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  • Börjesson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    SNMP-Proxy för SMF marknaden: Kan SNMP-proxy vara lösningen för att realisera SNMP som tjänst till SMF marknaden?2019Independent thesis Basic level (university diploma), 80 credits / 120 HE creditsStudent thesis
  • Jan, Petra
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Thermomechanical characterisation of newly developed UHMWPE composites2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ultra high molecular weight polyethylene (UHMWPE) is a polymer commonly used in various applications, particularly in hip joint replacements. Despite its good performance, it is susceptible to oxidation degradation, which can be mitigated with the addition of vitamin E, and to excessive wear against metal countersurfaces, which can potentially be improved with the addition of nanoparticles. In this work, sixteen newly developed UHMWPE nanocomposites with different nanofillers (multi-walled carbon nanotubes, graphene oxide and nanodiamonds), blended with and without vitamin E, and both irradiation crosslinked and non-crosslinked were studied. Thermomechanical characterisation (dynamic mechanical analysis and thermogravimetric analysis) and tribological pin-on-disc testing showed that both nanofillers and the addition of vitamin E ensured improved the performance of the nanocomposites compared to the virgin UHMWPE. Vitamin E improved the oxidative and thermal stability of UHMWPE, decreased the wear and increased the coefficient of friction. The nanoparticle reinforcements contributed to improved thermal stability to some degree and decreased the wear. Crosslinking was also shown to result in improved thermomechanical performance, although it appears that the addition of vitamin E inhibits the crosslinking process.

  • Lindberg, Liv-Johanna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Ständiga förbättringar genom teorin kring single- och double-loop learning: En fallstudie av Skanskas arbetssätt och strukturer2019Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [en]

    Which method is the best to collect all the employees’ information, data and experiences? Furthermore, how does all the information reach the whole organization? These questions have been investigated for a long time in the building sector. Earlier studies and graduation works have looked into experience feedback and continuous improvement and it is something that needs to be more investigated since it still does not work to its fully potential.

     

    This study looks into one of Sweden’s biggest construction entrepreneurs, Skanska, and how the organization can be compared to a learning organization. The study investigates two main things; one is how the employees uses experience feedback and how they find experiences in the company. The other part looks into one of the main structures in the company that focuses on experience feedback, called PiV-meetings, World Class Projects-meetings.

     

    The purpose with the study is to evaluate Skanska Sweden’s work with experience feedback today and how it could be developed. Evaluate if it consists parts in the flow of experiences that does not work to its fully potential, which can prohibit the distribution of experiences out in the whole organization. The purpose is also to look into PiV-meetings and see if the meetings is a good tool for experience feedback.

     

    The study has been conducted as a qualitative study and has been focusing on a large region in Sweden. Seven interviews were held whereas six of them was so called semi-structured interviews and one of them was a starting interview to get an understanding of the organization and its work regarding experience feedback.

     

    The result shows two focuses for the organization. One is to be clearer with the purpose for the PiV-meetings and be a little harder with consequences for the ones who do not follow Vsaa. The other result shows that based on the theoretical base in this study, single- and double-loop learning, Skanska needs to be a little better with the reach of the PiV-meetings results. Making sure that they really reaches the highest “top” in the organization and therefore creates a double-loop learning.

     

    The recommendation from this study is to follow up the PiV-meetings and really see that the double-loop learning occurs in the organization. The result based on the studied region shows that in the region does the experience feedback work well, but it needs to be good in the whole organization to classify Skanska as a complete learning organization.

  • Tošić, Marko
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Model of Thermal EHL Based on Navier-Stokes Equations: Effects of Asperities and Extreme Loads2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A common approach in numerical studies of elastohydrodynamic lubrication (EHL) is based on solving the Reynolds equation that governs pressure distribution in thin lubricant films. The Reynolds equation is derived from the Navier-Stokes equations by taking assumptions that are considered valid when the thickness of the lubricant film is much smaller than its length. A massive increase in the computing power over the last decades has enabled the use of CFD (computational fluid dynamics) approach, based on the Navier-Stokes equations, in solving the EHL problem. Comparisons between the CFD and Reynolds approach have generally shown very good agreement. Differences can occur when the thin film assumptions of the Reynolds equation are not applicable. In this study, a CFD approach has been chosen with the aim of investigating effects of asperities and rheology at high loads on the behavior of the thin EHL films. A high quality mesh was generated in ANSYS ICEM CFD, while ANSYS Fluent has been employed in solving the Navier-Stokes equation by finite volume method (FVM). For EHL modeling, a set of user-defined functions (UDFs) were used for computing density, viscosity, wall temperature, heat source and elastic deformation of one of the contacting surfaces. Two lubricants were used, a commonly used oil in CFD analyses of EHL and Squalane. Non-Newtonian fluid behavior and thermal effects were considered. For Squalane, the two rheology models, Ree-Eyring and Carreau were compared. Squalane has been chosen in this study since it is one of the rare fluids with known parameters for both rheology models. Finally, the influence of surface roughness was explored for the cases of a single asperity and a completely rough wall. A surface roughness profile is generated in MATLAB by using the Pearson distribution function. In the cases where the surfaces are assumed to be completely smooth, the obtained results at the pressure of about 0.5 GPa closely correspond to literature, both in the case of Newtonian and non-Newtonian fluid behavior. At the pressure of about 1 GPa, severe shearing of the lubricant film has been noticed, characterized by a pronounced shear-band and plug flow. It was found that the choice of viscosity and rheology models has a large influence on the obtained results, especially at the high pressure levels. Finally, it was discovered that the developed CFD model of EHL has a great potential in studying the effects of surface roughness on the lubricant film behavior.

  • Lartey, Jerry
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Effective Vulnerability Management for Small Scale Organisations in Ghana2019Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Most Small and Medium scale Enterprises (SMEs) in Ghana are notparticularly anxious about the consequences of inadequacy or lack of anyform of vulnerability management operation in their normal businesspractices. This case study research explores how a local Internet ServiceProvider (ISP) in Ghana and its local client-base can manage vulnerabilitieswith a targeted patch management practise integrated into their operations.To answer the research question “How can a SME local Internet ServiceProvider (ISP) in Accra, Ghana, assist their local customer base to integrateeffective cybersecurity vulnerability management into their operations?“,This case study comprised the Subject Matter Expert of one local ISP as well as4 other technical Subject Matter Experts of the ISP’s clients about their patchmanagement operations. This case study research revealed that most SMEs donot consider vulnerability management as a key concern in the operation oftheir organisation and therefore, proposes a way to highlight the importanceof vulnerability management whiles doing so at a cost-effective manner. Theimplications of targeted cybersecurity patch management for the local ISP andtheir client-base is also addressed by this thesis research.

  • Terekhov, Georgy
    Luleå University of Technology, Department of Arts, Communication and Education.
    Orgelklang: En studie i praktisk orgelkännedom2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta arbete har jag studerat orgelklang under barocken och romantiken. Med hjälp av litteratur om orgelkunskap, notutgåvor och videoinspelningar har jag laborerat vid Orgel Acusticum vid Luleå tekniska universitet, för att hitta passande klanger för verk av Couperin, Bach, Liszt och Reger. I slutet av arbetet har jag producerat fyra inspelningar för att dokumentera resultaten från mina laborationer vid Orgel Acusticum. Jag har arbetat med olika tidstypiska orgelregistreringar för den franska klassiska orgeln, den tyska barockorgeln, den högromantiska orgeln och den tyska senromantiska orgeln. En vanlig och viktig uppgift för utövande organister är att kunna hitta passande registreringar för den repertoar som ska framföras. Det finns många orgelstycken som inte har några anvisningar om önskad klang. Detta inspirerade mig att söka mer kunskap om registreringspraxis och orgelklang under olika epoker.

  • Nordström, Daniel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Applicability of modern graphics libraries in web development: How may current graphics APIs that allow GPU-rendered web content be better inorporated for use in modern web application production?2019Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    This thesis presents an exploration into current web browser technologies for graphicsdevelopment, and offers a framework-like solution to integrate WebGL basedgraphical features into any web application based on those findings. It is builtlargely of the 2017 investigative graduate work done at Explizit Solutions (an ITfirm based in Skellefteå, Sweden), where the goal was to discover how 3D graphicstechnology in web browsers could be incorporated into and improve the front-endof their booking system services. A refined version of the solution produced in thatwork is presented, discussed and evaluated in this dissertation along with the investigativework done to produce it.

  • Marklund, Hanna
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Supersonic Retro Propulsion Flight Vehicle Engineering of a Human Mission to Mars2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A manned Mars mission will require a substantial increase in landed mass compared to previous robotic missions, beyond the capabilities of current Entry Descent and Landing, EDL, technologies, such as blunt-body aeroshells and supersonic disk-gap-band parachutes. The heaviest payload successfully landed on Mars to date is the Mars Science Laboratory which delivered the Curiosity rover with an approximate mass of 900 kg. For a human mission, a payload of magnitude 30-50 times heavier will need to reach the surface in a secure manner. According to the Global Exploration Roadmap, GER, a Human Mission to Mars, HMM, is planned to take place after year 2030. To prepare for such an event several technologies need maturing and development, one of them is to be able to use and accurately asses the performance of Supersonic Retro Propulsion, SRP, another is to be able to use inflatable heat shields.

    This internal study conducted at the European Space Agency, ESA, is a first investigation focusing on the Entry Descent and Landing, EDL, sequence of a manned Mars lander utilising an inflatable heatshield and SRP, which are both potential technologies for enabling future landings of heavy payloads on the planet. The thesis covers the areas of aerodynamics and propulsion coupled together to achieve a design, which considers the flight envelope constraints imposed on human missions. The descent has five different phases and they are defined as circular orbit, hypersonic entry, supersonic retropropulsion, vertical turn manoeuvre and soft landing. The focus of this thesis is on one of the phases, the SRP phase.

    The study is carried out with the retro-thrust profile and SRP phase initiation Mach number as parameters. Aerodynamic data in the hyper and supersonic regime are generated using Computational Fluid Dynamics, CFD, to accurately assess the retropropulsive performance. The basic concept and initial sizing of the manned Mars lander builds on a preliminary technical report from ESA, the Mission Scenarios and Vehicle Design Document. The overall optimisation process has three parts and is based on iterations between the vehicle design, CFD computations in the software DLR-Tau and trajectory planning in the software ASTOS. Two of those parts are studied, the vehicle design and the CFD,to optimise and evaluate the feasibility of SRP during the descent and test the design parameters of the vehicle. This approach is novel, the efficiency and accuracy of the method itself is discussed and evaluated. Initially the exterior vehicle Computer Aided Design, CAD, model is created, based on the Mission Scenarios and Vehicle Design Document, however updated and furthered. The propulsion system is modelled and evaluated using EcosimPRO where the nozzle characteristics, pressure levels and chemistry are defined, and later incorporated in the CAD model.

    The first iteration of the CFD part has an SRP range between Mach 7 and 2, which results in an evaluation of five points on the trajectory. The thrust levels, the corresponding velocity, altitude and atmospheric properties at those points can then be evaluated and later incorporated in ASTOS. ASTOS, in turn, can simulate the full trajectory from orbit to landing including the CFD data of the SRP phase. Due to time limitation only one iteration of the vehicle design and the SRP range was completed. However, the goals of the study were reached. A first assessment of SRP in Mars atmosphere has been carried out, and the aerodynamic and propulsive data has been collected to be built on in the future. The results indicate that the engines can start at a velocity of Mach 7. They also show consistency with similar studies conducted in Earths atmosphere. The current vehicle design, propulsion system and SRP range can now be furthered, updated and advanced in order to optimise the different descent phases in combination with future results from ASTOS.

  • Glans, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Klena dimensioner vid etappglödgning2019Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
  • Hero, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Polymerkoncentrationens inverkan på härdresultatet av seghärdningsstål 356D och 495B.2015Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [sv]

    De ökande kraven på kvalité från kunder och ett allt strängare regelverk från myndigheter gällande miljön, har lett till att Ovako Sweden AB Hällefors har planer på att introducera polymer (Aquatensid) som nytt kylmedel i sin Induktionshärdningslinje. Detta för att minska risken för sprickbildning i materialet till följd av för stora spänningar, samtidigt som vattnet byts ut mot ett resultatmässigt bättre alternativ. Tidigare studier med lovande resultat har utförts inom området och detta arbete inriktar sig på att finna en balanserad koncentrationshalt av polymer i blandning med vatten som kan passa för hela Ovakos seghärdade sortiment.Tester har skett på två av de vanligaste stålsorterna (Ovako 356 och Ovako 495) dessa har gemensamt att de är relativt höglegerade stål i Ovakos sortiment. Stålsorterna har härdats i en kammarugn vid höga temperaturer och sedan kylts under omröring i ett bad av vattenblandad polymer vid varierande koncentrationer. Noggrann fysikalisk provning innefattande hårdhetsprofiler i Vickers, mikroskopering i ljusmikroskop och Svepelektronmikroskop (SEM). Detta för att se om eventuella skillnader i strukturen uppkommit, som kan ge tendenser till sprickuppkomst och försämrad härdbarhet. Resultaten av testerna visar att för stålsort 495B kan jämna hårdhetsintervall uppnås över de olika koncentrationerna, men att man får en större variation då man kyler 356D.

  • Zetterholm, Jonas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mossberg, Johanna
    RISE Research Institutes of Sweden, Bioeconomy.
    Joakim, Lundgren
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Evaluating investments in integrated biofuel production - factoring in uncertainty through real options analysis2019In: PROCEEDINGS OF ECOS 2019 / [ed] Wojciech Stanek, Paweł Gładysz, Sebastian Werle, Wojciech Adamczyk, 2019, p. 1921-1932Conference paper (Refereed)
    Abstract [en]

    In the endeavour to reduce CO2 emissions from the transport sector, biofuels from forest industry by-products are key. The adaptation of forest-based biorefinery technologies has so far been low which can partly be attributed to uncertainties in the form of policy instability, market prices, and technology costs. These uncertainties in combination with technology learning, which can be expected to reduce future investment costs, could make it favourable to postpone an investment decision. When applying real options theory, it is recognised that there is an opportunity cost associated with the decision to invest, since the option to wait for more favourable market conditions to occur is forfeited. In traditional discounted cash flow analysis, the impact of uncertainty and the value of reducing it (e.g. by waiting), is usually not taken into consideration. This paper uses a real options framework that incorporates the option to postpone an investment to reduce market uncertainties and wait for technology learning to occur. The focus is to investigate how the usage of an investment decision rule based on real options analysis affects technology choice, the economic performance, and when in time it is favourable to invest in pulp mill integrated biofuel production, compared with using a decision rule based on traditional discounted cash flow analysis. As an illustrative case study we examine a pulp mill which has the option, but not the obligation, to invest in either of two different biofuel production technologies that both use the pulp mill by-product black liquor as feedstock: (1) black liquor gasification followed by fuel synthesis, and (2) membrane separation of lignin followed by hydrodeoxygenation. With the usage of the real options framework and the inclusion of the uncertainties regarding future market prices and investment costs, the decision to invest is made later, compared with using traditional cash flow analysis. The usage of real options also reduces the likeliness of a net loss occurring if an investment is made, as well as increases the expected economic returns, showing the added economic value of flexibility in the face of uncertain future conditions.

  • Hansen, Jonathan
    et al.
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Voland-Salamon, Virginia
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Kampmann, Tobias Christoph
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Firsching, Markus
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Samodviga, Oleksiy
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Ennen, Alexander
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Uhlmann, Norman
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth Germany.
    Sensor fusion and correlation of X-ray tomography and XRF data for drill core analysis2019In: International Symposium on Digital Industrial Radiology and Computed Tomography – DIR2019, 2019Conference paper (Refereed)
    Abstract [en]

    State of the art analysis techniques on drill cores for exploration purposes, including X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS) or Raman spectroscopy are used to derive mineralogical information. Since this sensor data corresponds to materials that occur on the surface of the core, inclusions (e.g. diamonds) cannot be detected. In addition, information outside of the measurement position is not taken into account and may lead to misinterpretation or the miss of certain elements. X-ray computed tomography (CT) and radioscopy provide data about the entire sample as well as inlying structures based on X-ray absorption. As a drawback, CT is time-consuming and the material information is not explicit.For the enhancement of geological interpretation, we propose to apply sensor data fusion techniques in order to unite both depth information as well as reliable material data information from surface measurement techniques. This leads to more substantial information of the drill core.For further insights in the feasibility we investigate the correlation of XRF data at varying abstraction levels with CT data, i.e. grey value information.The applied XRF technique involves the fact that the data is not acquired continuously but discrete point by point. This is accompanied by the circumstance that the spatial resolution of the acquired data has a different magnitude than the CT-data. Both facts result in the challenge to register the XRF data coming from a one-dimensional scan line with a micro-CT volume. The experiments must be planned in a way that location and orientation of the scan data are well-known and reproducible.In the experiments, the acquired and registered data of a defined drill core is analysed with respect to correlation and fusion capability. The experimental setup will be presented and results will be discussed.

  • Kampmann, Tobias Christoph
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alvarenga, Rodrigo A.F.
    Ghent University, Belgium.
    Sanjuan-Delmás, David
    Ghent University, Belgium.
    Lindblom, Mats
    Boliden Mineral AB, Sweden.
    Life cycle assessment of European copper mining: A case study from Sweden2019In: Proceedings of the 15th SGA Biennial Meeting, 27-30 August 2019, Glasgow, Scotland: Life with Ore Deposits on Earth, Society for Geology Applied to Mineral Deposits , 2019, Vol. 4, p. 1577-1580Conference paper (Refereed)
    Abstract [en]

    The application of the life cycle assessment (LCA) methodology in the mining sector has the potential to evaluate the environmental sustainability of the primary production of metals. As part of a wider project on developing LCA models and methods for mining, life cycle inventory (LCI) data have been collected at two European copper-producing mine sites, Aitik (Sweden) and Cobre las Cruces (Spain). Results from Aitik, including their impact analysis, identify the use of diesel and explosives, the emission of sulfur dioxide, as well as nitrogen and other emissions in the upstream supply chain of explosives and electricity, as significant contributors to the environmental impact. These outputs have influence on the impact categories Climate Change, Photochemical Ozone Formation, Acidification, as well as Terrestrial and Marine Eutrophication. Due to the increasing incorporation of LCA into legislative demands on the mining sector, mining companies need to establish the necessary infrastructure and framework to be able to provide the required data in a fast, transparent and cost-efficient manner. For this reason, some recommendations to improve communication and data management within the companies have been established from the experience gained within this project.

  • Catanoso, Damiana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Nasa Ames Research Center.
    Networked Model Predictive Control for Satellite Formation Flying2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A novel continuous low-thrust fuel-efficient model predictive control strategy for multi-satellite formations flying in low earth orbit is presented. State prediction relies on a full nonlinear relative motion model, based on quasi-nonsingular relative orbital elements, including earth oblateness effects and, through state augmentation, differential drag. The optimal control problem is specically designed to incorporate latest theoretical results concerning maneuver optimality in the state-space, yielding to a sensible total delta-V reduction, while assuring feasibility and stability though imposition of a Lyapunov constraint. The controller is particularly suitable for networked architectures since it exploits the predictive strategy and the dynamics knowledge to provide robustness against feedback losses and delays. The Networked MPC is validated through real missions simulation scenarios using a high-fidelity orbital propagator which accounts for high-order geopotential, solar radiation pressure, atmospheric drag and third-body effects.

  • Pålsson, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Insamling av lagerdata för vibrationsanalys2019Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
  • Stenberg, Ola
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Mobilbaserat detekteringssystem2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • Westring, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Successiv projektering: En kartläggning av informationsflödet2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A construction project is not the other project alike. Despite this, there are a few subprocesses that a construction project cannot do without. However, the order in which these occur and how far in time these sub-processes extend may differ depending on the project's conditions. What is common is that a construction project is initiated by its project design where project planning documents and later on construction documents are produced before the production begins. But as the construction projects shortens in time, higher demands are placed on streamlining the sub-processes. It has therefore become increasingly common for the project planning to take place gradually along the production. This master thesis is mainly based upon those interviews that were conducted during this study. The interviews were held with different peoples of either contractors or constructors. The main aim with this master thesis were to study the flow of information between those who plans the project and those who executes it, within a project were the project is been planned and designed gradually along the production. In order to form an understanding of how the flow of information work, the tools and methods used to manage information are studied in a project were the project is being planned gradually, seen from both contractors and project designers perspective. It turns out that there are relatively small differences in how the information is handled between a project that is planned gradually versus one that has been planned in advance. The tools used to spread (downstream) and report (upstream) information are the same regardless type of contract. However, what a project that is planned gradually benefits from is the choice of working methods used in the project. These working methods can facilitate the handling of the project information and the information flow created up- and downstream. The conclusions that can be drawn from this thesis are that a project with gradual planning combined with its information flow benefits from a project that is being carried out in cooperation. Which is based on the fact that the communication routes have been clearly identified at an early stage. It will both facilitating and reducing the flow of information compared to if the project would not had been carried out in cooperation. The time gains that are considered to be possible when the project is gradually planned ceases to exist if the project is not carried out in cooperation. In addition, a gain can be seen in being able to streamline the current management of how the information is being both managed and spread from the project planners. Regardless if the project has been planned prior to the production or not. However, given that work tasks such as planning/design and production are particularly close together when planning a project gradually. An efficiency in improving the project planners work while distributing the building document can increase the space for mistakes without impacting on the detailed time schedule.

  • Chohan, Neha
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Robust trajectory planning of autonomous vehicles at intersections with communication impairments2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, we consider the trajectory planning of an autonomous vehicle to cross an intersection within a given time interval. The vehicle communicates its sensordata to a central coordinator which then computes the trajectory for the given time horizon and sends it back to the vehicle. We consider a realistic scenario in which the communication links are unreliable, the evolution of the state has noise (e.g., due to the model simplification and environmental disturbances), and the observationis noisy (e.g., due to noisy sensing and/or delayed information). The intersection crossing is modeled as a chance constraint problem and the stochastic noise evolution is restricted by a terminal constraint. The communication impairments are modeled as packet drop probabilities and Kalman estimation techniques are used for predicting the states in the presence of state and observation noises. A robust sub-optimalsolution is obtained using convex optimization methods which ensures that the intersection is crossed by the vehicle in the given time interval with very low chance of failure.

  • Klang, Oskar
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Network Test Capability of Modern Web Browsers2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Web browsers are being used for network diagnostics. Users commonly verify their Internet speed by using a website, Bredbandskollen.se or speedtest.net for example. These test often need third party software, Flash or Java applets. This thesis aims at prototyping an application that pushes the boundaries of what the modern web browser is capable of producing regarding network measurements, without any third party software. The contributions of this thesis are a set of suggested tests that the modern browser should be capable of performing without third party software. These tests can potentially replace some of network technicians dedicated test equipment with web browser capable deceives such as mobile phones or laptops. There exist both TCP and UDP tests that can be combined for verifying some Quality of Service (QoS) metrics. The TCP tests can saturate a gigabit connection and is partially compliant with RFC 6349, which means the traditional Internet speed test sites can obtain more metrics from a gigabit throughput test then they do today.

  • Kurnia, Evan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics. Institution.
    High Temperature Tribology in Hot Stamping2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many automotive components are made of Al-Si coated ultra-high strength boron steel (UHSS) and are produced by hot stamping process. In this process, the workpiece is heated to an austenitizing temperature and is then formed and quenched simultaneously between the tools to achieve the desired shape and high strength. During hot stamping process, friction and wear occur which affect formability and maintenance intervals for tool replacement and repair. To repair worn tools, metal is deposited by fusion welding technique. The tribological behaviour of repair welded tool steel sliding against Al-Si coated UHSS has not been studied in detail and there is a need to investigate if the modified tool surface will affect friction and wear.

    Hot stamping, similar to many manufacturing processes, is affected by the global mega trend of digitalization and Industry 4.0. To monitor the process and optimize the control and operation are the main aims. In view of this, tribological condition monitoring is a promising approach that can allow measurement of physical properties such as vibrations, temperatures, and acoustic emission to be coupled to the tribological response of the system. The aim is to monitor the hot stamping process and enable early detection of changes in friction and wear which can be used for e.g. optimized maintenance and minimized scrap.

    The aim of this M.Sc. thesis was to improve the robustness of hot forming processes by studying the tribological behaviour of repair welded tool steel sliding against Al-Si coated UHSS under conditions relevant for hot stamping. Another aim was to obtain more predictable tool maintenance by the implementation of acoustic emission measurement system on a hot-strip tribometer and correlating condition monitoring signals to friction and wear phenomena.

    The tribological tests were carried out using a hot-strip tribometer in conditions representative of a hot stamping process of automotive components. Acoustic emission during sliding between hot work tool steel and different automotive component material surfaces was measured at room temperature in the same strip drawing tribometer and correlated to friction and wear of the surfaces to get more predictable maintenance intervals.

    Tool steel specimens were welded with the same material as the base material QRO90. Before conducting the tribological test, the repair welded tool steel pin cross-section was polished, etched, and observed under optical microscope and SEM to analyze the effect of Tungsten Inert Gas (TIG) welding process on the microstructure. The analysis was completed with EDS to study the elements in the microstructure. Microhardness was measured to obtain the microhardness profile from the repair welded tool steel pin surface to the bulk in order to study the effect of different microstructures on the mechanical properties. The weight and surface roughness of the pins were measured before the tribological test. After the test was finished, the weight of the pins was measured to calculate the weight difference. The sliding surface of the pins and the strips were photographed. The sliding surface of the pins was also observed and analyzed using SEM and EDS after the test to study wear characteristic of the repair welded tool steel at high temperatures.

    Acoustic emission signal from the sliding was studied using Toolox44 pins with surface roughness 300-400 nm and with lay direction parallel and perpendicular to sliding direction. Toolox44 pins were sliding against uncoated UHSS, as-delivered Al-Si coated UHSS, and heat-treated Al-Si coated UHSS strips. Acoustic emission was measured during the sliding at the same time as COF measurement. Weight of the pins was measured before and after the test and the wear damage on both surfaces was photographed. COF, AE signals in the time and frequency domain, and wear damage were compared and analyzed.

    It is found that repair welded tool steel has similar COF compared to the original hot work tool steel with the largest weight gain from the test at 700 ⁰C due to compaction galling mechanism with slower lump formation and the presence of wear particles, transfer layer, and formation of lumps. The weight gain is smaller from the test at 750 ⁰C due to faster lump formation. The weight loss from the test at 600 ⁰C is due to abrasive wear mechanism. SEM micrographs revealed that the repair welded tool steel surface and transfer layers can be found beneath a transfer layer. Wear particles adhered on the repair welded tool steel surface come from broken transfer layer or directly from Al-Si coated UHSS.

    A change in wear mechanism is indicated by acoustic emission burst signals or gradual amplitude change in the time domain. Frequency analysis of AE signals revealed a change in wear mechanism due to the formation of transferred material in the form of a lump causes AE signals with peaks at higher frequencies above 0.3 MHz to shorten.

  • Khan, Hiba
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    What Are the Security Challenges Concerning Maintenance Data in the Railway Industry2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Recently, technology advancement has brought improvement in all the sectors, including the railway sector. The Internet of Things (IoT) based railway systems have immense potential to improve quality and systems that will enable more efficient, environmental friendly railway system. Many research brought innovations that offer enormous benefits for rail travel. The current research focuses on the railway industries, as they want to reap the benefits of IT concept such as Cloud Computing, Information Security, and Internet of Things (IoT). Railway industries are generating a large volume of data every day from different sources. In addition, machine and human interactions are rapidly increasing along with the development of technologies. This data need to be properly gathered, analysed and shared in a way that it is safe from different types of cyberattacks and calamities. To overcome smart devices’ and Cloud’s limitations, the new paradigm known as Fog computing has appeared. In which an additional layer processes the data and sends the results to the Cloud. Despite numerous benefits of Fog, computing brings into IoT-based environments, privacy and security issues remain the main challenge for its implementation. Hence, the primary purpose of this research is to investigate the potential challenges, consequences, threats, vulnerabilities, and risk management of data security in the railway infrastructure in the context of eMaintenance.

  • Chen, Emily
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Thermal Loads in Space Turbines2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Prediction of thermal loads within cavities in space turbine, has as been a challenging task  in aspects of achieving accurate and reasonable estimations that are crucial for design concepts. The difficulty lies within the turbulent flow and its thermal interaction with the structure inside such section. It does not exist a method that works perfectly for prediction of thermal loads in any cavity and the taken approach to perform this kind of analysis has been differently chosen. The objectives of this work have been to improve methods for assessment of thermal loads in space turbines, especially calculation of the heat transfer coefficient and bulk temperature. As the thesis was conducted at GKN Aerospace Sweden, Trollhättan, one of theirs demonstrator turbine was chosen for the study case. Its first stage rotor blade and the nearby cavity were the main research regions. The flow can enter and exit the cavity through one slot and is characterized with a very low axial speed. For the studied regions, the wall surface has been subdivided into a number of segments. With prescribed wall temperatures and use of computational fluid dynamics (CFD) to compute the wall heat flux at the sections, the heat transfer coefficient and bulk temperatures were determined in three different ways. One of them was based on evaluating one single CFD result and derive the thermal loads from formulas. The others used by point-plotting approach, whereas one of them focused on formulating a model that describes the thermal interaction between the section walls. The results demonstrate that this model was able to predict a section's wall heat flux as a function of the wall temperatures in fair agreement with CFD results for a range of temperature variations. Further more, some of the predicted heat transfer coefficient at a section shows to be highly sensitive to the prescribed wall temperatures in the cavity and rotor blade.

  • Nordgren, Johan
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Beröringsskydd för elskena: Utveckling med användaren i centrum2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is the final assignment for a bachelor degree in Industrial Design Engineering via Luleå University of Technology. The project comprises 15hp and has been carried out in collaboration with MECON AB in Luleå, which works with construction, among other things. This report contains the development process of a touch guard for the power rails that runs along a traverse path. The task of the touch guard is to protect the staff at SSAB from risks that may arise if something falls on the power rails. Objects such as a wrench could create short circuits and be pushed off by the current in the electrical rails with high speed causing a hazard. The work is based on IDEO- the field guide to human-centered design, which is a human-centered process with three phases. In this case, the installer is the user. It is the installer who is affected by how easily mounted the touch guard is. Therefore, in order to design a user-friendly touch protection, an understanding of the user and its needs is required. By collecting information using interviews, observations, study visits and a literature study, a design specification could be created. This was then the basis for the remaining work that led to a bracket and three versions of the protection plates. Together with the users and the stakeholders, a final concept was chosen that fulfills the design specification. The report presents the process and its steps leading to a final concept. Later, the results are discussed and how well the work fulfilled the purpose and goals, and whether the work answered the research questions. 

  • Chapman, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Agneta, Larsson
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    HUMAN DIMENSIONS OF ENVIRONMENTAL CHANGE: Outdoor Human Environments: the changing face of climatic barriers to soft mobility and gathering in winter communities2018Conference paper (Other academic)
  • Sissakian, Varoujan
    et al.
    University of Kurdistan, Hewler, KRG, Iraq and Private Consultant Geologist, Erbil, Iraq.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Siting of Landfills for Hazardous Waste in Iraq from a Geological Perspective2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 295-311Article in journal (Refereed)
    Abstract [en]

    Iraq has been involved with two major wars in 1991 and 2003 (Gulf war I and II), which resulted in leaving large amounts of wrecked tanks, vehicles, weapons and ammunition. A considerable amount of the military waste contains depleted uranium (DU), which is a by-product of the enrichment of natural uranium for nuclear reactor-grade or nuclear weapons-grade uranium. DU used during the second Gulf war is more than 1100 to 2000 tons. This has serious effects on humans in Iraq and the environment. There is no national or international program for cleaning Iraq of DU wastes. To protect humans and the environment, three locations for disposals were suggested according to the geological conditions. These locations fulfill the requirements so that radioactive waste does not affect human life and the environment. To use these sites there should be proper design for the landfills so that it can perform for long period of time.

  • Nauzeer, Salim
    et al.
    Open University of Mauritius, MAURITIUS.
    Jaunky, Vishal Chandr
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Motivation and Academic Performance: A SEM Approach2019In: International Journal of Environmental and Science Education, ISSN 1306-3065, Vol. 14, no 1, p. 41-60Article in journal (Refereed)
    Abstract [en]

    Many models in educational have tried to clarify the causal relationships of motivation variables on student performance, by presenting hypothesized models, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) under structural equation modeling (SEM). Based on the literature, this model inspected the most robust stimuli of motivation: intrinsic, extrinsic, amotivation, self-efficacy and achievement motivation alongside with other variables like parental education, location, musculoskeletal pain (MSP), student body mass index (BMI), bag weights and tuition. SEM (unmodified and modified) is used to clarify the interrelationships of these variables and their relative contributions to academic performance. The sample consists of 324 students from Forest-Side State Secondary School (Boys). The results show that as predicted the latent variable motivation, mother education, private tuition and weights of bags have direct effects on students‘ performance using the modified standardized coefficients.

  • Roopchund, R.
    et al.
    Université des Mascareignes, Beau Bassin-Rose Hill, Mauritius.
    Ramesh, V.
    Reva University, Bengaluru, India.
    Jaunky, Vishal Chandr
    Université des Mascareignes, Beau Bassin-Rose Hill, Mauritius.
    Use of Social Media for Improving Student Engagement at Université des Mascareignes (UDM)2018In: Information Systems Design and Intelligent Applications: Proceedings of Fifth International Conference INDIA 2018 Volume 2 / [ed] Suresh Chandra Satapathy, Vikrant Bhateja, Radhakhrishna Somanah, Xin-She Yang, Roman Senkerik, Springer, 2018, Vol. 2Conference paper (Refereed)
    Abstract [en]

    The research responds to the global trend of using technology in higher education for improving student engagement and student satisfaction. The research ontology adopted is that students may benefit from a more interactive approach of learning in classes. The methodology used is the use of a pre-designed questionnaire to test the readiness of students and faculty members for the use of social media. Three components were extracted based on EFA which are namely social media as a facilitator, improving learning proficiency and trust in data security. The research outlines the benefits, risks and challenges for adopting SNSs for improving customer satisfaction and loyalty. It is important to note that social media tools are part of the Web 2.0 interactive and intelligent system of communication being used in different fields.

  • Ramesh, Vani
    et al.
    Bharathiar University.
    Jaunky, Vishal Chandr
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Oodit, Heemlesh Sigh
    Open University Mauritius.
    Perception Towards Adoption and Acceptance of E-Banking in Mauritius2019In: Proceedings of 10th International Conference on Digital Strategies for Organizational Success, SSRN - Elsevier , 2019Conference paper (Refereed)
    Abstract [en]

    This study aims at understanding the customer satisfaction on adoption of e-banking services at Mauritius. This is an empirical evidence, with the help of primary data (drop off survey) and secondary sources. The main objective of the study is to investigate in depth the customer's perception regarding e-banking adoption and their satisfaction. Also examines, if customers' choice of banks is influenced by the quality of e–banking services provided. For the purpose of the study, a well-structured questionnaire with 5-point Likert scale having 35 questions is used and personal details and customers' e-banking preference of Mauritians. The questionnaire was administered to about 250 respondents who are regular on online banking transactions, and the response rate is 74% (185 responded). More suitable and reliable statistical techniques are adopted, such as, ordered probit, ordered logit and descriptive statistics with the help software STATA. The 'confirmatory factor analysis' (CFA) approach is exploited to generate the results with the help of software SPSS AMOS (Analysis of Moment Structures). The original and modification indices of the model are evaluated with help of SEM, which further establishes the improvement in SEM`s effectiveness. It is evidence that, there is a relationship with different income group of respondents that the perception about the e–banking services offered by Mauritian banks. This study aims at contributing for the existing literature and assists for the policy makers.

  • Nauzeer, Salim
    et al.
    Open University of Mauritius, Moka, MAURITIUS.
    Jaunky, Vishal Chandr
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Ramesh, Vani
    REVA University Bangalore, INDIA.
    Efficiency Assessment of Secondary Schools in Mauritius: A DEA Approach2018In: International Journal of Environmental and Science Education, ISSN 1306-3065, Vol. 13, no 10, p. 865-880Article in journal (Refereed)
    Abstract [en]

    In the context of the quantitative approach to the evaluation of educational units there is an emerging interest in discerning the factors that affect the performance of a school. The data envelopment analysis (DEA) methodology provides an effective agenda for evaluating the efficiency of educational units, such as the secondary schools, in the presence of multiple inputs and outputs. In this paper we evaluate the performance of Mauritian colleges through DEA. The data deal with overall % passes at school certificate and higher school certificate in all secondary colleges for the year 2016. The 141 colleges are bunched on the foundation of factors such as school facilities and school population. The analysis results indicate that efficiency of colleges ranged between 0 and 1 with an average of 0.872(CRS) and 0.909(VRS) using Tobit model. The second stage analysis found that the location, zone, types of colleges, teacher-student ratio, student-class ratio, college status and canteen have significant effect on school’s performance.

  • Hamedi, Naser
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    On the deformation of fibrous suspensions2019In: Transactions of the Nordic Rheology Society, Nordic Rheology Society , 2019, Vol. 27Conference paper (Refereed)
    Abstract [en]

    An understanding of the rheology and dynamics of the deformation of fibrous suspension as a multiphase fluid is important in order to be able to fully disclose the flow behaviour from very low to very high shear rates. In this study, a flexible fibre model has been implemented in an open source Computational Fluid Dynamics code. The three-dimensional Navier-Stokes equations which describe the fluid motion are employed while the fibrous phase of the fluid is modeled as chains of fiber segments interacting with the fluid through viscous- and drag forces. The aim of this study is to investigate the fibre dynamics against several orbit classes - i.e. rigid, springy, flexible and complex rotation of the fibres1-3 enabling the model to have all degrees of freedom - translation, rotation, bending and twisting. The simulations are performed using the OpenFOAM open source software.

  • Yang, Ting
    et al.
    Dept. of Civil and Architectural Engineering, East China University of Technology, China.
    Weston, Richard
    Dept. of Production and Materials Engineering, Lund University, Sweden.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Time-Dependent Physical Interaction of Clay and Rock in HLW Repositories2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 273-293Article in journal (Refereed)
    Abstract [en]

    Disposal of canisters with Highly Radioactive Waste (HLW) in boreholes in crystalline rock can be made by use of “supercontainers” with waste and clay seals, moved down in clay mud which undergoes consolidation under the swelling pressure exerted by the dense clay seals. The concept can be used for disposal in mined repositories at a few hundred meters depth and in very deep boreholes (VDH) with saline, stagnant formational waters that are unlikely to rise to contaminate shallow groundwater. For disposal in mined repositories the supercontainers are suitably placed in 8-10m long inclined boreholes with 1,900mm diameter. The concept for disposal of HLW in the lower halves of 4 km deep holes relies primarily on the sealing capacity of engineered barriers, clay and concrete, in the upper halves of the holes. The parts of a VDH that are located in fracture-poor rock are sealed with dense, expandable clay, and by concrete cast where pre-grouted fracture zones are intersected. The deep holes will undergo convergence and eventually expose the clay, concrete and waste packages to radial compression. Using the Kelvin rheological model for predicting the radial convergence of the holes these components will be subject to a small pressure increase in the first 10,000 years. In a longer time perspective, they will be compressed by the slowly increasing confining pressure causing improved sealing ability of the clay.

  • Pusch, Roland
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kasbohm, Jörn
    Greifswald University, Germany .
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Hoang-Minh, Thao
    Greifswald University, Germany .
    Nguyen-Thanh, Lan
    Technical University of Darmstadt, Germany.
    Disposal of Low- and Intermediate-Level Radioactive Waste2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 237-272Article in journal (Refereed)
    Abstract [en]

    As for isolation of high-level radioactive waste by use of smectite clay it serves very well also for hindering radionuclides from low- and intermediate-level waste to contaminate groundwater. It can be used for minimizing groundwater flow through and along waste packages and for providing them with ductile embedment for eliminating the risk of damage caused by displacements in host rock or concrete vaults. The clay can have the form of liners placed and compacted on site over vaults constructed on the ground surface, or consist of compacted blocks of clay granules that are tightly placed around waste packages in underground drifts and rooms. In either case the initially incompletely water saturated clay will swell in conjunction with water uptake until tight contact with the confining medium has been established. The clay seals must be sufficiently dense to fulfill criteria set with respect to hydraulic conductivity and swelling capacity, paying due attention to the salt content in the porewater. Their physical and chemical stabilities must be acceptable in short- and long-term perspectives, which is a few hundred years for most low-level wastes up to tens of thousands of years for long-lived waste. 

  • Nakano, Masashi
    et al.
    Agriculture and Life Science, University of Tokyo, Japan .
    Yong, Raymond N.
    Geoenvironmental Engineering, Canada .
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mathematical Method Re-examined for Assessment of Ground Contaminated by Radioactive-Contaminated Groundwater2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 227-235Article in journal (Refereed)
    Abstract [en]

    In this paper we re-examined the transfer equation of radioactive substances in the ground and offer a more realistic transfer equation and other equations available for assessment of the ground contamination from radioactive-contaminated groundwater. The transfer equation takes into account kinematic and hydrodynamic considerations on mass conservation of mobile radioactive substances in a porous medium that typifies the ground. The other equations available for contamination assessment are concerned with deposition in contaminated areas and discharge flow of contaminants to the areas contiguous to contaminated area. The equations are derived on the understanding that disintegration of the radioactive substances adhering onto solids in the ground porous medium occurs as a sink term during the transfer of mobile radioactive substances. Finally, it is noted that the discharge of groundwater due to advective flow will be predominant in comparison to the discharge by diffusion

  • Pusch, Roland
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kasbohm, Jörn
    Greifswald University, Germany.
    Hoang-Minh, Thao
    Greifswald University, Germany.
    Nguyen-Thanh, Lan
    Technical University of Darmstadt, Germany.
    Mechanisms Involved in Maturation of Clay Seals in Boreholes for Storing Spent Reactor Fuel2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 197-226Article in journal (Refereed)
    Abstract [en]

    Smectite clay, especially montmorillonite, is proposed for isolating canisters containing highly radioactive waste (HLW) like spent reactor fuel placed in deep boreholes. It is used for minimizing groundwater flow around and along waste packages (“Buffer Clay”) and for providing them with ductile embedment for eliminating risk of canister damage caused by displacements in the host rock. The clay has the form of heavily compacted blocks of granules that swell in conjunction with water uptake until their full hydration potential has been utilized. The dense clay blocks are fitted in perforated supercontainers that are submerged in smectite mud. The long-term chemical stability of the clay is sufficient for providing the required waste-isolating capacity, which is primarily supplied by the heavyness of stagnant, very salt groundwater at depth.

  • Pusch, Roland
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kasbohm, Jörn
    Greifswald University, Greifswald, Germany.
    Hoang-Minh, Thao
    VNU University of Science, Vietnam National University, Hanoi, Vietnam .
    Degradation Mechanisms in Smectitic Clay for Isolating Radioactive Waste2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 115-130Article in journal (Refereed)
    Abstract [en]

    Most of the proposed techniques for chemical shielding of radioactive waste implies use of smectite clay, which degrades according to a well-known scheme. Since such “buffer” clay has to serve for many thousands of years, the mechanisms in the unavoidable long-term degradation process must be understood and accounted for as described in the paper. In addition to conversion of smectite to non-expandable minerals cementation by precipitation of siliceous matter created in the degradation process is of concern since it can reduce the self-sealing capacity of desiccated or mechanically damaged clay.

  • Pusch, Roland
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Popov, Viktor
    Ascend Technologies Ltd, Southampton, UK.
    Micro- and macroscopic ion diffusion controlled by clay micro-structure2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 99-114Article in journal (Refereed)
    Abstract [en]

    Very dense smectite clay surrounding canisters with high-level radioactive waste effectively stops migration of radionuclides due to flowing porewater, however, does not stop their movement by diffusion. The paper explains how the diffusion rate of released waste ions depends on the microstructural constitution referring to the mechanisms in diffusive transport and the sorption by the clay matrix of varying density. In general, diffusion refers to the transport of elements by action of random motions and works to eliminate distinct discontinuities in concentration. For smectite clay this process is complex since interlamellar diffusion is a 2-dimensional process on the microscale and takes place in diffuse electrical double-layers on the basal planes of the clay crystallites. This is in contrast with pore diffusion which is a 3-dimensional process. By making use of microstructural parameters one can distinguish the different contributions to bulk diffusion migration and create a basis for theoretical modelling of diffusive ion migration.  

  • Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Microstructure controls physical properties of smectite clay2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 63-98Article in journal (Refereed)
    Abstract [en]

    Environmental protection by isolation of radionuclides escaped from High-Level Radioactive Waste stored underground in crystalline rock can be achieved by surrounding the metal canisters by smectite clay, which provides hindrance of radionuclides to migrate into the surroundings, and ductile embedment of them for absorbing seismic and tectonic displacements in the host rock. The waste-isolating capacity of the expansive clay is explained by its high hydrophilic capacity and large specific surface area giving low porosity and limited interconnectivity of the voids, which both makes such clay low-permeable and gives it a very low through-diffusion rate of anionic species like iodine, and of some cationic radionuclides. The expandability of such clay means that it can swell and undergo self-healing in case of microstructural contraction caused by heating. The mechanisms involved in permeation and ion exchange are described based on conceptual microstructural models and their theoretical analogies. Stress/strain phenomena involved in saturation with fluids, desiccation, shearing under deviatoric conditions, and creep strain under stable conditions or at failure are described as well. Longevity matters, which have been richly treated in the literature, is given limited space. 

  • Popov, Viktor
    et al.
    Ascend Technologies, ac, UK.
    Adey, Robert
    Computational Mechanics Centre, Southampton, UK.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kasbohm, Jörn
    Greifswald University, Germany.
    Disposal of Radioactive Waste in Abandoned Mines2019In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, no 3, p. 1-38Article in journal (Refereed)
    Abstract [en]

    Countries using nuclear energy tend to favour disposal of Low-Level and Intermediate-Level radioactive waste in mined repositories consisting of series of tunnels or drifts connected to disposal tunnels at a few hundred meters depth. Abandoned mines can serve as repositories for such waste and the present study indicates that this would be possible also for High-Level Waste in the form of spent reactor fuel. The technique implies encapsulation of such waste in metal canisters surrounded by densely compacted smectite clay in relatively shallow mined repositories as well as in very deep bored holes. Intermediate-Level radioactive waste can be disposed of in caverns in the form of packages of metal containers cast in low-pH concrete and embedded in dense smectitic clay.

  • Acosta Laisequilla, Rafael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    3D Printed NovelZeolite 13X - Magnesium ChlorideComposites for Ammonia Storage2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today’s world regulations to reduce vehicle emissions are only gettingtougher, from said regulations the concept of a Selective Catalytic Reduction(SCR) unit was born, designed to provide a healthy dose of ammonia (NH3)to reduce the NOx compound into harmless components such as water andnitrogen. In this thesis novel approaches where investigated, by combiningthe fast physical absorption and desorption properties of a highly porous ma-terial such as zeolites with the high storage capacity of metal chlorides wecan potentially improve NH3 dosing in the low temperature operating range,such as when vehicles have just been turned on. Additive manufacturing pro-vides a faster and convenient processing route, that can cut down costs andallows for an inexpensive prototyping phase. With the aid of 3D printing weprepared a prototype cage-like shape using zeolite 13X with a combination ofPVP, binders and solvent,this structures would be used in conjunction withMgCl2, the latter would be enclosed the cage and so that their volume ex-pansion could be contained. This approach provides a low temperature rangefriendly solution for the release of NH3 in a SCR unit. The experimentationand characterization of the composites mixed by mechanical process showedgreat promise of what it can be achieved by incorporating zeolites and metalchlorides for ammonia storage and dosing. In the end a successful formulaand process to 3D print zeolite 13X using a PAM approach was deliveredthat showed similar results to untreated 13X.

  • Nyström, Louise
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Det förstärkta laglottsskyddet: Ett ytterligare skydd för bröstarvingars rätt till laglott2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med uppsatsen har varit att utreda varför det förstärkta laglottskyddet i 7 kap. 4§ Ärvdabalken kom till, vad bestämmelsen innebär och hur den tillämpas i praktiken. För att uppnå syftet har en rättsdogmatisk metod använts som innebär att man utreder gällande rätt utifrån rättskällorna såsom lagstiftning, förarbeten, rättspraxis och doktrin. I svensk rätt har en bröstarvinge alltid rätt till något som kallas för laglott vid fördelningen av kvarlåtenskapen efter sin förälders frånfälle. Laglotten är något som inte kan testamenteras bort av en arvlåtare. Det har därför förekommit fall där arvlåtaren istället gett bort delar av sin egendom för att på så sätt kunna styra fördelningen av sin kvarlåtenskap. Just därför tillkom det förstärkta laglottsskyddet, som utgör ett ytterligare skydd för bröstarvingars rätt till laglott genom att även innefatta gåvor som en arvlåtare bortgivit i ett syfte som kan likställas med testamente. Att syftet med gåvan kan likställas med testamente innebär att arvlåtaren ska ha haft samma syfte som med ett testamente, vilket är att ordna med sin arvsföljd före sin död. Ett testamente är gjort för dödsfall skull, vilket betyder att även gåvor som bortgivits för dödsfalls skull kan komma att återbäras på grund av det förstärkta laglottsskyddet.

  • Gren, Sanna
    Luleå University of Technology, Department of Arts, Communication and Education.
    Kunskap & bedömning i dansimprovisation: en intervjustudie om tre lärares perspektiv2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Studien beskriver och analyserar tre danslärares perspektiv på improvisation som ett ämne i dansundervisning. Syftet med stud

    I mitt arbete kommer jag att undersöka, beskriva och reflekteraöver mina egna kreativa processer i mitt eget skapande och iallmänhet. Genom intervjuer, tolkning av några av de låtar jaghar skrivit under året och med hjälp av loggbok så kommer jagatt jämföra och lyfta fram skillnader och likheter i min egen ochandras kreativa process/er.Genom att göra detta så hoppas jag på att få lära mig om hurandra jobbar och kanske hitta nya bättre sätt att locka framkreativiteten oftare och också på beställning.För att förenkla läsningen så vill jag förklara hur jag uppfattarföljande nyckelord.Inspiration; för mig handlar inspiration om var man hämtar sinaidéer och/eller vad som färgar ens idéer, det kan vara andraartister, det kanske kan vara fågelkvitter, en dikt, en film, nästanvad som helst.Kreativitet; är för mig skaparglädjen och självaskapandeprocessen.Co-write är när minst två låtskrivare skriver en låt ihop.Vidare så finns det ett väl använt begrepp; ”Mindfulness” somhandlar om att finna sig i ro och acceptans. Jag föredrarbegreppet mind-emptiness som för mig lite av en omtolkning av 1 2ordet mindfulness, där man fokuserar på att tömma sig själv. Förhur ska man kunna ta in någon inspiration om man redan självär full på tankar?

    ien är att öka förståelsen för hur lärare beskriver kunskaper i improvisationsämnet och vilka arbetsmetoder de har vid bedömning av dessa kunskaper. Tre danslärare från olika kontexter har intervjuats. Lärarna undervisar på olika typer av utbildningar och är specialister i olika dansgenrer. I studien tillämpas en kombination av ett sociokulturellt och ett kulturpsykologiskt perspektiv för att begreppsliggöra och analysera den information som samlats via semi-strukturerade intervjuer. En teoretisk modell för kulturell inramning används för att tydliggöra lärarnas kunskapssyner och bedömningsmetoder i improvisations undervisning. I studien framkommer dansimprovisation som ett medel för lärande av genrerelaterade kunskaper och som ett eget ämne innehållande kunskapsmål. Studiens resultat visar på att lärares kunskapssyn i improvisation kan relateras till en specifik genre eller till improvisation som ett eget ämne. När kunskaper i improvisation som ett ämne beskrivs kretsar dessa kring kompositorisk förståelse och konstnärliga attityder eller konstnärligt identitetsskapande. Danslärare använder sig, till största del, av formativ bedömning i den improvisatoriska undervisningen. Hur de formulerar feedback och skapar en gemensam förståelse med elever/studenter angående undervisningens mål har visat sig avgörande för att bedömningen ska vara formativ och bidra till lärande. 

  • Meulenberg, Vanessa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Multifunctional Wood Polymer Composites Reinforced with Graphene Nanoplatelets: Investigating if multifunctionality can be achieved in wood polymer composites through the addition of graphene nanoplatelets2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Graphene nanoplatelets (GNPs) were used to reinforce wood polymer composites (WPCs) in order to achieve multifunctionality. Multifunctionality could be achieved through the GNPs because of their excellent mechanical and electrical properties. The research consists of two parts: HDPE/GNP/WF composites and LLDPE/GNP composites. The HDPE part is a continuation of previous work. Here further mechanical characterisation was done (impact testing), impurities in the composites were identified, the manufacturing process that results in damaged wood particles was investigated and the Young's modulus of the composites were modeled. The impact strength was improved due to the addition of GNPs. WF composites exhibited more brittle behaviour and therefore a lower impact strength. The impurities were identified as some form of nanoclay introduced during the extrusion process. The particles were damaged during the extrusion processes. Little can be done about this as different shear configurations and/or screw speeds will result in a poor GNP dispersion and distribution. Modeling of the Young's modulus was the most accurate through applying the laminate analogy and rule of thumbs. The rule of mixtures does not represent the composites which have a preferred orientation. During the previous work done, it was found that the HDPE composite were not electrically conductive and therefore not multifunctional. The work was therefore continued with LLDPE and GNPs. LLDPE has more branches and is less dense, resulting in potential opportunities for the GNPs to form a network through the polymer. This could lead to a better conductivity. Mechanical and electrical characterisation was done of the LLDPE/GNP composites. Here multifunctionality could also not be achieved as the composites were highly electrically resistant. Mechanical testing indicated that the GNPs significantly enhance the LLDPE matrix. Here an increase of up to 170% could be seen in tensile modulus and an increase of 46% in tensile strength. Furthermore the GNPs improved the flexural properties and increase the resistance to viscoplastic deformation during residual strain testing. Overall the GNPs improve the mechanical properties significantly, but at 10wt.% GNP contents, multifunctionality could still not be achieved.

  • Mohamed, Mohamed Yousri Abdelmeguid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Spiral Groove Bearing Multiphysics Modeling2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cone crushers are widely used in the mining, mineral processing and quarrying segments of the industry to crush ores and large rocks. In such machinery, the load to be carried is rather heavy and the motion is gyratory which creates a need for a bearing set that can withstand such severe conditions. Sandvik AB is a high-technology Swedish engineering group specialized in tools and tooling systems for metal cutting, equipment, as well as tools and services for the mining and construction industries. One of their products relevant to the mining industry is the cone crusher which utilizes a 3-piece bearing set to carry thrust load. This bearing can be classified as a Spiral Groove Bearing \footnote{The abbreviation S.G.B will be used interchangeably throughout the thesis.}, and it has been incurred that it wears out rather quickly and is believed to be running under mixed-lubrication conditions where the interfaces in the bearing-set are not fully lubricated. The aim behind this thesis is to create a multiphysics model of this bearing in order to understand deeply how it works and the reasons why it does not perform as expected as well as to predict design improvements which can improve the performance of the bearing-set, thus increasing its operating life. It has been concluded that the bearing operates under severe mixed-lubrication conditions and that the generation of a squeeze film is the only method by which lubrication takes place due to the excessive depth of the grooves which is needed to allow for an adequate amount of cold oil to flow into the grooves and cool the interface as well as to accommodate for a considerable amount of wear particles. In light of the results and insight gathered from the simulations, possible design variations of the bearing which can be advantageous in terms of mitigating asperity friction in the interfaces of the bearing are discussed and tested.

  • Strid, Carl-Fabian
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    MAC-E-Filter characterization for PTOLEMY: a relic neutrino direct detection experiment2019Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    The cosmic neutrino background (CNB) can be composed of both active and hypothetical sterileneutrinos. At approximately one second after big bang, neutrinos decoupled from radiationand matter at a temperature of approximately one MeV. Neutrinos played an important role inthe origin and evolution of our universe and have been indirectly verified by cosmological dataon the BBN (Big Bang nucleosynthesis) of the Big Bang.It was Steven Weinberg in 1962 that first theorized on the direct detection of relic neutrinos.The signal of the relic neutrino capture on a tritium target can be observed by studying theendpoint of the electrons kinetic energy that are above the endpoint energy of the beta decayspectrum. The PTOLEMY project aims to archive direct detection of the relic neutrinobackground with a large tritium target of 100 gram, MAC-E-Filter, RF-tracking, Time of flighttracking and a cryogenic calorimetry.In this thesis the MAC-E-Filter have been simulated in two filter configurations. In the firstconfiguration, the electron were simulated five times in the filter. Two in the opposite sideof the detector, one in the middle, and two at the detector. In the second configuration theelectrons was simulated in the entrance solenoid at a fixed position of y = -0.19634954 m fromthe center of the filter and in random positions. Both multiple electrons and single electronswere simulated in the second configuration.In the single electron configuration the electron had a starting position of y = -0.19634954 mfrom the center of the filter, and an initial kinetic energy of 18.6 KeV. The first filter configurationsuccessfully accomplished to simulate the electron track, as the electron was reflectedback and forth between the entry and detector solenoid. The electric and magnetic field profilediered at the entry and detector solenoid. The second filter configuration successfully showedthat the electron will reach the end solenoid, when the filter length was 0.5 m. When the filterlength was increased to 0.7 m, then the electron was reflected in the middle of the filter. Thesimulation showed that the electron energy dropped below 1 eV from 18.6 KeV as the electronpropagated through the filter. The magnetic and electric fields decreased exponentially in thedirection of the detector solenoid. The Simulation of multiple electrons showed mixed resultsand would need more modifications in order to come to a final conclusion.

  • Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Poohphajai, Faksawat
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. innoReNew, Slovenia.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vikberg, Tommy
    RISE Research Institutes of Sweden, Skellefteå, Sweden.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Junge, Helmut
    ABiTEP GmbH, Berlin, Germany.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Application of GRAS Compounds for the Control of Mould Growth on Scots Pine Sapwood Surfaces: Multivariate Modelling of Mould Grade2019In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 10, no 9, article id 714Article in journal (Refereed)
    Abstract [en]

    Research Highlights: In this study, the Generally Recognised as Safe (GRAS) compounds were applied in order to study mould-fungi growth on dried Scots pine sapwood. Background and Objectives: The transition to the use of more sustainable wood-material may be possible by applying GRAS compounds that can control and prevent contamination by primary colonising mould fungi. Materials and Methods: Kiln-dried sawn timber was treated with three different GRAS compounds, and different fungal inoculation methods applied in order to investigate differences in the development of fungal communities. Results: Substances based on potassium silicate significantly reduced fungal growth and mould contamination on the studied wood surfaces. By combining wood-surface treatments with GRAS compounds, fungal-area size as predictors and mould grade as response, a partial least squares (PLS) model that makes it possible to predict mould grade on wood surfaces was developed. The PLS model is a key component in the development of a smart grading-systems equipped by e.g. high-speed digital cameras for the early detection of fungal attack on wood surfaces in different applications. However, the measurements based on chemical characterisation should be the next step to take in order significantly to enhance the model and increase the range of robust applications. In the current study, a multivariate model describing the influence of each fungal-covering area on mould grade was presented for the first time.

  • Kumari, Jaya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asset Management of Railway Tracks Using Stochastic Petri Nets2019Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Railways are one of the most important transport systems. It is crucial to have a rail network that is safe, reliable and available. Asset Management for railways involves the optimization of the maintenance activities based on asset condition, life cycle cost and availability of equipment. Irregularities in the track cause the wear of rail resulting in passenger discomfort, speed restrictions and line closures. The track is inspected for these irregularities and corrected using a tamping vehicle. The degradation behavior of the track can be modelled to predict the future degradation. This prediction forms the basis of the maintenance planning based on the expected track condition. A petri net model can be used to simulate the track degradation, inspection and maintenance process over a period of 20 years, and the outputs of the model are used for LCC analysis. Further, the cost is optimized with the safety risk to suggest maintenance threshold levels and Inspection Interval. The proposed methodology will assist the maintenance decision system for Asset Management of Railway track, which is strategic and cost effective. This methodology is demonstrated using a case study of a Line 414 in Sweden, by modelling the track behavior with Standard Deviation of Longitudinal Level. It can be further expanded and adapted for maintenance planning for similar assets within railways.

  • Jalili, Lemar
    Luleå University of Technology, Department of Arts, Communication and Education.
    Creative Processes2019Independent thesis Basic level (Higher Education Diploma (Fine Arts)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis is to understand what creativity is and how creative processes work in general as well as how different mindsets can influence it.

  • Nyberg, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Tjäldjupsberäkningar för järnvägsbank avsedd för höghastighetståg: Analys av tjälutbredning runt kulvertar2019Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [sv]

    För att förnya och förbättra den spårbundna trafiken inom Sverige är stambanor för höghastighetståg ett alternativ som utreds då det skulle innebära förkortade transporttider både för person- och godstrafik. Innan höghastighetsbanor kan etableras i Sverige finns det många faktorer som måste utredas. Eftersom tågen går med betydligt högre hastigheter än de tåg som redan används blir känsligheten för problem som kan uppstå i undergrunden betydligt högre och toleransen för sättningar och tjällyft är i princip lika med noll. På grund av klimatet som råder i Sverige finns det mycket att reda ut angående tjälproblematiken. Förutom låga temperaturer och vatten i jorden kan en trumma påverka hur tjälen utvecklas i järnvägsbanken. I den här studien analyseras påverkan som en trumma i järnvägsbanken har på tjälutvecklingen. Inverkan har analyserats utifrån ett tvärsnitt inuti järnvägsbanken för två olika köldmängder, -500 graddagar och -1300 graddagar. Innertemperaturen i trumman har antagits variera längs med trummans längd. Temperaturen har varierats inne i trumman att vara från 10 % upp till 75 % av köldmängden i uteluften. Förutom att analysera hur olika temperaturer påverkar tjälutvecklingen har den mängd material som behöver schaktas bort och ersättas med ett isoleringsmaterial för att förhindra att tjälproblem uppstår beräknats. Oberoende av trummans storlek och temperatur kommer trumman inte att kunna placeras direkt på terrassnivån utan att tjälfronten når det tjälfarliga materialet och risk för att tjälproblem ska uppstå. När temperaturen inne i trumman är 75% av köldmängden utomhus, och därmed nära temperaturen utomhus, blir tjälfronten även brantare än för lägre innertemperaturer. En brant tjälfront kan inducera större och mer ojämna tjällyft. För att undvika att problem uppstår måste ett isoleringslager av ett tjälpassivt material anläggas. Mängden material som måste ersättas ökar med trumdiameter och ökar betydligt beroende på om temperaturen inne i trumman är 10% eller 75% av utomhusköldmängden. Exempelvis ökar mängden under en trumma med 30 centimeters diameter från 1 m3 till 35,5 m3 respektive från 10,1 m3 till 58,4 m3 för en 150 centimeters diameter. Ökade mängder medför högre kostnader i både material och transporter, vilket är något som tillsammans med övriga faktorer senare måste analyseras vidare för att få mer kunskap och underlag inför en möjlig etablering av höghastighetsbanor.

  • Blomstrand, Greta
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Storskalig energilagring i elektrolysframställd vätgas2019Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
  • Edin, Erik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Ström, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Comparing a full scale test with FDS, FireFOAM, McCaffrey & Eurocode2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the rapidly growing field of CFD-calculations (Computational Fluid Dynamics), companies and organizations are bringing forth new tools, tools that display an image of a given fire scenario. These tools are developed because they provide time efficiency as well as a sustainable economic approach. Another useful tool is analytical solutions, these analytical solutions serve the same purpose as CFD-modeling, providing results of a given scenario. The purpose of this thesis was to simulate a fire plume with two different CFDprograms and compare the gas temperature from each simulation with a full-scale test. Also, analytical solutions were used to perform the same comparisons. Four different calculation models were utilized to obtain results. The CFD-programs were FDS (Fire Dynamics Simulator) and FireFOAM. The analytical solutions were performed using McCaffrey´s plume equation and Eurocode solutions for localized fire temperatures. FDS is a very well documented program, due to this, problems that arose were easily fixed. The structure of FDS enables the user to maneuver the program easily. SmokeView was used to visualize the simulation. FireFOAM is written in C++ and is operated through the command prompt. The structure of the program was time-consuming to understand mainly because of two reasons, primarily because the authors lack of knowledge in coding in C++, and second because of the LINUX environment. Moreover, the process of working in FireFOAM was mostly through trial and error. On some occasions, issues arose that could be solved by communication with other CFD users at CFD-Online. When major problems occurred, regarding the code or other CFD issues, Johan Anderson at RISE Research Institutes of Sweden guided us through most of these problems and enabled us to move forward with the work. ParaView was used to visualize the simulation, and Excel was used to evaluate the temperature data from the FDS- and FireFOAM simulations. For the calculations in FDS and FireFOAM, a sensitivity analysis was performed to see which grid size presented best results in each program. A grid size of 5 cm, 10 cm, and 20 cm were applied in FDS, and in FireFOAM the grid dimensions were set to 5 cm and 10 cm. The results showed that 5 cm was the most appropriate grid size for both programs. It would have been more favorably to simulate with several different grid sizes, to further strengthen the grid analysis. Though, due to the time frame of the thesis, further simulations were not performed. Calculations were repeated for the same scenario only with a lower HRR (Heat release rate). An extensive sensitivity analysis was conducted for FDS in the form of two different simulations. One simulation where HRR was the same as the full-scale test but with twice the area of the burner. In the second simulation, the same area was used on the burner as the fullscale test, but with half the HRR. Results from the analytical solutions were easy to achieve; however, the model has some limitations regarding calculations within the flame region. The estimated gas temperature, using FDS, aligns well with the full-scale test. The temperatures analyzed from FireFOAM deviated in general through the flame region and reached unreasonable high temperatures close to the ceiling. Since the analytical solutions were based on different conditions compared to those applied in the full-scale test, it was expected that the results should deviate. However, McCaffrey plume equations can still be used to give an approximate picture of scenarios similar to that of the full-scale test, and the same applies to Eurocode solutions for localized fire temperatures. Analysis of the results shows that FDS can be used to simulate similar scenarios. FireFOAM simulates a gas temperature that is overestimated within the flame region. One of the reasons for this was due to the grid size since the sensitivity analysis III showed that a refined grid size resulted in more correct temperature value, the reason for not simulating with a more refined grid size was due to the restricted time frame of this thesis. FireFOAM is, at present, recommended for researchers who wish to use the code for specific purposes. Therefore, given the same premises, FireFOAM is not recommended for the standard fire safety analysis.