the 6th International Swedish Production Symposium / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    The effects on microstructucture of austenitising temperature and cooling rate during hardening were studied for a hot-work tool steel. Transformation temperatures were determined by dilatometry, scanning electron microscopy was used to characterise the microstructure and both retained austenite contents and their lattice parameters were measured by neutron diffraction. For lower cooling rates, lower austenitising temperatures produce larger amounts of both retained austenite and bainite. Retained austenite in bainitic structures is higher in carbon than in martensitic structures. Consequently, lowering the austenitising temperature will affect microstructure and properties.

  • 161.
    Dahat, Shubham
    University West, Department of Engineering Science, Division of Welding Technology.
    A methodology to parametrize Wire + Arc additive manufacturing applied to a high strength low alloy steel2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wire + Arc Additive Manufacturing (WAAM) is a potential high deposition rate process that can be efficaciously used to manufacture and repair functional components. To manufacture functional components out of WAAM, the first requirement is to reach near net geometrical and shape of the build, considering the costs to redress the built part. The functionality of the builds (mechanical properties and occasionally wear/corrosion resistance) complements the requirements. As-built parts produced by WAAM have inherent lateral surface waviness (undulated surface) and may deviate from the target dimension, post processing is often required to eliminate lateral surface waviness and oversizing, i.e., to remove the extra material in such a way that all the surfaces turn evenly flat and match the design dimensions. Post-working costs must be mitigated to make WAAM manufacturing competitive with other subtractive or forming methods. The amount of this extra material which leads to lateral surface waviness varies with parametric set and can be reduced by selecting parametric set which produce minimum residual material. Therefore, somehow different from welding operations, WAAM parametrization is critical for the shape and dimensional tolerances. Parametrization of WAAM is a difficult task, because multiple parameters are involved and parameters are inter-dependent on each other, making overall process complex. In addition, a set parameterization that attends geometric aspects may not fulfill the functionality requirements. An approach to study WAAM would be through operational maps which can be used to select parametric set for a given target dimension and functional properties. Upon parametrization, operational map will indicate the workable parametric set for a range of LW and which is called as working envelope.

    The objective of this work was the development of a methodology to parametrize WAAM, aiming dimension repeatability, tolerances and mechanical performance of the build, such that desirable quality and cost can be achieved. Desired quality here means presence of no imperfections and discontinuities that impairs functionality. The consumables were chosen to match benchmarked mechanical properties of high strength low alloy steels, using as novity in WAAM a metal-cored wire as feedstock.

    The work development had 4 stages. As a starting point, the stage named "Mock Design" had the objective of finding, without experimentation, a rough operational map to visualize the expected operational map and further reduce the number of experiments. The layer dimension was estimated from deposition rates of the consumable datasheet and assuming semi-circular cross-section of the deposited layers.

    At the second stage, "Pre-requisite for realistic operational map", the objective was to determine the actual melting rate and the workable limits of I and TS with the chosen consumable and equipment. This approach resulted in a 2nd approximation operational map with a working envelope, yet roughly estimating the layer cross-sections.

    Within the "Realistic operational map" stage, a design of experiment was applied to cover the working envelope already defined in the previous stage and long and tall walls were additively manufactured. Actual values of LW (external and effective) measured, geometrical parameters (waviness and buy-to-apply indexes) were calculated and a realistic operating envelope was reached. Justifications for the behaviour of the metal deposition at different areas of the operating envelope were devised.

    The operational envelope was further validated (4th stage) by selecting a target LW and finding corresponding three parametric set (covering the whole range of operational map) to produce walls on which geometry, mechanical characterisation and production time study was acceptable. Tensile tests were carried out in longitudinal and transverse direction. Hardness profile on the cross section from the bottom to top were raised.

    Finally, a brief simulation of deposition time was developed to demonstrate the weight of the TS on the final deposition time and wall quality, as a function of a target wall width. The geometrical characterisation showed high precision in achieving target dimension. For a target LW, it was also found that there were no imperfections or discontinuities present in the walls built according to X-ray radiography and bend test. However, some drop of mechanical properties and anisotropy were observed when the TS was higher, although matching in general the benchmark.

    As a conclusion, this approach (operational map) helped in determining the combination of I and TS which leads to either higher robustness, fast production, better mechanical properties or less material to be removed in post processing for a target LW, facilitating the decision making.

  • 162.
    Dahlberg, Simon
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Implementering av förebyggande underhåll som en del av ISO-certifieringar2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To become more competitive on the market Stålprofil AB has decided to obtain ISO 9001, 14001 and the upcoming 45001. As a part of this work, Stålprofil would like to implement preventive maintenance on four of the companies machines. This thesis has developed a proposal on preventive maintenance and how the company should implement it. Further an analysis of the company's current maintenance work and a study of the correlation between the three standards and preventive maintenance is carried out.

    A literature study was carried out to gathered information about maintenance. Based on this literature study and the small amount off documentation available at the company a proposal for preventive maintenance was carried out.

    In order to analyze and describe the company´s current maintenance work two observations were carried out. One observations were performed on a scheduled maintenance work and one a corrective maintenance. In addition to this reliability measurement on the four machines was carried out. The measurements should be considered whit great cautions as it only was performed during 900 minutes.

    The conclusions drawn are that the company wasting time by the staff is busy with other tasks and that the maintenance work that was observed was carried out in an unplanned way, even if they were planned.

  • 163.
    Dahlin, Jonathan
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Widström, Maria
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Utveckling av hydrauliskt lås till lastväxlare2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The bachelor’s thesis was carried out in collaboration with the design department at JOAB in Dals-Rostock. JOAB develops, manufactures, and assembles accessories for trucks with a focus on the European market. Hooklifts are a product that the company manufactures and are used to shift loads that are collected in different types of load carriers. The load carriers are usually containers, silos, or flatbeds of various kinds. Hooklifts are equipped with a hydraulic lock, which secures the load carrier from falling out of position after it has been lifted onto the truck.At present, compatibility problems arise between different load carriers, and the hydraulic lock on the company's hooklift model Hookmaster. To increase compatibility, JOAB therefore wants to develop the hydraulic lock on the Hookmaster model. The work began by reviewing previous development work, standards, and current constructions. To identify the main problem, cases were investigated where compatibility problems had arisen and what caused this. The work was limited to the components of the hydraulic lock, as well as its adjacent components. To solve the problem, a well-defined product development process with structured methods was used. Several concepts were generated using brainstorming methods performed together with JOAB. The final concept selection was performed through the application of concept selection matrices. The work resulted in CAD-models with associated manufacturing drawings of a hydraulic lock that was attached to the hooklift frame in the same way as JOAB's previous hydraulic locks. The work is considered successful as the goal have been achieved and customer requirements have been satisfied. The report concludes with recommendations for continued work, on the points that have fallen outside the boundaries of the work. 

  • 164.
    Dahlqvist, Filip
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Svantesson, Joel
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Konceptframställning av utrustning för medicindistribution på sjukhusavdelning för slutenvård2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today's stressful working environment makes high demands of the personnel in the health care sector worldwide. A literature study has thus been performed to be able to establish how nurses experience stress and other sources of psychosocial illnesses as well as to point out what the main sources of primarily stress are. This information is then used to analyze if the automation of medicine distribution could help in the fight against psychosocial illnesses including stress.

    A status analysis is performed at a ward on Uddevalla hospital, after establishing that the automation can help, to learn how they solve their tasks today, if there is something special the project group needs to think about at the development of an automatic solution and what preferences they have on an automatic solution.

    A concept development is performed with information from the status analysis up until a concept has been chosen.

    When a concept has been chosen, an analysis is performed on products that resemble the concept. With this analysis the final target specifications to the product characteristics from the concept development are chosen.

    The results from the aforementioned methods gave the conclusions that an AGV solution that is loaded by a robotic arm, transports the medicine in locked boxes and unloads the medicine by reading a code or a tag was the best concept according to the chosen selection criteria.

    The chosen concept contributes to a reduction in the lack of time buy being, at least, 143% faster than for the nurses to get the medicine on their own.

    The final target specifications are presented in a QFD to get an overview on what the most important product characteristics are.

    Because of the human factor in the distribution of points uncertainties in the selection matrices can exist, even though the members of the project group have tried to be as objective as possible.

  • 165.
    Dahlén, Erik
    et al.
    University West, Department of Engineering Science.
    Haglund, Fredrik
    University West, Department of Engineering Science.
    FBM Featured Based Machining 20232023Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Feature-Based Machining, FBM is an engineering tool that aims to expedite and optimize machining processes for CAM machinists while ensuring standardization throughout. The purpose of this study was to examine the maturity of FBM as a tool for companies like GKN and determine its readiness for large-scale implementation. Additionally, the investigation aimed to assess the software’s effectiveness across various types of geometries and whether it could meet the required performance criteria.This study aimed to explore the potential of Feature-Based Machining and assess its suitability within GKN's operational framework. A primary focus was to evaluate the readiness of FBM for widespread adoption and its compatibility with various intricate details. By delving into these aspects, the study aimed to determine the applicability and viability of FBM within GKN's operational context. Ultimately, the goal was to determine whether FBM could deliver the desired outcomes and function effectively within the specific manufacturing context of GKN.Through thorough analysis and tests, the study aimed to provide insights into the capabilities and limitations of FBM. By scrutinizing its performance, reliability, and adaptability, the research sought to ascertain the tool's feasibility as a reliable solution for enhancing machining efficiency. By addressing these critical questions, the study aimed to offer valuable recommendations regarding the potential implementation of FBM within GKN's operations and its broader adoption in the manufacturing industry.

  • 166.
    Dai, Kaixiang
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Battery cell thermal modelling and fault injection2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lithium-ion batteries are widely used in electrical vehicles due to their high energy density and high discharge current. During the charge and discharge phases, the internal resistance of batteries can generate great amounts of heat. Temperature is a very crucial factor that affects the battery life and safety. The lithiumion batteries’ heat generation and temperature distribution were studied to provide a good reference for designing cooling systems. Furthermore, extreme thermal abusive conditions such as internal short-circuit are also simulated in this project.

    This project was conducted at NEVS in collaboration with University West in Trollhättan. The heat generation of battery cells and fault injection were simulated based on experiments and CFD (computational fluid dynamic) method.

    A number of tasks had to be done in order to build the battery thermal model. The first issue that had to be resolved was being able to gain sufficient physical parameters of Lithiumion battery and this was accomplished through experiments. Once this had been achieved, the final step was to implement the constructed battery thermal model via CFD. The surface temperature of the battery cells was used to validate the simulation model. Three different discharge tests were performed in the experiment part, the discharge currents were 1C, 2C and 3C respectively. The simulated temperatures were compared with real battery temperatures and they were closely corresponding to each other in temperature. Fault injections of the battery were also simulated to have a view on the battery thermal behaviour under extreme abusive conditions. The battery internal shorting has been simulated with different internal resistance and different cross-section areas.

  • 167.
    Dalaei, K.
    et al.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology.
    Karlsson, B.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology.
    Svensson, L. E.
    University West, Department of Engineering Science, Division of Production Engineering.
    Stability of shot peening induced residual stresses and their influence on fatigue lifetime2011In: Materials science and engineering A, ISSN 0921-5093, Vol. 528, no 3, p. 1008-1015Article in journal (Refereed)
    Abstract [en]

    Mechanical surface treatment methods such as shot peening may improve the fatigue strength of materials. In this study, the effect of shot peening on strain controlled constant amplitude fatigue loading of a near pearlitic microalloyed steel was investigated. The stress amplitudes throughout the whole lifetime were followed, in addition to detailed recording of stress-strain hysteresis loops, particularly at small cycle numbers. The detailed relaxation of residual stresses and the changes in full width of half maximum (FWHM) of the X-ray peak at the surface and in depth as function of the number of cycles and plastic strain were recorded. By these techniques, the onset as well as the rate of relaxation of residual stresses could be followed at different strain amplitudes. Pronounced increase in lifetime of the shot peened specimens tested at total strain amplitude smaller than 0.3% (corresponding to 0.034% plastic strain amplitude) was achieved. This coincides with reasonably stable residual stresses at the surface and in depth. © 2010 Elsevier B.V.

  • 168.
    Dalung, Emma
    et al.
    University West, Department of Engineering Science.
    Johansson, Mikael
    University West, Department of Engineering Science.
    Kvalitetssäkring av monteringsmoment vid Fasta Motorers F11-montering utifrån en process-, felläges- och effektanalys2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis an investigation has been made in order to find possibilities to assure the quality at an assembly line at Parker Hannifin Manufacturing Sweden AB:s facility in Trollhättan. The purpose with the study was to improve the quality assurance at Fixed Motors F11-assembly line, where the work was based on an already conducted process-FMEA. In order to verify and further investigate the customer perspective, an inquiry was also done to see what customers complained about, this with help of PQP, Product Quality Problems, and NCMR, Nonconformance reports.

    By analyzing the process-FMEA, PQP and NCMR reports an identification and prioritization of critical failures were made. The result from these steps was three failures, incorrect positioning of the bearing house, picking of incorrect material and incorrect gear timing. These three were considered to be the most critical failures to quality assure.

    The aim with the quality work were set to reduce the total RPN, Risk Priority Number, of the process-FMEA, which was rendered by applying a concept generation and a concept selection for the specific failures.

    In relation with the concept selection, interviews were made with staff that was considered important and vital for the project. This was made to identify specific customer needs regarding solutions to the three failures. From these needs a target specification was developed to ease the generation of concepts. After generating a number of well specified concepts, a concept selection was made using the two methods screening and scoring and an additional Parker method called 3P to further establish that the right concepts was chosen. Further it was then possible to update the process-FMEA with the chosen concept solutions and by doing that reaching the project aim. By implementing the solutions it was possible to reduce total RPN, 6415, with 47,5 percent.

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    Kvalitetssäkring av monteringsmoment vid Fasta Motorers F11-montering utifrån en process-, felläges- och effektanalys
  • 169.
    Damgaard, Kajsa
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Söderling, Daniella
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Visuell förmedling av information: Hur en verksamhet kan förbättra och uppnå en effektiv och pedagogisk visualisering2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Flows of information and communication in an organization is significant, although the complexity and structure may vary. Trough visualization the transmission and clarification of information is facilitated. It is significant to mediate information, concerning the business performance indicators, pedagogical and efficiently to enhance the understanding and commitment in order to pursuit a company's vision. Purpose: Visualize determined performance indicators to mediate information efficiently and pedagogical. In order to fulfill the purpose, two questions have been formulated: - How can information be communicated visually in a pedagogical and efficient way? - How can the continuous work regarding follow-up and visualization improve? Method: A case study have been performed at Preem AB in Lysekil, and five companies have been used in order to perform benchmarking with the purpose of collecting empirical data for the study. Furthermore, the theoretical data have been collected by a conducted litterateur study based on relevant books, articles and previously written student thesis. Both empirical and theoretical data has been compiled and analyzed. Conclusions and recommendations: Based on conducted interviews and the analysis, conclusions and recommendations have been obtained which are intended for the case company. The recommendations may be generalized given that the existing needs and conditions at a different company show a resemblance. Following recommendations have been made: - Introduce more figures, tables, charts and colors. - Introduce more standardized methods. - Complement work methods and tools with explanatory text and guidelines. - Break down and adapt information to respective level. - Work more with feedback. - Map the chain of how information and communication flows. - Allocate resources regarding time and peoplo for continuous improvement. .

  • 170.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    A flexible lean automation concept for robotized manufacturing industry2011In: Proceedings of the 4th International Swedish Production Symposium: 3 - 5, May, Lund, Lund: Swedish Production Academy , 2011, p. 361-367Conference paper (Refereed)
    Abstract [en]

    Due to constant changesin the market there is a need for low-cost and low-volume manufacturing.Usually this type of production is difficult to automate due to the time ittakes to become profitable and the inflexibility of such solutions.  Therefore, flexible automation solutions needto be addressed together with cost effective aspects. In this paper, a newconcept for the design of a flexible, robotized solution based on leanautomation is presented and simulated. The proposed lean automation concept isformed of standardized robot stations, human-robot collaboration and costeffective level of automation. The main goals are flexible automated productionsystem and reduced production cost. This paper shows that the proposed flexiblelean automation concept has some key advantages compared to the traditionalrobot cells; a longer lifetime for the robot cell as well as being easier tore-balance, introduce new parts to and expand the cell. Further, it also showsthat the proposed concept reduces the cost for automation of products with low volume.

  • 171.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Gustavsson, Steve
    University West.
    A Flexible Lean Automation Concept for Robotized Manufacturing Industry2010In: MESM 2010: 11th Middle Eastern Simulation Multiconference / [ed] Mar wan Al-Akai di, Ostend: Eurosis , 2010, p. 101-104Conference paper (Refereed)
    Abstract [en]

    This paper describes a general virtual manufacturing concept for industrial control systems. Our virtual manufacturing concept provides a distinct advantage; programming, verification and optimisation of complex real-time dependent control functions described by real control code, which can be directly transferred to the real manufacturing system. To achieve this distinct advantage, a time synchronised virtual manufacturing system is a necessity. The aim of this paper is thus to present and to describe in detail, our proposed virtual manufacturing concept. To the authors’ knowledge no such general virtual manufacturing concept, i.e. one that can correctly handle complex real-time dependent control functions, currently exists. To summarise previous work related to virtual manufacturing and industrial control systems, several critical issues have been identified. The virtual manufacturing concept proposed in this paper addresses these issues. To verify that our concept can manage these critical issues found and further is suitable in industrial applications a virtual manufacturing test case is also presented. The test case, that includes motion control (i.e. servo), complex control functions, real control systems etc., was carried out with success.

  • 172.
    Danielsson, Rebecka
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Kortläsare för återvinningscentral2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Avfallshanteringen Östra Skaraborg (Waste management Eastern Skaraborg) (AÖS) needs a new card reader for their recycling centers. This project will develop this with consideration to different forms of identification and user friendliness. The project is limited to reading the identification forms of passport, driver's license, European ID-card, national ID-card and ID-cards from banks. The information will be interpreted and translated before it is sent further to the database of AÖS, and after that ends the project's responsibility for the information. Product development methods like concept screening and concept scoring are used. Other tools include programming in C language in a programming environment, design of the box in a computer aided design program and a material selection from a material database.

    Information that steered concept generation and selection were for instance customer demands, climate data, technology in the realm of information reading and the layout of earlier mentioned identification forms.

    The chosen concept is a designed box containing a flatbed scanner (Canon CanoScan LiDE 220) that is connected to a computer (ASUS VivoPC VM42) that is powered on by the user with a start button. This computer is in turn connected to an I/O module (National Instruments USB-6002) that turns on lamps to inform the user if they need to rescan. The computer reads the characters on the ID-card and isolates the personal ID number before sending it in the form of three four digit 16 bits integers via network cable to the database that is localized in a raspberry pi server. The computer does this in its startup routine by first starting the program that scans and turns the scanned information into a pdf, then a translation program takes over that turns the information in the pdf into a string that another program processes to get the personal ID number. This program then sends a signal integer to the I/O-module, and the personal ID number (if found) via Modbus tcp to the database.

  • 173.
    Das, Kallol
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Effect of tool wear on surface integrity and burr formation in drilling of titanium alloy, Ti6Al4V2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Titanium alloys have been extensively used in aerospace industries and account for almost 30 wt% of materials used in an aerospace engine. Surface integrity of machined titanium components has a significant effect on reliability and sustainability those components in aer-ospace industry. Surface integrity could be affected by process parameters, cooling condi-tions and the wear level of the tools used in machining. An important example is the surface integrity of the holes drilled in titanium alloy Ti6Al4V. Although previous studies have shown that tool wear and cutting parameters influence surface integrity and burr formation, little work has been published about the effect of drill wear on the surface integrity and burr formation in drilling of titanium alloys in detail. In this study the influence of tool wear and use of coolant on surface integrity and burr formation in drilling of Ti6Al4V has been inves-tigated by metallographic study and micro hardness measurement of the material adjacent to holes drilled on plates of Ti6Al4V with drills of various wear levels and at three different cutting conditions. Micro structural and micro hardness alteration in drilled holes at the hole entrance, in the middle of the hole and at the hole exit as well as burr formation have been analyzed for the tool wear levels 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mm. The tests were carried out in vertical direction without coolant and horizontal and vertical directions with coolant. The results show that limiting the wear level on the drills and use of coolant significantly lower the burr formation and microstructural alterations. Higher tool wear levels increase the depth of micro structural deformation, micro hardness and burr heights. These differences are not significant for wear levels up to 0.4 mm irrespective of cutting conditions but increase sig-nificantly when tool wear level exceeds 0.6 mm.

  • 174.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Automation Systems.
    Feedback Control of Robotic Friction Stir Welding2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The Friction Stir Welding (FSW) process has been under constant developmentsince its invention, more than 20 years ago. Whereas most industrial applicationsuse a gantry machine to weld linear joints, there are applications which consistof complex three-dimensional joints, requiring more degrees of freedom fromthe machines. The use of industrial robots allows FSW of materials alongcomplex joint lines. There is however one major drawback when using robotsfor FSW: the robot compliance. This results in vibrations and insufficient pathaccuracy. For FSW, path accuracy is important as it can cause the welding toolto miss the joint line and thereby cause welding defects.The first part of this research is focused on understanding how welding forcesaffect the FSW robot accuracy. This was first studied by measuring pathdeviation post-welded and later by using a computer vision system and laserdistance sensor to measure deviations online. Based on that knowledge, a robotdeflection model has been developed. The model is able to estimate thedeviation of the tool from the programmed path during welding, based on thelocation and measured tool forces. This model can be used for online pathcompensation, improving path accuracy and reducing welding defects.A second challenge related to robotic FSW on complex geometries is thevariable heat dissipation in the workpiece, causing great variations in the weldingtemperature. Especially for force-controlled robots, this can lead to severewelding defects, fixture- and machine damage when the material overheats.First, a new temperature method was developed which measures thetemperature at the interface of the tool and the workpiece, based on the thermoelectriceffect. The temperature information is used as input to a closed-looptemperature controller. This modifies primarily the rotational speed of the tooland secondarily the axial force. The controller is able to maintain a stablewelding temperature and thereby improve the weld quality and allow joining ofgeometries which were impossible to weld without temperature control.Implementation of the deflection model and temperature controller are twoimportant additions to a FSW system, improving the process robustness,reducing the risk of welding defects and allowing FSW of parts with highlyvarying heat dissipation.

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    PhD Thesis - Feedback Control of Robotic Friction Stir Welding
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  • 175.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Deflection model for robotic friction stir welding2014In: Industrial robot, ISSN 0143-991X, E-ISSN 1758-5791, Vol. 41, no 4, p. 365-372Article in journal (Refereed)
    Abstract [en]

    Purpose - This paper aims to present a deflection model to improve positional accuracy of industrial robots. Earlier studies have demonstrated the lack of accuracy of heavy-duty robots when exposed to high external forces. One application where the robot is pushed to its limits in terms of forces is friction stir welding (FSW). This process requires the robot to deliver forces of several kilonewtons causing deflections in the robot joints. Especially for robots with serial kinematics, these deflections will result in significant tool deviations, leading to inferior weld quality. Design/methodology/approach - This paper presents a kinematic deflection model, assuming a rigid link and flexible joint serial kinematics robot. As robotic FSW is a process which involves high external loads and a constant welding speed of usually below 50 mm/s, many of the dynamic effects are negligible. The model uses force feedback from a force sensor, embedded on the robot, and predicts the tool deviation, based on the measured external forces. The deviation is fed back to the robot controller and used for online path compensation. Findings - The model is verified by subjecting an FSW tool to an external load and moving it along a path, with and without deviation compensation. The measured tool deviation with compensation was within the allowable tolerance for FSW. Practical implications - The model can be applied to other robots with a force sensor. Originality/value - The presented deflection model is based on force feedback and can predict and compensate tool deviations online.

  • 176.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Soron, Mikael
    ESAB Welding AB .
    Ilar, Torbjörn
    University West, Department of Engineering Science, Division of Production Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Process and Product Development.
    Friction stir welding with robot for light vehicle design2010In: Proceedings from the 8th International Friction Stir Welding Symposium: Timmendorfer Strand, Germany 18-20 May 2010, The Welding Institute , 2010Conference paper (Other academic)
    Abstract [en]

    Reducing weight is one of the enablers to design more environmentally friendly vehicles. Friction Stir Welding (FSW) supports low weight design through its capability to join different combinations of light weight materials, e.g. different aluminium alloys, but also through its possibilities in producing continuous joints. StiRoLight is a recently started project for robotised FSW for joining of light weight materials emphasising on the vehicle industry, an industry with a long-time experience of robotic welding. The first task involves investigation of force feedback for maintaining the desired contact force. Another important aspect in robotised FSW is the compliance of the robot, which may result in deviations from the pre-programmed path as a result of the high process forces experienced during the welding operation. The further exploration of three-dimensional FSW seams and definition of the process windows will be part of further research within this project.

  • 177.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Verheyden, Bert
    University West, Department of Engineering Science, Division of Production Engineering.
    Robotic Friction Stir Welding for Automotive and Aviation Applications2010Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Friction Stir Welding (FSW) is a new technology which joins materials by using frictional heat. Inthe first part of this thesis, a profound literature study is performed. The basic principles, therobotic implementation and possibilities to use FSW for high strength titanium alloys areexamined. In the next phase, a FSW-tool is modelled and implemented on an industrial robot in arobot simulation program. Reachability tests are carried out on car body parts and jet engineparts. By using a simulation program with embedded collision detection, all possible weldinglocations are determined on the provided parts. Adaptations like a longer FSW-tool and amodified design are suggested in order to get a better reachability. In different case studies, thenumber of required robots and the reduction of weight and time are investigated and comparedto the current spot welding process.

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  • 178.
    de Haan, Lennart
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Automated Defect Detection and Decision-support for internal hole inspection of critical aerospace parts: Feasibility study2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project was tasked with answering the question: “Can inner wall surfaces of a critical aerospace part be inspected by placing a camera on the outside and making use of an active positioning system, such that images can be acquired and defects can be detected on the image?” The reason why inspection is important is to ensure that the predetermined quality is achieved and no defects are present.

    The inspection system is set up by using a lens, camera, and robotic arm. Which was mounted to the side of the GKN inspection module, that is used to rotate the part. To ensure all wall surfaces are clearly visible and in focus, the lens must be centered infront of the hole. To accomplish this the camera is fixed on the robot which allows it to be positioned precisely. The camera was calibrated at a specific distance from the part. In the image, the distance between the center of the hole and the center of the image is measured. This measurement is sent to the robotic arm to move those distances and position the lens accurately in front of the hole. 

    Defect detection was performed by using the built-in surface defect-detection function in the Cognex software. A quantitative method was evaluated where the number of detected flaws returned by the software was used as a basis for determining the compliance of the hole. During the experimental phase, images were taken of 144 different holes present in the parts. The diameter and depth of each hole was around 5 and 10 mm respectively. All interior surfaces of holes were clearly visible and in focus. Then in 12 of the holes defects were introduced. These defects could be clearly seen in the images. However, the flaw detection algorithm was unable to correctly differentiate between the holes with defects and those without. This was due to the high level of noise present in the clean images. However, this visual inspection system allows for easier access to the tiny holes by displaying the image on a screen, greatly assisting the operator in determining if a defect is present in the hole or not

  • 179.
    Dedovic, Edina
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    AR-based Assistance in Woodworking Industry2021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Augmented Reality head-worn displays are a technology rising in popularity among private individuals but also companies. With this rise comes new possibilities which opens up for new ways of interaction in the real world together with the virtual. This thesis introduces some of these interactions between the real world and the virtual, displayed on the HoloLens platform. It introduces the approach of designing and implementing a system which would be used in the wood working industry, especially aiming for truss assembly productions lines. A proof-of-concept was implemented and evaluated by a pool of testers in four different environments. The evaluation showed that participants were task efficient when understanding what to do, e.g., finding objects and placing them on surfaces using AR-based system. Lastly, the toughest criteria to fulfil was the enjoyments criteria; however, the user study shows that 5 out of 5 users enjoyed working with AR and could see the potential with the technique in their line of work.

  • 180.
    Devaprasad, Chiranth
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Tool wear investigation in Cryogenic machining of Aluminium Metal Matrix Composite2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Metal matrix composites have huge demand in the aerospace and automobile industry due to their unique characteristics. Aluminium metal matrix composites are preferred for their specific modulus. AC Floby is well known for its automotive components. Among them,the SiCAlight brake disc is a product whose material consists of reinforced silicon carbide in aluminium metal matrix composite. The SiCAlight brake disc, as the name suggests offers a lightweight brake disc and with low to almost zero brake dust compared to conventional cast iron. Aluminium silicon carbide is difficult to machine with excessive tool wear, which increases the production cost. In this work, the main goal is to investigate the effect of cryogenic machining on aluminium metal matrix composite. Experiments were carried out by machining the aluminium silicon carbide with 20%wt using an uncoated tungsten carbide insert. Four conditions were tested namely dry, flank, rake, and dual cooling (combination of rake and flank face cooling simultaneously). This work aimed to investigate in particular the effects of different cooling conditions on tool wear compared to dry machining condition. The results showed that the dry machining had less flank wear compared to other cooling conditions at all cutting speeds. Nevertheless, cryogenic flank cooling helps in the reduction of BUE height at higher cutting speeds. Further analysis was carried out to observe the wear mechanisms. It was found that dominant wear mechanisms are abrasion and adhesion. It was also concluded that the cooling effect doesn’t have an influence on wear mechanisms. Further study led to the finding that under given cutting conditions, cutting speed has more influence than the added external cooling using liquid nitrogen.

  • 181.
    Devotta, Ashwin Moris
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Sandvik Coromant AB, Sandviken, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Löf, Ronnie
    Sandvik Coromant AB, Sandviken, Sweden.
    Espes, Emil
    Sandvik Coromant AB, Stockholm, Sweden.
    Quantitative Characterization of Chip Morphology Using Computed Tomography in Orthogonal Turning Process2015In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 33, p. 299-304Article in journal (Refereed)
    Abstract [en]

    Abstract The simulation of machining process has been an area of active research for over two decades. To fully incorporate finite element (FE) simulations as a state of art tool design aid, there is a need for higher accuracy methodology. An area of improvement is the prediction of chip shape in FE simulations. Characterization of chip shape is therefore a necessity to validate the FE simulations with experimental investigations. The aim of this paper is to present an investigation where computed tomography (CT) is used for the characterization of the chip shape obtained from 2D orthogonal turning experiments. In this work, the CT method has been used for obtaining the full 3D representation of a machined chip. The CT method is highly advantageous for the complex curled chip shapes besides its ability to capture microscopic features on the chip like lamellae structure and surface roughness. This new methodology aids in the validation of several key parameters representing chip shape. The chip morphology’s 3D representation is obtained with the necessary accuracy which provides the ability to use chip curl as a practical validation tool for FE simulation of chip formation in practical machining operations. The study clearly states the ability of the new CT methodology to be used as a tool for the characterization of chip morphology in chip formation studies and industrial applications.

  • 182.
    Dhruv, Raja
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Impact Toughness of alloy 718-built using Laser Powder Bed Fusion2020Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project was done on the research of Laser Powder Bed Fusion built Alloy 718. The main work was the metallographic analysis of the samples using both optical and scanning electron microscope. Different sets of heat treatments and their effect on the microstructure was studied. Also, each sample was built in two orientations, vertical and horizontal, to find any changes in properties, phase composition and/or microstructure between the two to find out orientation dependence of the process if any. The main mechanical property concerned was the impact toughness. It was found that the ductility and impact toughness is higher for the vertically built samples. Heat treated samples had larger grain sizes than the as-built material. As seen in H1(SR(1065) + HIP (1121) + ST1 (1065) + ST 2 (954) + Aging1(760+649)), due to solution treating the material twice and longer exposure of the material to high temperatures, plate-like delta phase begins to form on the grain boundaries which is absent in materials that undergo heat treatments H2 (HIP (1121) + ST5 (1025) + Aging2 (760)) and H3(HIP GQ (1121) + Aging1 (760+649)(combined HIP and HT in HIP furnace). Intergranular delta phase is often considered beneficial to the material due to its ability to restrict grain growth during heat treatments which contributes to its hardness. In line with this argument, the hardest sample was the H1 heat treated sample with the lowest grain size among all the heat treated samples. Though the reason behind the low grain size was attributed not to the presence of delta phase but mainly due to the stress relieving done in H1 which removes the driving force for grain growth.

  • 183.
    Doski, Rojin
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Processhantering och effektivisering av kassationer med hjälp av automatisering: En fallstudie utförd på Adient Sweden AB2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis aims to examine how process management in the form of scrap outcomes can be streamlined and handled in production. The study also intends to account for how deviations can be reported in process flows in a more efficient way. Using empirical data from Adient in parallel with relevant literature study, the theory has been presented how this can be implemented in production.

    In the process mapping of the current situation, a current situation analysis has been applied to Adient Sweden AB's local process flows in production Subsequently, observations and interviews have been applied to identify improvement proposals. Through continuous interviews with management, the author has been able to focus on only what the company were in flows. Adient strives to have standardized workflows on the management of scrap outcomes so that all departments in the company follow the same concept. To achieve the company's vision, it is important to ensure that flows are newly conceived and that new module proposals in the business systems are evaluated. As the scrap outcomes lack an organized and structural process flow, the focus has been on presenting a more standardized workflow with digital improvement proposals.

    The work results in Adient implementing a new scrap module in its business system for continuous improvement and to counteract ruthlessness about scrap outcomes that are not tracked and controlled.

  • 184.
    Dubravina Svensson, Polina
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Livscykelstudie av cykelramar tillverkade av kolfiberkomposit, aluminium och stål2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Borås Cykelfabrik builds, develops and sells bicycles. They offer mountainbikes, gravel/cross and touring bikes made of carbon fiber composite and aluminum alloy.

    The Corona pandemic has contributed to increased bicycle sales by 30% during 2019-2020. Borås Cykelfabrik therefore sees a great potential for expanded sales of bicycles. Society's environmental awareness also contributes to increased customer demand for sustainably produced bicycles. Therefore, there is an interest from the company to compare carbon fiber composite, aluminum and steel materials in bicycle frames in terms of environmental impact.

    This life cycle study aims to provide a theoretical basis for the environmental impact of the bicycle framework. The study can also be used for further LCA on the complete bicycle.The starting point of the study is the weight of the bicycle frame of each material. Material-, manufacturing-, transport- and recycling data were collected for analysis of environmental impact. The Granta EduPack 2020 database was used for information about energy consumption and carbon dioxide emissions.

    The results show that steel alloy bicycle frames have the least environmental impact, compared to carbon fiber composite and aluminum alloy. The greatest relative energy use and carbon dioxide emissions occur during the material production phase.

  • 185.
    Edigbe, Gabriel Ogheneluona
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Assessment of Arc Stability Features for Selected Gas metal Arc Welding Conditions2021Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Stability is a key indicator of the efficiency of the gas metal arc welding (GMAW) operation,and it is linked to other quality indicators like spattering and weld formation. This thesis work describes methods of assessing arc stability for selected GMAW conditions. It focuses on stability characterisation and defines the relationships between process stability and influencing factors.

    Welding tests were performed using two selected transfer modes being the spray and the pulse transfer modes to characterize stability and develop processes further for better overall performance. Short circuit was not included because it exceeds the scope of thesis even though it is also of interest for ESAB to characterize stability using this mode. For the spray transfer, stability characterization was carried out by analyzing voltage disturbances (explosions) in the form of voltage peaks (negative and positive) since the explosions occurring in the arc corresponded to the voltage fluctuations during welding. These tests were performed on a sandblasted carbon steel plate, using carbon steel wire in diameter 1,0 mm, gas mixture of 82%CO22/18%Ar, and with three different voltage values (29V, 31,5V and 32,5V) and inductance control settings (0, 60 and 95). This scope of parameters was selected in order to simulate certain range of stability behavior, so it was possible to analyze the factors correlated to stability, their relevance in influencing stability, and consequently to define a calculation algorithm for the determination of stability.Also, stability was calculated and scored based on two scoring indices. The first was stability scoring based on performance character (spatter presence, hardness of arc, smoothness of process) The other was stability scoring based on regularity of the process (repeatability and steadiness of electrical parameters, variations of process disturbances, uniformity of the process). These two different stability characteristics are recognized in industry within ESAB applications, and the process regularity represents the major proportion of this characterisation.

    For the pulse transfer, stability characterization was carried out by analyzing and comparing two different current waveforms in terms of evaluating effects on stability. The linear waveform, which is the conventional type of waveform, was compared to an exponential waveform (with optimised droplet detachment). Results obtained from spray arc analyses showed that stability has certain indicators that are measurable by signal and image processing, and these were further analysed. Voltage disturbances were correlated to explosions observable during the process. Actual values of positive and negative voltage peaks, voltage amplitudes, and their average values and standard deviations in selected analysed time showed to be relevant indicators to characterise stability of the process. Variations of indicated voltage signals related to explosions showed to have complex patterns in terms of their waveforms. So, all these were analysed step by step and consequently selected for characterisation (calculation of stability) in the welding conditions that were selected in the scope of this project. Exact determination of stability formula was established, and this can be further developed in ESAB conditions in terms of automating the calculation with possibility of variable setting of calculated factors and ranges for specific analysed welding conditions.

    The results for the pulse arc confirmed that the exponential waveform when compared to the linear waveform showed better stability conditions. It also showed that an important factor is the duration of the base current time and its standard deviation over selected analysed time, which optimised the droplet detachment mechanism.I

    n conclusion, this approach of characterizing stability has been shown to be successful in terms of having a reasonable capacity to evaluate distinct elements that are acting in the process and determining overall stability.

  • 186.
    Edstorp, Marcus
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    A Comparison between Moving Mesh Implementations for Metal Deposition Simulations2006In: Proceedings of the Nordic COMSOL Conference: Lyngby, Denmark, 2006, p. 107-110Conference paper (Other academic)
  • 187.
    Edstorp, Marcus
    University West, Department of Engineering Science, Division of Production Engineering.
    Weld Pool Simulations2008Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This investigation is devoted to the study of welding and its effect on the workpiece, focusing on the thermo and fluid dynamical phenomena occuring during a autogenous or nonautogenous arc fusion welding process. Its aim is to simulate the behaviour of the weld pool and analyze the consequence of the solid-liquid phase change, thus obtaining a methodology for predicting the appearance of weld defects related to solidification and cooling. In order to accomplish this, we solve equations governing a number of continuum mechanical and electromagnetical quantities, as well as consider the motion of the freely moving boundary of the weld pool. Since the state of these quantities is strongly influenced by phenomena such as arc and droplet impingement, non-isothermal phase change, surface tension, Marangoni forces and Lorentz forces, much effort is necessarily devoted to the modelling of the corresponding fluxes and sources, as well as to the implementation of computationally efficient techniques for simulating the geometrical deformation of the workpiece, which in our setting is entirely determined by the motion of the weld pool surface.

    Common to all arc fusion welding processes is the employment of a welding arc. Many techniques rely on the arc to clean and shield the workpiece during the process, however in this study we consider it to be its main purpose to cause the local increase of thermal energy that is required for the establishment of the weld pool, and also to exert the mechanical forces that provoke the subsequent fluid flow which enhances heat transfer and facilitates weld penetration. The physics of the welding arc itself is quite intricate, and although the modelling of the arc is not the prime objective of this research project, we conclude that arc forces act on the pool surface, and that the investigation of the arc behaviour is important insofar that it provides input to the pool model and thus enables a more accurate prediction of the quality of the weldment that is created once the pool has solidified

  • 188.
    Edstorp, Marcus
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Charles, Corinne
    University West, Department of Engineering Science, Division of Production Engineering.
    A Finite Element Methodology for Simulating the Influence of Process Parameters on the Phase Transitions in a GTA weld2009In: Proceedings of the 15th International Conference on the Joining of Materials, 2009Conference paper (Other academic)
  • 189.
    Edström, Johan
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Hammar, Samuel
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Framtagning av beräkningsmodell för uppvärmningssystem: med fokus på kombinationen fjärrvärme och frånluftsvärmepumpar2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As a result of the EU's environmental 2020 goal, the Swedish government and municipal boards has put up internal goals to reduce energy consumption. EU 2020 goal aims to reduce energy consumption in Europe by 20 percent by the year 2020 from that the target was set in 2010.

    At the municipal level, this has meant that private but mainly public housing properties have been required to review their energy use. The work in this report is based on one of the savings measures that have been taken, which is to supplement existing district heating systems with exhaust air heat pumps. The project aims to develop a calculation model for evaluation and computation for this type of system.

    To create a reliable basis for decisions, efforts were made to produce just calculations. Existing computational models are focused on economic factors and thus takes little consideration of technological aspects and environmental factors. The aim of the work has been to create a computational model which more closely reflects the real situation and demonstrates a more informative decision basis.

    The work began with a literature review which included relevant research and basic facts about exhaust air heat pumps and district heating systems. The calculation model has been developed continuously during the project in which new functions and new information constantly has been added.

    The project has resulted in a working computational model which includes many more parameters than previous reviewed models. Together with the client three sub goals were set up for the model, these were:

    •  To intuitively present information and data.
    •  To create a transparent structure which is simple to follow.
    •  To create a flow through the model, which follows a desired work process.

    These goals are considered to have been fulfilled in the developed calculation model, however, it's possible to further develop this model. The model could, for example, be supplemented with more automated optimization calculations and be adjusted to handle other kinds of heating systems.

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  • 190.
    Edvinsson, Åke
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Förbättringsförslag för kyl och värmesystemet i en GasHub-anläggning för Stirlingmotorer2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In 1816 the Stirling engine was invented and has since been tested in a variety of applications. Cleanergy using Stirling technology in its solar and gas plants to produce electricity and heat. The goal of this work is to develop proposals for an energy-efficient way to control the cooling of a GasHub plant to the desired temperatures and draft proposals on combined heat and power solutions known as CHP (Combined Heat and Power). The method of work was to identify how the system looks like, customer visits and the development of proposals for improvement. A GasHub is a facility built out of a container in which this has been designed to connect and place GasBox units. A GasBox is a unit of the Stirling engine, generator and gas burners. A necessary feature of a Stirling engine is its cooling, partly to engine components is not too hot and partly to cool the heated gas. This is because the pressure and volume of gas to be reduced in the cooling phase of the motor to rotate. Cooling and heating system in GasHub linking together all GasBox where glycol mixed cooling water rotates around in a loop. The heat from the Stirling engines is transmitted in the heat exchanger to the cooled coolant from GasHub and in this way is reduced when the heat in the cooling system to Stirling engines. A GasBox produces about 7,2kW electricity when it runs on biogas and 20kW heat energy. The customers who have chosen to install the heating system uses this mainly to heat buildings and land heat outdoors to keep this clean of snow and ice. A GasHub 5 plant produces about 36 kW of electricity. According to the data Cleanergy has estimated the average parasitic loads to about 1.5kW or about 4% of the total energy production. A study was conducted on a GasHub facility in Ulricehamn to, among other things to find out how the customer experienced how large parasite loads were and what could be the reason for this. The calculations are carried out shows that the circulation pump is correctly sized. The pump needs to cope with a delivery height of 9 meters and need a flow of 8.6 m3 / hour. The result has three suggestions for improvement of control system for the cooling presented. The first proposal is control by the temperature, then the circulation pump speed is controlled so that a temperature difference of 12 degrees from the input heat to GasBox and out of this. The second proposal involves driving at various differential pressures for various operating conditions. The third proposal involves installing a thermostat on GasBox to regulate the heat out of it. The improvement proposal is about reducing waste heat and energy are proposed to isolate pipes in GasHub. Calculations show that it is possible to save 35kWh heat-energy per day. The proposals of the CHP solutions suggested that the heat can be used for air conditioning if an adsorptions-chiller is used. It is further proposed that the heat stored in the bedrock and cooling taken from there to cool GasHub. The discussion and analysis section of the report assesses improvement proposals and temperature differential regulation proposal is considered that it is relatively easy to implement and is the most optimal for the circulation flow and lower energy consumption. Among CHP proposals considered to be relatively easy to install an adsorptions-chiller to use the heat to the air. Furthermore, the chapter raises the question whether it would be possible to cool using a lower flow in the system because this could save more energy. The question of whether it would be possible to raise the temperature in the engine of a major gas coolers are used are highlighted. The conclusion of the report states that GasHub is today a fully functional facility for the production of electricity and heat, however, that there is much potential for improvement in the plant. It is found that rules the proposals is estimated to halve the energy consumption of the circulation pump.

  • 191.
    Eggertsen, P. -A
    et al.
    University of Technology, Div. of Material and Computational Mechanics, Dept. of Applied Mechanics Chalmers.
    Mattiasson, Kjell
    University of Technology, Div. of Material and Computational Mechanics, Dept. of Applied Mechanics Chalmers.
    Larsson, Mats
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    A comprehenisve analysis of benchmark 4: Pre-strain effect on springback of 2D draw bending2011In: AIP Conference Proceedings, Seoul, 2011, Vol. 1383, p. 1064-1071Conference paper (Refereed)
    Abstract [en]

    In order to be able to form high strength steels with low ductility, multi-step forming processes are becoming more common. Benchmark 4 of the NUMISHEET 2011 conference is an attempt to imitate such a process. A DP780 steel sheet with 1.4 mm thickness is considered. In order to understand the pre-strain effect on subsequent forming and springback, a 2D draw-bending is considered. Two cases are studied: one without prestrain and one with 8% pre-stretching. The draw-bending model is identical to the "U-bend" problem of the NUMISHEET'93 conference. The purpose of the benchmark problem is to evaluate the capability of modern FE-methods to simulate the forming and springback of these kinds of problems. The authors of this article have previously made exhaustive studies on material modeling in applications to sheet metal forming and springback problems, [1],[2],[3]. Models for kinematic hardening, anisotropic yield conditions, and elastic stiffness reduction have been investigated. Also procedures for material characterization have been studied. The material model that mainly has been used in the current study is based on the Banabic BBC2005 yield criterion, and a modified version of the Yoshida-Uemori model for cyclic hardening. This model, like a number of other models, has been implemented as User Subroutines in LS-DYNA. The effects of various aspects of material modeling will be demonstrated in connection to the current benchmark problems. The provided material data for the current benchmark problem are not complete in all respects. In order to be able to perform the current simulations, the authors have been forced to introduce a few additional assumptions. The effects of these assumptions will also be discussed. © 2011 American Institute of Physics.

  • 192.
    Ehnberg, Jimmy S. G.
    et al.
    Chalmers University of Technology, Department of Electric Power Engineering.
    Bollen, Math H.J
    Chalmers University of Technology, Department of Electric Power Engineering.
    Simulation of global solar radiation based on cloud observations2005In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 78, no 2, p. 157-162Article in journal (Refereed)
  • 193.
    Ehnberg, Jimmy S.G.
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Autonomous power systems based on renewables: On generation reliability and system control2007Doctoral thesis, comprehensive summary (Other academic)
  • 194.
    Ehnberg, Jimmy S.G.
    et al.
    Chalmers University of Technology,Department of Electric Power Engineering.
    Agneholm, Evert
    Gothia Power Ab, Göteborg.
    Reverse Motor Control for CCLs in AC Hybrid Minigrids2006In: 3rd European conference on PV-hybrid and Mini-grid, 2006, p. 138-143Conference paper (Refereed)
  • 195.
    Ehnberg, Jimmy S.G.
    et al.
    Chalmers University of Technology,Department of Electric Power Engineering.
    Bollen, Math H.J.
    STRI Ab,Ludvika.
    Generation Reliability for Small Isolated Power Systems entirely based on Renewable Sources2004In: Power Engineering Society General Meeting, 2004. IEEE, 2004, p. 2322-2327 Vol 2Conference paper (Refereed)
  • 196.
    Ehnberg, Jimmy S.G
    et al.
    Chalmers University of Technology, Department of Electric Power Engineering.
    Bollen, Math H.J
    STRI AB, Ludvika, Sweden.
    Reliability of a small power system using solar power and hydro2005In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 74, no 1, p. 119-127Article in journal (Refereed)
  • 197.
    Einarsson, Linus
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Fixtur till 30k TEC: Konceptframtagning2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report regards the manufacturing process of 30K TEC, an ingoing part to the PW1000 engine from Pratt & Whitney. The complexity of the parts geometry and the material makes for a problematic manufacturing process. The part is strapped down into a milling fixture which holds the part in place. The part is then machined with a cutting process to it final geometry. The process produces a high temperature on both the tool and part which leads to a geometry change in the part. Due to the geometry changes vibrations occur and affects the result on the part with poor surface and shortened tool life. In this report a concept is established for a milling fixture that accounts for the manufacturing aspects named above. The report and work follow the general concept development process from establishing the customer´s needs to generating concepts and selecting the final concept.

    The work resulted in a concept for a fixture witch in theory meets the customer´s needs and favors the process. The fixture holds the part down with help of pneumatics and controls the geometry changes with vacuum to prevent vibrations. To evaluate if the fixture achieves the established target specifications further work is needed. The fixture or parts of it needs testing in practice before the result can be fully evaluated.

  • 198.
    Ek, Johan
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Frisk, Kasper
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Förbättringsarbete för lagerhantering2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In recent years, material transfer and inventory management have had a greater impact on the profitability of manufacturing companies. By optimizing inventory- and material handling as well as implementing logistics lift within flow optimization, the conditions for companies to be sustainable and competitive are created. As companies reorganize or invest in material management, extensive information gathering and careful analysis of current operations are required to identify the optimal solution. The company on which the case study is conducted is Norautron AB, a global electronics company based in Vänersborg. The case company intends to invest in a new warehousing system during an upcoming reorganization and therefore needs to identify what improvement opportunities exist in the current material flow and what requirements need to be set for a new warehousing system.The survey design for this study is a case study where interviews, observations and measurements along with a theoretical frame of reference based on scientific articles and student literature form the basis of the study's results. The empirical data showed that there are two major improvement opportunities for the company; long delivery, picking and closing times and low volume and surface utilization. A cost computation was created for these improvement opportunities and they were broken down into root cause using quality tools.The study resulted in the aforementioned improvement possibilities and root causes based on the empirical material, but also a requirements specification consisting of system- and improvement requirements. The system requirements are aimed at numerical factors that affect or limit a new inventory system while the improvement requirements are aimed at improvements that a new inventory system needs to solve or partially solve in order for the investment to be economically justifiable.The conclusion that emerged is that there are currently two main improvement possibilities in Norautron's material flow that are in line with the previously described theory in the logistics field. The study also shows that a new inventory system must be adapted to many different factors without the system generating annual total costs in excess of SEK 300 000, unless these costs are economically justifiable for other reasons that the company considers to be of great importance. The company's next step should therefore not be a new investment, but rather a further development of the existing inventory system.

  • 199. Eklöf, J.
    et al.
     Hamelryck, T.
    Lundh Snis, Ulrika
    University West, School of Business, Economics and IT, Divison of Informatics.
    What leaders require to deploy AI in manufacturing companies: An interdisciplinary and mixed methods approach2022Conference paper (Refereed)
  • 200.
    Ekman, Viktor
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Utveckling av koncept till premium skärmväggssystem2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor's thesis has been carried out with AH Productions AB in Åmål. The report presents the work developing a final concept, cost analysis and life cycle analysis for a premium screen wall system. The company's existing screen wall system consists of doors and walls in an environmentally friendly homogeneous compact laminate which if fitted with profiles in natural anodized aluminum, together with support legs and optional components. The purpose of the bachelor's thesis is to increase the company's competitiveness by development of a premium version of their existing screen wall system that satisfy new customer requirements and requests.

    With customer requirements and requests given from the company a requirements specification was compiled. Based on requirements specification a concept development was preformed where solutions were generated to fulfill customer requirements. The solutions were then combined into concepts. The concepts were screened first through a coarse screening and then a concept screening where they were evaluated against the current screening wall and select criteria. Remaining concept was evaluated in a concept matrix to get the winning concept. The winning concept was further developed with hand calculations, drawings, 3D modeling and material choice to a final concept.

    Each component in the final concept a manufacturing choice was performed. With material and manufacturing choices a production cost could be calculated with the program CES Edupack, and then a productions cost for the complete screen wall system. Finally, lifecycle analysis was preformed to calculate the environmental impact from producing the final concept with the chosen manufacturing process and material choice.

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