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  • Norén, Hanna
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education.
    Sellin Nilsson, Emelia
    Luleå University of Technology, Department of Arts, Communication and Education.
    Genus i förskolan: Barns konstruktion av genus i den fria leken2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet i denna studie var att undersöka hur barn konstruerar genus i den fria leken på förskolan. Studien var av kvalitativ karaktär och utgick från ett socialkonstruktionistiskt perspektiv. Observation av barn i den fria leken var den valda metoden för datainsamling och denna registrerades med hjälp av observationsschema och ljudinspelning. Resultatet visade att barnens konstruktion av genus kom till uttryck i lekrollerna genom barnens olika sätt att använda kropp, röst, uttalanden och handlingar beroende på lekrollernas kön. Dessutom visade resultatet att genus konstruerades på olika sätt i barnens förhandlingar utifrån kläder, hårlängd, sättet att prata, användande av nikotin och vänlighet. Slutsatser vi dragit utifrån diskussionen av resultatet är att genus är föränderligt och att denna förändring sker i social interaktion mellan människor.

  • Näsman, Markus
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Evaluation of alternative methods forquality control of Tungsten Carbide: An evaluation of four different particle measuring techniques2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to evaluate four different measuring methods as potentialquality control tests for Tungsten Carbide (WC) raw material used in the hard metalmanufacturing at Seco Tools Fagersta. This was warranted as the current quality testcalled the HcK test, is very time consuming and the results provided that are used formilling time calculations cannot be relied on. The four measuring methods chosen wasLaser diffraction, X-Ray diffraction, Brunauer Emmett Teller analysis and Fisher Sub-Sieve Sizer measurement. These measuring techniques were chosen by Seco ToolsThe project followed the general structure of the project cycle modified to fit the projectand involving the steps project planning, present state analysis, goals and requirementdetermination, evaluation elimination of options and final of choice of option. Thealternative methods were evaluated using an evaluation matrix containing therequirements determined to be the most relevant for the quality control process. Therequirements were measurement precision, operator influence, ease of use, time requiredand operator time required. The ability of the measurement method to distinguishbetween all of the different WC powders used a Seco Tools was put as a must requirementas the new method is meant to serve as a verification test as well as a quality test.The analysis methods were evaluated practically through experiments and therefore atesting strategy was established. Initial test on two powder types was performed so thatan early evaluation could be done. During this stage both the Laser diffraction and the XRaydiffraction were eliminated due to poor results. The BET analysis and the Fisher Sub-Sieve Sizer performed better and was therefore tested further. Randomized testing wasthe method chosen when testing with all powders to minimize the environmental impacton the testing as this could affect the results of the study.The testing showed that only the Fisher SSS was able to distinguish between all thedifferent powders making it the only viable option as a new quality test. This was onlypossible when measuring on agglomerated material and the values extracted couldtherefore not be used further in the production. The Fisher SSS also performed the bestwhen ranked against the rest of the requirements, showing a high precision whenmeasuring on deagglomerated material and a combination of the two tests was thereforeconsidered.When compared to the HcK test the Fisher SSS showed a significant reduction in lead timebut also a reduction in information gathered and eventual defects controlled. The FisherSSS provides only an average particle size measurement and since no correlation has yetbeen established between the measured particle size and the required milling times it wasrecommended that the HcK test remains.It was recommended that a study is started aimed at establishing a correlation betweenthe measured particle size and the required milling time is started to investigate if this ispossible.

  • Olofsson, Emelie
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education.
    Hedman, Linda
    Luleå University of Technology, Department of Arts, Communication and Education.
    En förskola för alla?: Specialpedagogik-ett arbetssätt för att skapa en inkluderande förskola2019Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att bidra med kunskap om vad förskollärare anser vara viktigt i arbetet med barn i behov av särskilt stöd gällande deras egna förhållningssätt och planeringen av en inkluderande verksamhet. Vi har valt att utgå ifrån ett sociokulturellt perspektiv som fokuserar på lärande i samspel, kommunikation och att barnen är kompetenta individer. Kvalitativa intervjuer med två förskollärare genomfördes och bearbetades i tre steg: sortering, reducering och argumentation. Resultatet blev att förhållningssätt, samverkan, organisation, metoder och reflektion är viktiga aspekter gällande inkluderingen av barn i behov av särskilt stöd i förskolan. Diskussioner gällande vad begreppen inkludering och delaktighet innebär, har förts mellan oss studenter och även med förskollärarna i intervjuerna. De slutsatser som vi kunnat dra är att det specialpedagogiska arbetet är en viktig del av förskolans verksamhet och ska anpassas efter de individer som är i behov av detta arbetssätt. Samtidigt måste förskollärare ha i åtanke att specialpedagogik är ett arbetssätt som gynnar alla barn som vistas i förskolan. Med denna studie hoppas vi kunna belysa hur viktig specialpedagogiken är för en inkluderande förskola.

  • Stenberg, Anna
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Kommunicera mera!: Upplevelser av organisationsförändring ur ett medarbetarperspektiv2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When a workplace is in a process of change, there are several different factors that influence how employees among the organization react. This study was carried out at an authority that previously had a customer center that received incoming calls from customers but have now distributed the task to the authority's administrators. Thus, the duties of the administrators have changed, and this study therefore aims to examine the employees' experiences of the organizational change. To answer the purpose, three research questions have been enunciated; “how has the organizational change been communicated from management to employees?”, “how have the employees been involved in the change process?” and “what are the positive and negative experiences of the organizational change?”. This study is based on a qualitative method and the empirical material has been collected through eight semi-structured interviews with employees at one of the authority’s units. The theoretical framework has been divided into sub-categories such as communication, employee participation and co-workers attitudes and these has subsequently been constituted by Johansson & Heide (2008) and Angelöw (2010) theories about communication, Angelöw’s (2010) theory about participation, Angelöw’s (2010) theory about co-workers attitudes and Heide, Johansson and Simonsson’s (2012) interpretation of Bupp’s (1996) reaction curve regarding grief. Finally, Kotters (1996) 8-step model regarding change has been applied. The theoretical framework has been supplemented with scientific articles. The empirical data has been analyzed using theory and previous research.

    The study's results show that the experiences have been significantly negative as the employees felt that communication was inadequate. The strongest positive experience was when employees' views were received by management, resulting in a changed work schedule. Result of the study demonstrates that organizations advantageously should communicate the change purpose in order to create a greater understanding among the employees. Organizations should also involve the employees in an early stage in order to maintain a positive experience.

  • Trane, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    En studie i automatiska brandlarmsystem hos Norrbottens läns sjukhus2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Automatic fire alarm systems (AFAS) often play a central role regarding the fire protection in buildings. These systems are important in the sense that they are designed to detect fire at an early stage and activate certain safety systems to minimize the consequences of a fire. An example of this can be to activate the emergency alarm or specific control of the ventilation system. Hospitals are often complex buildings with multiple departments under the same roof, and because of this there are high requirements regarding the function and reliability of the AFAS.

    It is mentioned in Sweden, as well as internationally in Europe, that very few of the registered alarms from AFAS are due to actual fires, as compared to the number of alarms with no fire. It is not unusual that the percentage of actual fires are as low as 5% of all the registered alarms. Fires occurred in the hospitals of Norrbottens län are not only due to accidents and technical errors, but also the malice and desperate actions of individual people. So how does the AFAS in the five hospitals of Norrbottens län work, and what are the local fire departments conceptions of them?

    The AFAS in these hospitals were studied through a pilot study, document review and thereafter a qualitative interview study. The interview study was conducted with technical staff from hospitals, fire departments and inspectors. A primary focus was to determine whether these systems provides an equivalent protection across all the five hospitals or if any of the hospitals stand out in any way. The aim of this work has also been to investigate the opinions of the technical staff at the hospitals as well as the local fire departments. There are comprehensive regulations regarding which types of buildings that require AFAS, how they should be dimensioned, maintained and inspected. SBF 110 – Regler för brandlarm regulates that major inspections shall be performed yearly. The document review consisted of a compilation and comparison of protocols conducted each year at the different hospitals. Incident statistics from the fire departments were also examined.

    The incident reviews and protocols from the yearly inspections for the different hospitals differed. With a closer look, similarities between incident reviews and protocols could be seen. These similarities, along with gathered opinions from the interviews, showed that maintenance and actions taken to faults in the systems differed between the hospitals. Some for the better and some for the worse. The opinions of both the fire departments and the inspectors, independently, strengthen these observations. With these opinions along with theories and results from previous studies, conclusions could be made.

    The inspectors were of the opinion that some hospitals take actions and actively work for a safer and more reliable system, while others were perceived as if they are not as willing to make improvements. The fire departments also differed in their opinions. One said that the hospital is very large and not a major problem regarding alarms, but that a certain amount of alarms must be anticipated and accepted due to the large operation of a hospital. Another fire department said that their hospital is one of the largest contributors of the automatic fire alarms

    Abstract

    IV

    in the region and hope for an improvement. The technical staff in the hospitals were generally pleased with their systems and didn’t experience any major problems.

    By an overall assessment Gällivare hospital is considered to be the hospital that has the most amount of work to be done in order to be on the same level as the better performing hospitals. Contributing factors to this conclusion was the, by comparison, relatively high false alarm- statistics and low rate of actions taken to faults. The opinions of the inspectors did, as a third impartial part, serve as a good complement and reflected these observations. Kalix, Kiruna and Piteå were the hospitals with the least amount of perceived flaws. This conclusion was made from the high rate of actions taken to faults and the lower amount of false alarms generated by these hospitals. The local fire departments in these three places all had positive comments and thoughts regarding their local hospitals. The inspectors generally had good experiences with these hospitals as well.

  • Öberg, Oscar
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Lager & hantering av skivmaterial: Utvecklingsarbete hos Reklamcentra produktion2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes a bachelor program thesis in Technical design with orientation to production design carried out via Luleå University of Technology. The project has been performed at Reklamcentra Produktion Sverige AB and comprises 15 higher education credits.

    Reklamcentra produce and install exposure solutions, from simple stickers to more complex signage solutions, and are especially known for their LED-illuminated engraving- and paperflex signs. As a background to the project assignment, there is a potential order for 300 - 600 paperflex signs to be delivered within a four month time interval. An order of this magnitude entails new needs and conditions. The project is oriented towards production development and aims to map the production activities in order to determine needs and ultimately result in an action proposal.

     

    The five phases of the project have been defined as; Mapping & analysis, Requirement specification, Idea & concept development, Evaluation & selection and Detail processing. The implementation has followed a cyclical process where the phases have been worked through in turns with postponed focus for each turn. The survey started with a broad perspective to create a good information base on existing flows, working methods, and perceived problems within the production. The information collection is mainly obtained from interviews and observations of staff.

    Furthermore, the production process for the paperflex sign was examined more thoroughly. The sign consists of three different sheet materials which all undergo more or less extensive CNC machining and are then assembled with LED strip and detail components. Identified problems from mapping & analysis were strongly associated with the sheet materials storage units and handling. A requirement specification was drawn up containing the requirements that the conceptual solutions sought to solve and thereby established a foundation for idea development.

    In order to seek inspiration and experience regarding sheet materials in similar applications, a benchmarking was carried out at a glass wholesaler. Two potentially applicable and, in principle, different storage systems were examined in consultation with the supplier for the respective storage systems. A layout model that represented the existing production environment was established in SketchUp in order to be able to quickly implement and discuss different solution proposals. Idea and concept development resulted in three concepts that went further and were evaluated against an evaluation matrix inherited by the requirement specification. Winning concept from the evaluation were processed in detail where the sheet storage unit was dimensioned, and a mezzanine floor was introduced as a measure to provide a better order in the production environment.

     

    Final concept proposal is presented in different investment levels that can be implemented step by step. As a first measure, a new storage system is presented for arranging sheet materials and making them easily accessible and the introduction of the lean tool 5S. In order to meet the requirements specification to the greatest extent, it is recommended to install a Telfer - system with a vacuum yoke that can pick and place sheets from storage unit and on to CNC mill for machining.As a recommendation for continued work it is suggested to further investigate the telfer solution with constructor in order to ensure the realization of this principle.

  • Elenius, Lars
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Meeting between peoples: The Multicultural World Heritage of Gammelstad2019 (ed. 500)Book (Other academic)
    Abstract [en]

    The Sámi presence in Gammelstad and the lower river valley is reconstructed through court records, household strategies examinations and matrimonial records. As recently as the mid-19th century, many in the population could speak Sámi, Finnish or Swedish. We can also trace the collective memory regarding Sámi settlements in villages such as Rutvik, Alvik and Måttsund. There are place names there such as Lappgärdan as a topographical reminder of Sámi who lived there. The book also sheds new light on the early Finnish-speaking population in the coastal area. From the history of the 20th th century there are accounts of how Finnish war children in all haste had to leave Finland that was in the throes of a war with the Soviet Union. The first war children arrived in 1942 and were boarded out to families. Some of them remained even after the war.

  • Öberg, Maria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Sjöholm, Jennie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Undermarksplanering: Svensk praxis utifrån valda projekt2019Report (Other academic)
    Abstract [en]

    This study was carried out as part of the research project Sustainable use of the subsurface (2017–2019). The project aims to support the sustainable use of the underground space, and to clarify new possibilities for how underground matters can be integrated into urban planning.

    The purpose of this study was to investigate how planning processes for facilities and other underground operations are carried out in Sweden, how the interaction between planning above and below ground works, how underground information is handled in different types of projects, and indicate opportunities for improvement.

    The report is based on studies of a number of completed underground projects, where public planning documents have been examined and interviews with people who have had insight into the projects have been carried out. The study has identified a number of suggestions that could help improve the planning process for underground planning:

    Systematic and accessible information

    • Collect geoscientific information (including interpretations) from all underground projects in a common database.
    • Ensure that project owners and clients submit geoscientific information to such a common database.
    • The information should be archived and made searchable digitally with regard to confidential information.
    • The archives should be managed so that relevant material remains available for the appropriate length of time.

     

    Cooperation

    • Create a good collaboration climate early in the project, with relevant stakeholders.
    • Support harmonization of the application of regulations between municipalities.

     

    Strategic work

    • A coherent planning for land use above and below land at the various stages of the planning process.
    • Sub-regional resources in a regional perspective are highlighted in regional planning documents.
    • Managing target conflicts at an early stage by making them visible in both national and regional and local planning.
    • Ensure that the right level of information is developed for the various stages of the planning processes.
  • Jansson, Nils
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Allen, Rodney L.
    Volcanic Resources AB.
    Skogsmo, Göran
    Björka mineral AB.
    Vorbrodt, Nils
    Björka mineral AB.
    Bäckström, Mattias
    Björka mineral AB.
    An updated genetic model for metamorphosed and deformed, c. 1.89 Ga magnesian Zn-Pb-Ag skarn deposits, Sala area, Bergslagen, Sweden2019In: Proceedings of the 15th SGA Biennial Meeting, 27-30 August 2019, Glasgow, Scotland, Life with Ore Deposits on Earth, 2019, Vol. 1, p. 166-169Conference paper (Refereed)
    Abstract [en]

    This contribution presents an updated view on the genesis of stratabound Zn-Pb-Ag mineralization in the Sala area, Bergslagen, Sweden. Integrated legacy and new geological, geochemical and geophysical data reveal that the deposits are hosted by a complex array of magnesian skarn-altered zones in dolomitic marble. These mineralized zones parallel early faults and metavolcanic interbeds in the host marble, and converge downwards in the stratigraphy adjacent to a 1.89 Ga calc-alkaline granite-granodiorite batholith. Prograde alteration involved formation of early barren ferroan diopside- and forsterite-bearing skarns. Mineralization is mainly associated with subsequent alteration to tremolite, chlorite, serpentine, magnetite and calcite. The hydrous associations overlap mineralogically with assemblages formed during subsequent greenschist facies regional metamorphism between 1.87 Ga and 1.8 Ga. However, ferroan diopside and forsterite are unique to the alteration system, and indicate mineralization in conjunction with an early, high T, metasomatic alteration event at 1.89 Ga. The Sala deposits can be classified as Zn skarn deposits, albeit atypical in the magnesian nature of the skarns and the lack of minerals with essential Mn. The Fe and Mn content in magnesian silicates and carbonates is however sufficient to induce clear enrichment haloes of these elements around the deposits. The magnesian nature of the skarns probably reflect formation in a shallow marine continental backarc tectonic setting, and an importance of seawater in early pre-skarn alteration stages, such as dolomitization.

  • Elenius, Lars
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Möten mellan olika folk: den mångkulturella kyrkstaden i Gammelstad2019 (ed. 1)Book (Other academic)
    Abstract [sv]

    Genom domstolsprotokoll, husförhörslängder och giftermålslängder för att rekonstrueras den samiska närvaron i Gammelstad och den nedre älvdalen. Ännu i mitten av 1800-talet talade många i befolkningen samiska, finska eller svenska. Vi får också följa det kollektiva minnet efter samiska bosättningar i byar som Rutvik, Alvik och Måttsund. Där finns platser som kallas Lappgärdan som minnen i landskapet efter samer som bott där. I boken sätts också den tidiga finskspråkiga befolkningen i kustområdet i ny belysning. Från 1900-talets historia beskrivs hur finska krigsbarn tumultartat fick lämna ett Finland i fullt krig med Sovjetunionen. De första krigsbarnen anlände 1942 och utplacerades i familjer. En del av dem blev också kvar efter kriget.

  • Moulianitakis, Feidias
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Asimakopoulos, Konstantinos
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Benchmarking Framework for Transparent Data Encryption Systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the digital world of today, information is always at risk regardless of its state, at rest or in transit. Cryptography is the technology that promises to address the security issues that emerge. Hence, it was a reasonable consequence to introduce cryptography to databases. However, manually encrypting and decrypting data along with the key management is a burden for the regular user of a database. The need for removing this burden gave birth to Transparent Data Encryption (TDE).

     

    TDE technology is widely available nowadays and a number of vendors have developed their own solutions for protecting data at rest in a transparent way to the end user. However, cryptographic operations are resource intensive and introduce an overhead to the computational operations. The burden of cryptographic operations has drawn the interest of both academia and the industry for a long time before TDE appeared on the horizon. Hence, a lot of research has been done to measure the performance impact of those operations.

     

    Despite the extensive study for the performance of cryptographic algorithms, the performance of the TDE systems and the add-on computational burden for the introduced encryption has not yet been studied thoroughly. As a result, the current Thesis project tries to develop a theoretical benchmarking framework that evaluates the performance of Transparent Data Encryption systems. The study is conducted utilizing the Design Research methodology.

     

    The developed benchmarking framework focuses on the basic performance metrics of TDE systems, Elapsed time, CPU time and Hard Disk memory consumption. These metrics are calculated for varying key lengths, encryption algorithms and table sizes.  The framework follows a five - step procedure that includes the creation of topology - lab environment, creation of databases and definition of scenarios, activation of TDE feature, sequencial execution of scenarios and analysis of the results. The developed framework is evaluated by applying it on real TDE systems.

  • Islam, Raihan Ul
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Ruci, Xhesika
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Hossain, Mohammad Shahadat
    Department of Computer Science and Engineering, University of Chittagong, Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Kor, Ah-Lian
    School of Computing, Creative Technologies and Engineering Leeds Beckett University, Leeds, UK.
    Capacity Management of Hyperscale Data Centers Using Predictive Modelling2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 18, article id 3438Article in journal (Refereed)
    Abstract [en]

    Big Data applications have become increasingly popular with the emergence of cloud computing and the explosion of artificial intelligence. The increasing adoption of data-intensive machines and services is driving the need for more power to keep the data centers of the world running. It has become crucial for large IT companies to monitor the energy efficiency of their data-center facilities and to take actions on the optimization of these heavy electricity consumers. This paper proposes a Belief Rule-Based Expert System (BRBES)-based predictive model to predict the Power Usage Effectiveness (PUE) of a data center. The uniqueness of this model consists of the integration of a novel learning mechanism consisting of parameter and structure optimization by using BRBES-based adaptive Differential Evolution (BRBaDE), significantly improving the accuracy of PUE prediction. This model has been evaluated by using real-world data collected from a Facebook data center located in Luleå, Sweden. In addition, to prove the robustness of the predictive model, it has been compared with other machine learning techniques, such as an Artificial Neural Network (ANN) and an Adaptive Neuro Fuzzy Inference System (ANFIS), where it showed a better result. Further, due to the flexibility of the BRBES-based predictive model, it can be used to capture the nonlinear dependencies of many variables of a data center, allowing the prediction of PUE with much accuracy. Consequently, this plays an important role to make data centers more energy-efficient.

  • Almqvist, David
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Ett rättviseperspektiv på bodelning vid äktenskapsskillnad2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta examensarbete behandlas rättvisa inom bodelning inom ramen för den svenska äktenskapsbalken. Specifika frågeställningar är om bodelningen är rättvis utifrån filosoferna John Rawls och Robert Nozicks syn på rättvisa, men även lagstiftarens syn på rättvisa behandlas. Undersökningen visar att den svenska äktenskapsbalken uttrycker en mildare version av Rawls rättvisa. Rawls förespråkar en form av rättvisa där rättsstaten ska försöka utjämna olikheter mellan individer vid födsel men också ojämlikheter som kan uppstå under livets gång. Nozick förespråkar större frihet; alla ska oavsett klass, handikapp eller andra ojämlikheter, leva efter samma regler, även om detta leder till en sämre tillvaro för de som inte har samma förutsättningar. En av uppsatsens slutsatser är att Rawls hade uppskattat att den svenska bodelningen baseras på likadelningsprincipen – dvs. försöker utjämna egendomsförhållandena mellan makar vid äktenskapsskillnad – medan Nozick hade varit emot försöken att kontrollera individens fria val. Vilken syn på rättvisa lagstiftaren har utgått från för bodelning visade sig vara en svår fråga att svara på. I förarbetena till äktenskapsbalken diskuteras rättvisa betydligt mer, men inte heller här ges något konkret svar på lagstiftarens syn på rättvisa inom bodelning. Arbetet behandlar endast bodelning vid äktenskapsskillnad där båda makarna är vid liv och endast med utgångspunkt i två filosofers, Rawls och Nozicks, respektive uppfattning av rättvisa.

  • 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
  • Public defence: 2019-10-08 09:00 Auditorium A, Skellefteå
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Surface Densification of Solid Wood: Paving the Way Towards Industrial Implementation2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Surface densification of a piece of solid wood results in an increase in density and in hardness in the whole or a part of the densified material, and is one of the ways of improving the properties and value of low-density wood species. Despite efforts for many years, mass commercialisation of either bulk- or surface-densified wood products has not yet been achieved. Most of the previously tested densification methods have limitations in terms of processing speed and integration into the largely continuous wood processing chain, which leads to high production costs. Established methods to eliminate the set-recovery rely either on technologically complex close-system methods or on open-system methods that require relatively long periods of high energy input. For this reason, impregnation with adhesives is used in almost all commercially available densified wood products, and none of them have risen above their status of being niche products.

    Based on this background, three objectives for this project were formulated: (1) the development of a method for selecting the most suitable wood species for surface densification, (2) showing that surface densification can be carried out in a continuous manner at high process speeds, (3) and researching a fast open-system method to reduce the set- recovery.

    The method developed for selecting the most suitable wood species for surface densification was based on Lean principles, and it confirmed the suitability of previously studied wood species, such as Scots pine, spruce and poplar. In addition, several suitable alternatives from different parts of the world and from different types of forest were identified. This suggests a high potential for establishing such wood products on a global market level.

    Two studies using a continuous roller press showed that solid wood can be successfully surface-densified at process speeds of up to 80 m min-1, and that some defects, such as knots, are acceptable in the raw material, but the problem of set-recovery could not however be solved.

    A screening experiment testing different open-system approaches to reduce the set-recovery highlighted the potential of a novel method using ionic liquids as a plasticiser prior to the surface densification of solid Scots pine. The set-recovery could be reduced to 10%, with the time of high energy input being less than 10 minutes. The Brinell hardness was increased by a factor of 2.7 over that of undensified wood. A study with thermo-gravimetric analysis and digital image correlation showed that the set-recovery almost exclusively happens in the transition zone between the densified and undensified wood cells, where there is less penetration of the ionic liquids.

    The work accomplished in this project has successfully addressed several gaps in the field of wood densification, firstly, by employing a continuous surface densification process using a roller press, and secondly, by developing and studying a fast open-system pre-treatment with ionic liquids, which greatly reduces the set-recovery. Research will continue on a new band press, facilitating a swift transfer of knowledge between small- scale studies and the continuous surface densification of production-size wooden boards.

  • 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.