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  • 1.
    Adeva Rodil, Teresa
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Edge effect on abrasive wear mechanisms and wear resistance in WC-6wt.% Co hardmetals2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Wear of hardmetals is a complicated topic because the wear resistance and the wear mechanisms are influenced by microstructural factors. Although edge wear resistance has a vital importance, most of the researches made in laboratories are related to flat wear resistance using coarse abrasive paper. This situation produces problems with the prediction of abrasive wear behaviour and with the estimation of the lifetime of cutting edges of different kinds of tooling.

    Several studies have been done in order to clarify edge wear behaviour. It has been published correlations of the edge toughness to the load and to the bulk fracture toughness. In those publications coarse abrasive or Vickers indenter were used.

    In the present research, edge shaped specimens of WC-6wt%Co grades were investigated. In order to compare the obtained results for flat sliding and edge wear behaviour two test arrangements, pin on flat disc and edge on flat disc were employed. The specimens were tested using 120, 320, 800 and 2400 mesh SiC abrasive paper and the worn surfaces were investigated using SEM instrument to evaluate wear mechanisms. The edge wear was observed was discussed in relation to wear mechanisms investigated and correlated to the flat wear behaviour.

    The obtained results showed limited applicability of the results obtained with the pin on the flat disc test arrangement for prediction of the edge wear resistance, especially in the case when size of the abrasive particles is close to the WC grain size. However, both edge and flat wear results were similar in; 1) large WC grain sized hard metals wore more than fine grain sized against coarse abrasive paper whereas the reverse occurred against fine abrasives, and 2) wear mechanisms were mainly ploughing (or grooving) for fine grain sized hardmetals in all cases, whereas wear mechanisms changed from ploughing to binder removal and carbide pull-out going from coarse to fine abrasive paper.

  • 2.
    Aldaron, Mattias
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Anaerob rening vid StoraEnso Skoghalls Bruk2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An analysis of a specific application of anaerobic wastewater treatment at a pulp and board mill, Stora Enso Skoghall, was carried out. A literature study was done and effluent wastewater from CTMP pulp production was analyzed. The analysis consisted of a broad constituent analysis and an anaerobic treatment trial. Results from these test where used to calculate the treatment effectiveness and resulting energy potential at the mill.

    The literature study and constituent analysis showed that toxicity of the water to be treated, due to wood extractives and sulphur content, was of concern. Detoxification chemicals targeting these constituents where used in the anaerobic treatment trial. The trial consisted of a two chamber upflow reactor and aerobic post treatment. The result of the trial is that the water of concern has about 50% anaerobically degradable content. A full scale implementation of anaerobic wastewater treatment would result in a methane production of 3,76 to 7,76 GWh/yr. An application of anaerobic wastewater treatment will also result in electricity savings, in aerated pond, and increase the capacity margin on current sludge handling techniques.

  • 3.
    Almered Olsson, Gunilla
    et al.
    Norges Teknisk-Naturvitenskapelige Universitet, Trondheim, Norge.
    Bladh, GabrielKarlstad University, Division for Social Sciences.Månsson, BengtKarlstad University, Division for Engineering Sciences, Physics and Mathematics.Nyberg, LarsKarlstad University, Division for Environmental Sciences.
    Inte bara träd: hållbart mångbruk av skogslandskapet2004Collection (editor) (Refereed)
    Abstract [sv]

    Skogslandskapen - hur skall vi värdera dem? Ska de betraktas som rekreationsområden och kulturlandskap eller som arena för konflikter och dragkamp om olika resurser? Är skogsregionerna närande eller tärande? Vilka viktiga samband finns mellan skandinaviska och tropiska landskap?Detta är några av de teman som behandlas i denna spänannde bok om de många dimensionerna och resurserna som ryms i skogslandskapen. Boken ger nya och stimulerande aspekter på framtidsmöjligheterna för en hållbar utveckling för boreala skogslandskap. Den tar också upp det nödvändiga mångbruket av skogens resurser liksom den förändrade synen på människans roll i skogen. Och inte minst behandlas den ekologiska paradoxen att störningar behövs för att bevara skogens ekologiska mångfald.Boken är författad av samhällsvetare, miljöteknologer och ekologer inom den tvärvetenskapliga forskargruppen MiljöFocus vid Karlstads universitet.

  • 4.
    Andersson, Benneth
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Gustavsson, Stefan
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Förvaring och matning av bränslepellets: i en krävande miljö2007Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på Karlstads universitet på uppdrag av projektet Precer. På grund av sekretess kommer inte information om projektet att presenteras utan rapporten fokuserar på själva uppdraget. Uppgiften var att ta fram ett pelletförråd och analysera matning av bränslepellets med flexrör samt analysera olika pelletsorter. Detta pelletsystem kommer att appliceras i utomhusmiljö och utsättas för vibrationer och temperaturväxlingar. Angående pelletförrådet ges i denna rapport enbart rekommendationer till hur ett förråd skall konstrueras. Detta p.g.a förseningar i projektet. Arbetet inleddes med en förstudie bestående av en produktundersökning av de pelletförråd, matningssystem och pelletsorter som finns i nuläget. Förstudien gav oss referensramar till vad vi kunde rekommendera vid tillverkning av pelletförråd. För att undersöka hur pellets påverkas vid matning med flexrör utfördes tester på en testrigg. De tester som utfördes gick ut på att jämföra effektbehovet samt mängden finfraktion vid matning av två olika pelletsorter med två olika dimensioner på matarskruven. För att se hur flexskruven klarar att mata pellet vid vibrationer utfördes även ett skaktest. Det som framkom efter testerna var att det inte krävs mycket effekt för att driva flexskruven, att driva en tom skruv kräver endast 7 W. När det gällde bildning av finfraktion så är det i inloppet till matarskruven som det bildas mest. Det är även beroende på vilken pelletsort man använder sig av hur mycket finfraktion som bildas. Efter genomförda tester kan vi rekommendera att för ett helt jälvtömmande förråd skall det ha enbart ett utlopp till matarskruven. Alla väggar skall vara sluttande med en vinkel på minst 50° för att åstadkomma självfall. Påfyllning av förrådet skall orsaka så lite nötning som möjligt på pelleten. Inte tillverka tanken i material som skapar statisk elektricitet. Elektriska komponenter som installeras i förrådet måste vara ATEX klassade. Eftersom det inte är klart hur förrådet skall utformas när denna rapport skrivs ges inga rekommendationer till en specifik nivågivare utan behandlar tre möjliga, ultraljudsnivåmätare, kapacitiv nivåmätare och lastcell. För att minimera finfraktion föreslås norsk pellet vilken är den sort som har bäst hållfasthet men även står emot fukt bäst.

  • 5.
    Andersson, Christian
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Förbättring av utnyttjandegrad hos stansmaskin2008Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Bakgrunden till examensarbetet är att det finns ett behov av att höja utnyttjandegraden i stans- och lasermaskiner hos Lars Höglund AB. Anledningen till att utnyttjandegraden behöver höjas är att företaget vill bli mera lönsamt och mera konkurrenskraftigt.

    Uppgiften har varit att mäta utnyttjandegraden, göra en probleminventering och ta fram förslag på åtgärder som kan lösa de problem som kom fram i probleminventeringen.

    Vid probleminventeringen visade det sig att det går att höja utnyttjandegraden genom att bl.a. göra en ställtidsreducering, skapa ordning och reda, samt att förebygga flaskhalsar.

    5S är en metod som har använts för att ta fram förbättringsåtgärderna. Genom att följa denna metod, samt att göra några nya investeringar i företaget, ser det ut som att målet i detta arbete ska kunna uppnås.

  • 6.
    Andersson, Mattias
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Kylskåpsinredning: Praktiska funktioner2008Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
  • 7.
    Andersson, Robert
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Vattenhydraulik i vattenkraft2008Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    This report puts together the possibilities of water hydraulics. It also compare pros and cons of new adapted systems or when converting existing oil hydraulic systems to water hydraulics. A small comparison of environmental effects from oil and water treated for use in hydraulic systems will be made.

    A large question concerning water hydraulics is if it has the same durability as oil hydraulics. Another is if you get accelerated wear when you convert an oil hydraulic system to water hydraulics. For hydropower, Water hydraulics is already used for sluice gates. For the operating ring you need very high reliability but water hydraulics should be suiting for this application as well. Pitchcontrol for kaplanrunners is under development, at the moment the swivel on top of the turbineshaft is missing. If you want to convert a kaplanrunner you will also need to change the valves in the hub to get a good reliability.

    To be able to convert an oil hydraulic system you need to change some components: valves, filters and pumps, these needs to be adapted for water to have a reasonable lifetime. The lifetime is guaranteed to be 8000-10000h for a recently installed water hydraulics system. This is regarding to the pump, which is the part of both water- and oil- hydraulics with the shortest lifetime. If you compare water- with oil- hydraulics they have about the same lifetime. That has always been the goal for the supplier Danfoss development of water hydraulics.

    A water hydraulic system with pure tap water as pressure media will not affect the environment at all. Systems with monopropylen glycol and water as media will have only a small environmental influence. Monopropylen glycol that has leaked out will be broken down in 24h if it is taken care of in a cleaning plant. In the nature it will take slightly longer according to dowcal who produces the glycol. Monopropylen glycol has no cases of allergy reported, which makes the working environment and handling better than for hydraulic oil. Oil needs elevated temperature and the presence of earth to be able to break down, and still it takes considerable time.

    The lifetime on sliding bushings existing in the hydraulic cylinders for Älvkarleby hydropowerstation sluice gates have been investigated by laboratory work. Friction and wear was compared with hydraulic oil or monopropylen glycol with water (50/50). The contact was a sliding wheel against a sheet. These tests shows that the wear is equal if you test a composite against chromed steel, with the two different hydraulic medias. The friction was however lower when you tested it with monopropylen glycol and water as lubricant.

    In the case bronze against steel the results were the same. Monopropylen glycol with water gave lower friction, though the wear was equal between the two medias.

    The conclusion is that water hydraulics is a good alternative to oil hydraulics, thorough knowledge of the hydraulic components is necessary though. For instance if the materials in the system is suitable for use in water hydraulics, or needs to be changed.

  • 8.
    Andresén, Anja
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Matematik i förskolan: Hur arbetar man med matematik i förskolan?2006Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    The word mathematics is often associated to addition, subtraction, division or multiplication. This is not the kind of mathematics that belongs to pre-school. In my essay I have chosen to write about how mathematics is used in pre-school. In the literature it is written that the best way of becoming familiar with mathematics, is to integrate it in the every day life but that there are educators that use traditional mathematics education in pre-school. The questions I would like to answer are:

    1. How is mathematic used in pre-school?

    2. What are the educators’ opinions in pre-school regarding the introduction of the

    curriculum?

    In order to answer the questions I will use qualitative interviews. I have interviewed six pre-school teachers in two different schools in a middle sized town in Sweden. I have chosen six departments in order to get two educators’ views on three types of children groups, infants, siblings and an integrated group.

    The answers showed that the level of using specific mathematics education is very low. Instead mathematics is integrated with everyday life situations such as when laying the table or portioning food.

    The investigation also showed that all persons interviewed expressed a positive attitude towards the implementation of the curriculum for several reasons. The addition has given them a sense of acknowledgement in their earlier work, given their jobs a higher status and also strengthened and broadened their view on mathematics in pre-school.

  • 9.
    Banell, Mia
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Björfelt, Ulf
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Svetspåverkan på martensit-austenitiskt rostfritt stål2007Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This thesis is performed at Rolls-Royce AB in Kristinehamn. Rolls-Royce AB is a world leading supplier of different transmission systems for example ship propellers.

    This report contains a material investigation in martensitic-austenitic stainless steel SS EN GX4CrNi13-4 which is used in their propellers.

    The propeller blade is sand casted and cavities that may form during casting are fixed by weld repairing. The aim of the project work was to look into what effects the welding has on the material considering the tensile strength, microstructure and hardness (some parts of a WPS, Welding Procedure Specification)

    Different stress-relieving annealing temperatures have been tested after welding to study possible influences.

    According to the results and analysis the conclusions are that weld repairs and stress-relieving annealing does not affect the properties negative considering the tensile strength, microstructure and hardness.

  • 10.
    Barza, Sorina
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Persson, Lars-Erik
    Department of Mathematics, Luleå University.
    Soria, Javier
    Department of Applied Mathematics and Analysis, University of Barcelona, Spain.
    Multidimensional rearrangement and Lorentz spaces2004In: Acta Mathematica Hungarica, ISSN 0236-5294, E-ISSN 1588-2632, Vol. 104, no 3, 203-224 p.Article in journal (Refereed)
    Abstract [en]

    We define a multidimensional rearrangement, which is related to classical inequalities for functions that are monotone in each variable. We prove the main measure theoretical results of the new theory and characterize the functional properties of the associated weighted Lorentz spaces.

  • 11.
    Bergman, Ivar
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Baire category theorem2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis we give an exposition of the notion of category and the Baire category theorem as a set theoretical method for proving existence. The category method was introduced by René Baire to describe the functions that can be represented by a limit of a sequence of continuous real functions. Baire used the term functions of the first class to denote these functions.

    The usage of the Baire category theorem and the category method will be illustrated by some of its numerous applications in real and functional analysis. Since the usefulness, and generality, of the category method becomes fully apparent in Banach spaces, the applications provided have been restricted to these spaces.

    To some extent, basic concepts of metric topology will be revised, as the Baire category theorem is formulated and proved by these concepts. In addition to the Baire category theorem, we will give proof of equivalence between different versions of the theorem.

    Explicit examples, of first class functions will be presented, and we shall state a theorem, due to Baire, providing a necessary condition on the set of points of continuity for any function of the first class.

     

  • 12.
    Björnvall, Patrik
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Ersättningsmaterial till stellit 6 & 122004Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This report contains a degree project made by Patrik Björnvall, student in material science in the division for Engineering Sciences, Physics and Mathematics at Karlstad University. The report is made in spring semester 2004. The report is a continuation of the work made by Jonas Gylling and Niklas Berglund made for SOMAS spring 2003.The project was made in a co-operation with SOMAS Instruments. They manufacture butterfly valves etc. At present the spindle is made of SS 2390-95 and laser coated with Stellite 12 and the bearing is centrifugal casted in Stellite 6. Stellite is a commercial name of cobalt based alloys from Deloro Stellite Ltd. The valves work at 350-550°C, the pressure varies between 15-35 bar. Demands from the costumers will increase the temperature to 630°C and the pressure to 45 bar. This is to get higher efficiency. The demands on the valves is to have a lifetime without stop for at least 12 years. AB SOMAS Instruments are not sure if their materials will fit the new demands.The purpose of this project is to find a material combination and eventually a new design that will live up to the new demands. Only the bearing is allowed to change shape, so that the remaining parts can be used.The first step in my report was to make a literature study to find suitable materials. I also used FEM-calculations to find out the magnitude of the loads on the bearings. Totally six different calculations. Five of them had different curvated surfaces, to find out which one gives the lowest contact pressure.The result was evaluated and six different materials were coshen with cobalt, nickel and iron base. Some of them were reinforced with NbC or TiN. One used valve of model VSS PN 50 DN-500 was analysed to get knowledge about the wear mechanism. The wear rate is higher at the beginning and at the end of the bearing. The wear test was according to the block on cylinder method, to find out the wear rate for the different material combinations. Stellite 6 was first tested as a reference test with temperature and pressure which are in use today. The result was compared with the other materials with higher temperature and pressure. The number of tested combinations was 3 cylinders and 15 blocks.The wear rate was compared by weight loss from the block, analyses on the wear surface in SEM and the microstructure in crosssection of the material. The wear mechanisms in the reference test were booth adhesive and abrasive wear. For the rest of the tests in full pressure and temperature the adhesive mechanism dominated. Duroc F25 + NbC had the lowest wear rate but the surface carbide had a severe oxidation.  Stellite 712 was the best candidate for the cobalt based alloys. The wear rate for Stellite 6 increased four times with full pressure and temperature, and it is not recommended as a future bearing material. The best bearing material is Stellite 712 and Stellite 12 for the spindle. A future research about the hard phase particles could optimise the material selection even more.

  • 13.
    Björström, Cecilia
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Morphology studies of thin films of polyfluorene: fullerene blends2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The formation of thin films of polymer blends by spin-coating from solution is characterised by rapid solvent quenching, a process that results in non-equilibrium morphologies. Thin films of conjugated polymer blends are used as the active material in polymer solar cells, in which the morphology may have drastic effects on device performance.

    In this thesis results from morphology studies are presented for spin-coated thin films of polyfluorenes and co-polymers of polyfluorene blended with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The surface morphology was investigated by atomic force microscopy (AFM) and was found to depend on the blend ratio as well as the chemical structure of the blend components. The spin speed, which determines the thickness of the spin-coated thin films, was also found to influence the morphology. Secondary ion mass spectrometry (SIMS) was used for depth profiling of the chemical composition in thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4´,7´-di-2-thienyl-2´,1´,3´-benzothiadiazole)] (LBPF5) blended with PCBM. The films were found to be vertically phase separated with a four-fold multilayered structure.

  • 14.
    Borck, Andreas
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Logistisk översikt: Sandvik CalamoIndependent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [sv]

    Examensarbete vid maskiningenjörsprogrammet 2005. Uppgiften behandlar intern logistik hos företaget Sandvik Calamo i Molkom. Företaget är ett förädlande företag som elektropolerar rostfria syrafasta rör. Utbudet av olika rörtyper och dimensioner är stort och fabrikens produktion kräver stor flexibilitet. Fabrikens layout (dvs. maskinplacering) är dock gammal och lokalen har för liten area. Förbättrad logistik kan fås genom förändring av utrustning samt dess placering vilket har undersökts i detta arbete. Dels har utrustningen undersökts och idéer för bättre och mer flexibel utrustning tagits fram dels har layouten analyserats. Slutresultatet är att en klar förbättring går att nå med hjälp av mycket små medel. Endast mindre ombyggnationer behövs för att förbättra flödet av gods. Teoretiskt går att räkna med cirka 4 % förbättring, men den verkliga förbättringen blir nog större, då även förbättrad arbetsmiljö räknas in.

  • 15.
    Brunbäck, Jonatan
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Niklasson, Aron
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
     Utredning av problem vid deponigasutvinning:  Vid Östby miljöstation2010Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Landfill gas has been extracted at Östby landfill site north of Åmål Sweden since 2003. During the last three months the extraction rate has experienced a reduction. The organic carbon in the waste will degrade over time in an anaerobic environment and landfill gas is emitted as a result of this process. Landfill gas has an environmental impact in the forms of foul odour, fire hazard and contributes to global warming. This gas must be processed in some way to limit the environmental impact. Östby landfill site has a gas collection system containing gas wells made from perforated steel tubes that is used to extract the gas from the site. The gas which contains methane is combusted in an engine attached to a generator which delivers electricity. The main concern, environmental impacts aside, is the recent reduction of gas extracted from the wells and this impacts the production of electricity. The total gas flow from the site decreased by 25 percent during the last seven months.

    The purpose of this study is to identify what factors impacts the landfill gas extraction at Östby landfill site. Suggestions of potential solutions to these problems will also by central in this report. An evaluation of the gas extration rate has been done to determine if it can be improved. The goals are to increase gas extraction rates which will give lower environmental impact and a higher power production at Östby landfill site.

    The method in this report has been divided into two sections. The first section entails the construction of a theoretical model to obtain an indication of the potential gas production in the landfill. The statistical history of the landfill sites gas extraction has been examined to act as a foundation for the theoretical model. Model is used to establish how much gas should be generated at this time. The second part examines possible technical problems with equipment. Water levels in the wells and the landfill has been studied to indicate how much perforated area that is available for gas extraction. A device to push compressed gas backwards through the well has been installed. This will help to show signs of depressions in the pipelines from the wells to the gas station as well as problems with low permeability. Depressions in the pipes will collect water condensate from the landfill gas thus decreasing the gas flow..

    The results indicate that the gas production in the landfill is not the source of the reduction of landfill gas. The water level assessment showed that some wells are completely submerged in water. The system for pushing compressed gas gave a preliminary indication of which wells suffer from water condensation or low permeability problems.

    The theoretical estimate of the gas production is 3.5 to 4.5 MW. This means that the current production is not a limiting factor for the gas extraction system. Identified problems are high water levels, depressions in pipelines and low permeability. Compressed air should be driven through each well on a regular basis to get a better estimate of which wells have problems due to condensation.

  • 16.
    Cano, Cédric
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Integrering av ett främmande språk i matematikundervisningen2009Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Content and Language Integrated Learning (CLIL) is a relatively new method for learning a foreign language. CLIL programs are growing in popularity and more and more schools are adopting it all around the world. There is still no special education for the teachers working with CLIL, though research suggests it may be an effective method for achieving good results.To get a realistic view of the work of a CLIL teacher, I have interviewed four different mathematic teachers who work at CLIL international schools in Spain with English as the foreign language. I have compared their methods and experiences with the main ideas of current research in this particular field.The survey shows that the teachers’ views about how CLIL is to be used do not completely correspond to that of the research. My conclusion is therefore that training in CLIL is needed.

  • 17.
    Christensen, Dan
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Prefabricerade eller platsbyggda tak: En jämförelse med avseende på ekonomi, arbetsmiljö och kvalité2007Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The main purpose with this diploma work is to compare the two production methods, premanufacturing and on-site construction. The goal is to deduce if one of the alternatives is more attractive than the other in view of economy, work environment and quality. To gather information about how the construction works, two various construction sites have been studied. The premanufactured roof was studied in Kristinehamn during the construction of an eventhall and for the on-site construction a sport arena in Årjäng. Information was also gathered through a literature study and by interviewing active persons in the building industry.

    The premanufactured roofs have been used in Norway with great success during a long period of time but are not that common here in Sweden. By increasing the understanding of the advantage and disadvantage of premanufactured building elements, they can be used with greater success. The building industry has under some time been pushed to build cheaper and faster, maybe the premanufactured element is the way to achieve this goal.

  • 18.
    Denelin, Thomas
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Eriksson, Martin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Energideklarationsutformning2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    This report is about designing an energy declaration for constructions in Sweden. The declaration have been used for two houses. Acording to EU:s directive about energy declarations buildings that is going to be restored, sold or built shall go though a control by an energy expert. This is to get a document that shows how good or bad the construction is according to energy point of view.

    The law regarding these declarations will start apply 1st of October according the goverment. Transaction of these rules are suggested, specialbuildings and residens have to be declarated at the end of 2008. Remaining buildings have to be declarated from 1st of January 2009. The declarations in this report is done on a detached house that is located in the municipalty of Torsby and a flat house that is located in central of Karlstad.

    This is quite new and it has not been decided guiding principle of the design for the energy declaration. Boverket and the goverment got some suggestitions of this that should be included. To calculate the energy consume on the objects the program Enorm 1000 have been used. The declarations are based on energy that is consumed; this will be compared with a reference value. Measures is proposed to improve energy saving.

    The need of energy for the detached house is 124 kWh/m² and has 2 kWh/m² less consume than the reference house. The recommended measure did make the consume drop down to 92 kWh/m².

    The need of energy for the flat house is 102 kWh/m² and has 20 kWh/m² less consume than the reference house. The recommended measure did make the consume drop down to 97 kWh/m².

  • 19.
    Eid, Josef
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Svensson, Sebastian
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Woodstar Extreme: Racerbil för rörelsehindrade2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    This report was written in the spring 2005 at Karlstad University by Josef Eid and Sebastian Svensson. The report contains their examination work (15 points) which was the final course in their education, Bachelor of Science in Innovation and Design Engineering. The assigner for this project was the company Woodstar AB. Tommy Andersson was their contact at Woodstar and Lennart Wihk was their examiner at the university.

    Woodstar manufactures vehicles adjustable for disabled persons. The Company was in the final stages in developing their Woodstar Extreme, which is a new racing car for tracks. Woodstar Extreme has the purpose to fulfil a need and to carry out the dream that people can practise motor sport on the same conditions, irrespective of disabilities.

    The main task for this project was to design a body for the Woodstar Extreme. The students designed a concept which implied a single body covering the racer with a separate cover in the back. The body can be lifted off in one part when needed, for example when a disabled person gets in or out of the car. The cover in the back can be lifted off separate or together whit the whole body. The body will be light due to the glass fibre construction that will be used. The semantic demands of a classic sport car with a unique look were accomplished. The design’s aerodynamic features, with air inlet in the front and on the sides and air outlet in the back, have been approved. The racing car was presented with a digital model and animation and a plastic model.

    Josef and Sebastian also manufactured the dummy for the body, which Woodstar will use to make the glass fibre bodies of. Until the body is concluded the students will act as advisors and assistants for Woodstar.

    The presentation of the project went well but the exhibition was a bit mediocre. The manufacturing of the dummy took longer time then planed, due to the unnecessary polishing of dummy. The students took to much work on them selves (have been enough with a conceptual design of product), but due to their engagement they created their own conditions. During this project they had a lot of fun and learned many grateful things. Both students and the company had a great cooperation in this genuine and well made project.

  • 20.
    Ekberg, Joakim
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Geometries of Binary Constant Weight Codes2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    This thesis shows how certain classes of binary constant weight codes can be represented geometrically using linear structures in Euclidean space. The geometric treatment is concerned mostly with codes with minimum distance 2(w - 1), that is, where any two codewords coincide in at most one entry; an algebraic generalization of parts of the theory also applies to some codes without this property. The presented theorems lead to a total of 18 improvements of the table of lower bounds on A(n,d,w) maintained by E. M. Rains and N. J. A. Sloane. Additional improvements have been made by finding new lexicographic codes.

  • 21.
    Eklund, Per
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Klarar elever att lösa icke rutinmässiga uppgifter i matematik?2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The purpose of the paper is to examine how students are capable of solving problems that can not be solved routinely and where they do not have access to facilities. In addition, I want to examine how the student's grades and number of Mathematic courses pupils have read affect the result. In order to get the answers I let students in two classes from the natural sciences programme, one from grade one and one from grades three, respond to a questionnaire consisting of problems that can not be solved routinely.

    The result shows that students in grade three passed the exam clearly better than students in grade one did, and in both classes’ students with higher grades performed better than students with lower grades. The most surprising was that both classes despite high grades in Mathematic revealed some shortcomings in number sense.

  • 22.
    Eklund, Per
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    P-adiska tal2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    De p-adiska talen vars främsta användningsområde ligger inom talteorin beskrevs först av den tyske matematikern Kurt Hensel 1897.

    För varje primtal p, så utvidgas talsystemet Q av rationella tal till ett större talsystem som betecknas Qp, de så kallade p-adiska talen.

    En annorlunda valuation av rationella tal ger ett så kallat icke-arkimediskt absolutbelopp samt en annan metrik än den vi är vana vid, en ultrametrik. Vilket gör att kroppen av p-adiska tal Qp får en annorlunda topologi.

    Ett icke-arkimediskt absolutbelopp har samma egenskaper som ett vanligt arkimediskt absolutbelopp, samt en extra egenskap nämligen .

    Avslutningsvis använder vi oss av Hensels lemma, vilken bygger på Newton-Raphsons metoden för att lösa ekvationer, för att bestämma om ett polynom har rötter i Zp och i så fall vilka de är. Då den p-adiska analysen på många sätt är lättare än den reella analysen så visar Hensels lemma ganska lätt om ett polynomen har rötter i Zp.

  • 23.
    Ekström, Jona
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Trigonometric series with monotone coefficients2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    This work is devoted to trigonometric series with monotone coefficients. The main problem is to study conditions under which a given series is the Fourier series of an integrable (or continuous) function.

  • 24.
    Elofsson, Andreas
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Hallin, Mikael
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Självkompakterande betong: Ytjämnhet utan efterbehandling2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    Concrete moulding is a heavy moment in the building process and for a long time contractors have used an admixture to create a concrete that is easier to handle. However many hours of work and heavy moments has been required. After laser levelling, vibrating, screeding and troweling a surface that is almost flat has been obtained. Yet not flat enough to eliminate floor levelling and thereby avoiding bending parquet flooring or curved plastic flooring.

    Self-compacting concrete (SCC), or vibrating free concrete as it was named in the beginning, was developed in the eighties in Japan and showed up in Sweden in the late nineties. It is a concrete that contains an admixture and filler that together makes the concrete flow under its own weight, completely filling the formwork and achieving full compaction, even in the presence of congested reinforcement. SCC is approximately 10-15 % more expensive than traditional concrete but is motivated with faster construction times, fewer workers and an improved work environment.

    Since SCC just about flows the resulting surface becomes almost perfect. Experience shows that surfaces are nearly perfect after laser levelling, screeding and dry smoothing. Despite the advantages of the flat surfaces and the established improvement on the work environment, AB Färdig Betong in Karlstad, Sweden has only delivered SCC to eight projects since 1997.

    The aim of this degree thesis is to determine if SCC can be motivated based on the flat surfaces that can be obtained after moulding compared to traditional concrete.

    The degree thesis has been performed in cooperation with Skanska Sverige AB in Karlstad, Sweden at their two projects with SCC in spring 2006. The measurement of SCC surfaces was made in Färjestad, Karlstad and reference measurements of traditional concrete was made in Karlstad and surroundings. The measurement have been complemented with interviews that present experience of producing, delivering, receiving, moulding and after treating SCC.

    The requirements for on site moulding concrete surfaces that are to be followed are found in Hus AMA 98 and is defined as curve, rake and level variance. The result from the measurements are judged on the basis of the requirements.

    Conclusions

    Correctly performed SCC can create a surface that fulfils the requirements in Hus AMA 98 for a class B floor.

    The use of SCC in larger housing constructions makes conditions for a lower total cost. This is based principally on fewer workers, faster construction times and less after treatment of the moulded surfaces.

    The confirmed possibilities of improved surfaces after moulding should mean that more contractors will use SCC in the future.

  • 25.
    Elvsén, Johanna
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Föräldrar och förskolans matematik: En enkätundersökning om föräldrars inställning och uppfattning om matematik på förskolan2006Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    According to the curriculum, Lpfö-98, pre-school shall work with developing the children’s ability to discover and use mathematics in meaningful contexts. I think that a prerequisite for a good pre-school activity is that you have the parents support and interest in the activities that occur. Therefore, through a questionnaire, I have examined how parents relate to mathematics in pre-school, what their attitudes are and their thoughts about what form it should take. This has been compared to the pre-school’s thoughts about mathematics in their activities, which they have shared with me through interviews.

    Mathematics in pre-school is often seen as something positive as long as it is under playful forms, but at the same time there are many other activity areas that are of higher priority according to pre-school parents. There are also parent groups who think that mathematics belongs in school and that the time spent in pre-school should be used differently.

    Parents have a certain attitude towards how and which form of mathematics that should occur in pre-school. Often, they believe that it should be introduced through playing and that it can be a part of the children’s spontaneous games, rhymes, jingles, movements and other activities.

  • 26.
    Ericsson, Leif
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Silicon/Germanium Molecular Beam Epitaxy2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Molecular Beam Epitaxy (MBE) is a well-established method to grow low-dimensional structures for research applications. MBE has given many contributions to the rapid expanding research-area of nano-technology and will probably continuing doing so. The MBE equipment, dedicated for Silicon/Germanium (Si/Ge) systems, at Karlstads University (Kau) has been studied and started for the first time. In the work of starting the system, all the built in interlocks has been surveyed and connected, and the different subsystems has been tested and evaluated. Service supplies in the form of compressed air, cooling water and electrical power has been connected. The parts of the system, their function and some of the theory behind them are described.

    The theoretical part of this master’s thesis is focused on low-dimensional structures, so-called quantum wells, wires and dots, that all are typical MBE-built structures. Physical effects, and to some extent the technical applications, of these structures are studied and described.

    The experimental part contains the MBE growth of a Si/Ge quantum well (QW) structure and characterisation by Auger Electron Spectroscopy (AES). The structure, consisting of three QW of Si0,8Ge0,2 separated by thicker Si layers, was built at Linköpings University (LiU) and characterised at Chalmers University of Technology (CTH). The result of the characterisation was not the expected since almost no Ge content could be discovered but an extended characterisation may give another result.

    Keywords: Silicon, Germanium, Molecular Beam Epitaxy, MBE, Quantum wells

  • 27.
    Falk, Erik
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Magnusson, Martin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Svetspåverkan på nickelaluminiumbrons2007Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    This degree project has been carried out for Rolls-Royce AB Kristinehamn that belongs to the marine division of the group. They produce permanent/adjustable marine propellers, pod- and waterjet systems. This work is a material survey concerning bronze propellers. The propeller blades are founded by sand-casting and during the founding process porosities arise and these are not desirable because they deteriorate the material's strength. These pits are TIG-welded.

    Rolls-Royce wants an increased understanding how these welding repairs influence the material properties in view of microstructure, hardness and strength.

    There are independent organizations, so-called register groups that have regulations concerning ship construction. Also, they have rules concerning repair welding of bronze propellers and different heat treatments after the welding. Rolls-Royce wants to have a summary of what the register groups say about heat treatment after repair welding of bronze propellers.

    Ten tensile test were carried out, two as reference, eight welded of which two were not heat-treat, two stress relieved at 315°C, two heat-treated at 500°C according to Rolls-Royce WPS (Welding Procedure Specification) and two annealed at 650°C. Welding fracture arose in all tensile test samples that were not heat-treated and stress relieved, but for the samples heat-treated at 500°C occurred one of the fractures in the basis material and for 650°C all fractures occurred in the base material. This shows that the annealing improves the properties of the weld compared to the base material. Thereafter, hardness measurement at the welding area and a microstructure analysis were carried out. The samples were compared in order to find the best heat-treatment and to compare with the one’s recommended by the register groups.

    After welding, the tensile strength and ductility were deteriorated, and with higher heat treatment temperatures, 500°C and annealing, higher values were gained. The yield strength increased some after welding and with subsequent heat treatments. The hardness in the weld and in the base material increased with the annealing.

    Only one change occurred in the microstructure and it was at annealing temperature, when the undesirable beta-phase, created from the welding, began to transform to alfa and kappa-phase.

    Higher heat treatment temperatures improved the material properties after welding, and annealing also changed the position of the fracture from the welding area to the base material.

    The register groups, which recommended higher heat treatment temperatures, should be more favorable than those saying heat treatment is not needed.

  • 28.
    Flognman, Jeanni
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Unneberg, Helen
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Wilén, Jaana
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Förvarings- och doseringsbehållare för torrvara2004Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta är ett 20 p examensarbete på Innovations- och designingenjörs-programmet vid Karlstads universitet i samarbete med företaget QDP. Projektets utgångspunkt har varit ett patent gällande en förvarings- och doseringsbehållare. Uppgiften var att formge patentets delar och genomföra en marknadsundersökning som tolkades med arbetsmetoden Quality function deployment (QFD). Målsättningen med projektet har varit att genomföra en marknadsundersökning samt ta fram koncept på formgivningen av patentets delar. En förstudie har genomförts med litteraturstudier, studiebesök och intervjuer. För närvarande finns inte någon liknande produkt på den svenska marknaden, de konkurrenter som finns, finns på den amerikanska marknaden. Uppdragsgivaren är därför intresserad av konsumenternas behov och synpunkter på den framtida produkten. För att utveckla en produkt som uppfyller kundens önskemål genomfördes åtta intervjuer med konsumenter och fyra intervjuer med fackfolk. Marknadsundersökningen resulterade i åtta kundönskemål som omvandlades till produktegenskaper med hjälp av QFD-matriser. Vårt arbete resulterade i tre olika koncept innehållande formgivning av behållare och mått samt dokumentation i form av matriser. Koncepten uttrycker enkelhet, har nyhetsvärde på marknaden och uppfyller de kundönskemål som framkom av QFD. Produkterna har en enkel och genomtänkt design som är anpassad till köket.

  • 29.
    Fransson, Christoffer
    Karlstad University, Faculty of Technology and Science. Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Accelerated aging of aluminum alloys2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to determine storage life for aluminum alloys it is essential to have a good knowledge on the accelerated aging behavior and the mechanical properties that are affected. The selected aluminum alloys are AA2017, AA6082, AA7075 and the study has been focused on their impact toughness and hardness relation to aging beyond peak conditions. To be able to plot the mechanical properties versus aging time and temperature, Differential Scanning Calorimetric runs have been the key to obtain supporting activation energies for a specific transformation. The activation energies have been calculated according to the Kissinger method, plotted in Matlab. Arrhenius correlation has also been applied to predict the natural aging time for long time storage in 30 degrees Celsius. It could be concluded that the results from the mechanical test series show that the constructed Arrhenius 3D method did not meet the expectations to extrapolate constant activation energies down to storage life condition. Scanning electron microscopy together with light optical microscopy analyses show how important it is to apply notches in proper test specimen directions and how precipitates are grown, as it will affect impact toughness and hardness.

    An ending discussion is held to explain how mechanical testing progressed and how other external issues affected the master thesis operations.

  • 30.
    Gladh, Jörgen
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Tensor products, Fusion rules and su(2) Representations2008Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    In this master thesis I have looked on two different kinds of representations of the Lie algebras su(2) and sl(2), and the tensor products of the representations.

    In the first case I looked at a tensor product involving a representation similar to one that appears in an article by A. van Tonder. This representation and tensor product was investigated mainly to get a good comprehension in the subject and to understand some of the problems that can arise.

    In the other case, which is the main problem in this thesis, I looked at a tensor product and representations that appears in an article by M. R. Gaberdiel. Here we deal with a tensor product of representations of su(2) with a specific value for the level at k = -4/3 and a specific eigenvalue of the Casimir operator at -2/9. This was done in the frame of finite dimensional Lie algebra and affine Lie algebra and not in the case of fusion rules as in the article by M. R. Gaberdiel.

    In both cases some of the calculations where done from in situ and the investigation of the representations behaviour due to the step operators, theirs eigenvalue and theirs weight system.

    Results and conclusions of the investigations are discussed in the last part of this thesis.

     

  • 31.
    Granström, Karin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    A Method to Measure Emissions from Dryers with Diffuse Leakages 2 - Sensitivity Studies2005In: Drying Technology, ISSN 0737-3937, Vol. 23, no 5Article in journal (Refereed)
  • 32.
    Granström, Karin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Biogenic emissions of monoterpenes in Sweden: a review with implications for modellingManuscript (Other (popular science, discussion, etc.))
  • 33.
    Granström, Karin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Emissions of monoterpenes an VOCs during drying of sawdust in a spouted bed2003In: Forest Products Journal, ISSN 0015-7473, Vol. 53, no 10Article in journal (Refereed)
  • 34.
    Granström, Karin
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Emissions of volatile organic compounds from wood2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The central aim of this thesis is to support the efforts to counteract certain environmental problems caused by emissions of volatile organic compounds.

    The purpose of this work was (1) to develop a method to establish the amount of emitted substances from dryers, (2) to determine the effect of drying medium temperature and end moisture content of the processed material on emissions of monoterpenes and other hydrocarbons, (3) to examine the emissions of monoterpenes during production of pellets, and (4) to examine the natural emissions from forests with an eye to implications for modelling.

    The measurement method (1) resolves the difficulties caused by diffuse emissions, and also solves the problems associated with high moisture content of the drying medium. The basic idea is to use water vapour to determine the exhaust flow, while a dry ice trap is used both to preconcentrate emitted volatile organic compounds and to determine the moisture content of the drying medium. The method as used in this paper has an uncertainty of 13% using a 95% confidence interval.

    Emissions from a spouted bed (2) in continuous operation drying Norway spruce sawdust at temperatures of 140°C, 170°C or 200°C was analysed with FID and GC-MS. When the sawdust end moisture content was reduced below 10%wb, emissions of terpenes and volatile organic compounds per oven dry weight increased rapidly. Increased temperature of the drying medium increased the amounts of emitted monoterpenes when sawdust moisture content was below the fibre saturation point.

    Examination of sawdust and wood pellets from different pellets producers (3) revealed that most of the terpene emissions happened during the drying step, with rotary dryers causing higher emissions than steam dryers. Almost all of the volatile terpenes remaining in wood after drying were released during pelleting. When sawdust with higher moisture content was used in the pellets press, the terpene emissions were increased.

    Terpenes emitted naturally from vegetation can have an adverse environmental impact. Factors affecting terpene emissions from tree species in Sweden were reviewed (4). Models for prediction of terpene fluxes should include not only temperature but also light intensity, seasonal variation, and a base level of herbivory and insect predation. Prediction of high concentrations of ambient terpenes demand sufficient resolution to capture emission peaks e.g. those caused by bud break.

  • 35.
    Granström, K.M.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    A Method to Measure Emissions from Dryers with Diffuse Leakages, Using Evaporated Water as a Tracer2003In: Drying Technology, ISSN 0737-3937, Vol. 21, no 7Article in journal (Refereed)
  • 36.
    Gunnarsson, Mikael
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    En studie av derivatakunskapen hos gymnasieelever2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Denna uppsats presenterar en undersökning om gymnasieelevers kunskaper i derivata. Undersökningen syftar till att jämföra både elevernas teoretiska förståelse samt deras praktiska kunskaper med de krav som anges av kursplaner, läroböcker samt rådande undervisningspraxis. Undersökningen syftar också till att utreda om det råder något samband mellan elevernas teoretiska förståelse av derivata och deras praktiska kunskaper på området.

    Undersökningen är bedriven i provform där eleverna under två tillfällen besvarar två olika prov, ett av teoretisk karaktär samt ett av praktiskt beräknande karaktär. Proven är gjorda så att de representerar de rådande kursplanernas krav på godkänd nivå. Det teoretiska provet är upplagt så att eleverna språkligt ska förklara en rad grundläggande teorier och användningsområden inom derivata. Det praktiska provet består av räkneuppgifter av samma karaktär som eleverna är vana vid från lokala samt nationella prov. Undersökningsgruppen består av 22 stycken elever som går det tekniska programmet i årskurs tre.

    Resultaten visar att det i undersökningsgruppen råder ett samband mellan teoretisk förståelse och praktisk kunskap. Detta samband är beräknat mellan de olika provdelarnas resultat och är statistiskt säkerställt. Frågan om eleverna kan sägas ha visat tillräckliga kunskaper för att enligt kursplanen anses vara godkända är behandlad i diskussionsform och presenteras i slutet av rapporten. Där återfinns även en diskussion om undersökningens brister och generaliserbarhet.

  • 37.
    Gustafsson, Fredrik
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Gasturbinventil2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 38.
    Gustavsson, Anders
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Klimatsimulering av ett kontorsrum: Hur de termiska stigkrafterna påverkar ventilationseffektiviteten2006Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    Abstract

    In urban societies people spend more and more time indoors, which put great demands on the indoor environment. If the ventilation is to manage the removal of unwanted substances in the indoor air, a good mixing of the air is required. The question arises that, whether the buoyancy forces will counteract a good mixing of the indoor air or not?

    This report aims to clear up the difficulties whether you need to consider the buoyancy forces or not, when adjusting a ventilation unit. For studying the indoor mixing of the air a two dimensional model is constructed in COMSOL Multiphysics. In this model several supply air temperatures is simulated to see how much the temperature affects the mixing of the air.

    The physical relations that are being used in this model is the Navier-Stoke’s equation for Non-Isothermal flow, the relations for General Heat transfer and the relation for Convection and Diffusion. These relations exist as tools in COMSOL Multiphysics.

    It wasn’t possible to get the model to converge at low air velocities, because the model is dependent of accuracy in the field of cm or mm.

    The lowest velocity, in the zone of occupancy, which the model was able to simulate was 0.5 m/s but it takes velocities below 0.2 m/s to fulfill the indoor climate requirements due to the problems concerning draft.

    It was possible to see that the buoyancy forces affect the mixing of the air to a certain degree, despite high air velocities.

    Unfortunately it wasn’t possible to see to what degree you have to consider the buoyancy forces when adjusting a ventilation unit. To see the affects of the buoyancy forces or not, is highly dependent on the velocity of the air. Because the force generated by the supply air increases by the square of the velocity change.

    When constructing a more detailed model, which is a requirement for convergence when having low velocities, the memory of the computer isn’t enough.

    The results of the simulations show that a computer with more calculation capacity, than the Karlstad University can offer, is needed to make a successful simulation.

  • 39.
    Göthberg, Lisa
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Kan skor flyga?: Ett examensarbete om skor2007Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    My dream is to work as a shoe designer. Due to this I wanted to learn ”everything” about shoes in my degree project. I was hoping to get in touch with a company so I could design a small collection of shoes, and I found the company Kavat in Kumla which developes and manufactures children’s shoes. Though I wanted my product to be a part of the next summer collection, I had to hurry up with the task and make the deeper research in a second place. The first part of this report is for this reason about the job I did for Kavat and the second part is a research about development and manufacturing of shoes, the history of shoemaking and also the history of shoe fashion.

    The task was to design a small collection of baby shoes that was to suit for a given last and it would be included in the summer collection of 2006. The purpose was to offer small children practical and funny shoes and also design shoes that fitted both boys and girls. Shoes have been manufactured in the factory in Kumla since 1945 and today it is one of the last manufacturers in Sweden. Kavat’s target group is children between 0-5 years and it is a genuin trademark with high quality demands. On the market today we can see typical groups of shoes like sportshoes and it is common with big differences between boys’ and girls’ shoes. To get inspired I looked at both children’s shoes and shoes for adults. I also found inspiration in clothes and toys. To get the collection mutually connected a theme was to be used and some examples was insects and fairytales. I sketched a lot of ideas and send them to Kumla and when I visited the factory a second time we made a prototype of one of my sketches. Though the time was running we could not realize further ideas but instead we developed the one we had made so it became perfect.

    The result was a pair of playful sandals and I chose four colours that wasn’t typical for boys or girls. This was changed after I had gone and they chose one red and one blue colour instead. The reaction from the retailers was that they looked nice and funny but they were a little too daring, but yet they sold in 800 copys. I am satisfied with my sandals and I really think people will see them among all the other shoes in the stores.

    After reading a lot of books about shoes and visiting at two shoe companys and one museum, I have managed to compile a material about development and manufacturing of shoes, the history of the shoe industry and the history of shoe fashion. It wasn’t easy to find good litterature about shoemaking but I finally found a few books that was useful. Now I know the fundamental skills but probably it damands a lot of experience to be able to manufacture shoes in a good way. The educational visit at Ericsson & Saether gave a lot of information about what the branch of shoes looks like today with companys that just decide what the shoes will look like and then they orders everything from Asia. My reflection is that companys looks in a short perspective when they just buys the cheapest things, and don’t go in for durable marketing with reliable trademarks and just manufacturing.

  • 40.
    Hansson, Anna
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Egenkontrollsystem: Con-Form Töcksfors AB2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    The company Con-Form Töcksfors AB manufactures bathroom modules. Their existing self control system is lacking and it’s missing in routine. From this follows that it is hard to prove that damages discovered after delivery are not caused by Con-Form Töcksfors AB. The goal of this project is to design a self control system for Con-Form Töcksfors AB encompassing both planning and production.

    The working thesis for this paper is as follows: How should a self control system be constructed so that Con-Form Töcksfors AB know they deliver goods of the right quality and how should this new system become routine and a natural part of the work procedure.

    To do the self control system as thorough as possible a study of both planning and production is necessary. In order to design a new control system, the author was responsible for the planning of Steinhammerveien, Oslo. A longer on-site study of the manufacturing of bathroom modules, with detailed observations of the procedures, has also been made.

    The present system consists of three parts, control of the managing of drawings, plasticized drawings and a checklist in the production stage.

    In the new system three parts have been added: a checklist to be used in the planning stage, posters and an index to be used in the production stage.

    These new additions cannot replace the old control system but should be seen as a complement. All parts of the old system will there for remain.

  • 41.
    Hansson, Linus
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Nyberg, Andreas
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Wahlberg, Jonas
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Fuktsäkringsarbete i ett byggprojekt: – En undersökning om hur byggprocessens aktörer arbetar för att uppnå samhällskraven2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    According to Swedish law you are not allowed to construct buildings in a way that may result in jeopardizing people’s health. Despite this fact buildings are constructed in such way that health problems accurse. This composition deals with a building-project and how its actors works regarding to humidity that effects buildings. The purpose of this essay is to look into how in a project one works with eliminating risks concerning humidity and also the level of demands that are made to secure the construction. The objective is to point out where in the building-process risks appears when it comes to securing humidity in buildings, but also to suggest how to make improvements. The method is based on a study of laws and ordinances that concerns humidity in buildings. The way the building line, and the knowledge within it, is used in a project to secure the building from humidity has also been studied. Interviews has been made to look into in what the role building department, entrepreneur, constructor and supplier has regarding to humidity in buildings. This essay is demarcated to multifamily buildings in Karlstad built in own-regime. The result shows that the risk of damage as a consequence of humidity is founded in all phases in the building-process and that all actors of the process are a part of the problem. The result also shows that actors in the project is well averred of the problem with humidity but that there is not enough demands on documentation and on how to work with experiences from earlier project. To work in a more efficient way one should draw up a description for the project regarding to the risk of humidity in the building. This description should be made in co-operation with someone who has the right knowledge concerning how to draw up a description, and that also makes the project safe from humidity point of view. The result also shows that it is necessary to educate all actors that risks contributing to the problem with humidity in buildings.

  • 42.
    Hedberg, Stefan
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Reed-Muller kod av första ordningen2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    En säker informationskanal med hög överföringskvalitet krävs i dessa dagar när informationsöverföringen ökar för varje år som går. Det finns olika sätt att skapa detta. Antingen genom att se till att överföringsmediet är av mycket hög kvalitet eller att skapa en skyddsmekanism som gör att de överföringsfel som kan uppstå kan detekteras och även korrigeras om man önskar detta. Denna uppsats handlar om detta, att kunna detektera och korrigera fel. Denna gren inom matematiken kallas kodningsteori.

    Uppsatsen presenterar grunden för kodningsteorin, för att sedan presentera några vanligt förekommande kodningsalgoritmer, Hamming koder, BCH koder, Reed-Solomon. Jag går in på djupet av en av de absolut äldsta kodningsalgoritmerna, en kod som presenterades 1954 av David E. Muller, något senare presenterade en annan föregångare inom kodningsteori, Irving S. Reed, en avkodningsalgoritm för Mullers kod. Denna kod blev känd under namnet Reed-Muller kod.

    Jag presenterar teorin bakom Reed-Muller kod och hur ett Reed-Muller kodord skapas med hjälp av teorin. Jag visar också hur man avkodar Reed-Muller kod med hjälp av olika algoritmer där Irving S. Reeds algoritm står i centrum. För att testa kodning och avkodning i simulerad verklighet används datorprogrammet Matlab. Slutligen presenteras hur kodnings- och avkodningsalgoritmer kan skapas med hjälp av grindnät.

  • 43.
    Hirvonen Grytzelius, Joakim
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Atomic Force and Scanning Tunneling Microscopy Studies of Single Walled Carbon Nanotubes2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    In this diploma work I present the first experimental investigations

    of carbon nanotubes at Karlstads University. Raw nanotube powder

    of single walled carbon nanotubes have been dispersed primarily in

    1,2-dichloroethane. The solutions have been spincoated on Au(111)

    substrates. In order to determine the solubility of carbon nanotubes

    in the solution the samples have been investigated in an atomic force

    microscope.

    Single walled carbon nanotubes deposited on a Au(111) substrate

    have been investigated in a scanning tunneling microscope. Atomically

    resolved STM images of single walled carbon nanotubes were obtained.

    Scanning tunneling spectroscopy spectra was taken on a tube revealing

    its chirality. The measured data from the nanotubes was compared to

    calculations and confirmed their properties.

    Dry direct contact transfers of individual single walled carbon nanotubes

    have been done as a first step when trying to deposit carbon

    nanotubes on reactive surfaces in ultra-high vacuum. Individual nanotubes

    were found, confirming the success of dry direct contact transfer.

  • 44. Hjertsén, David
    et al.
    Sjöström, Johnny
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Bergström, Jens
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Näsström, Mats
    Finite Element Simulation of the Tool Steel Stress Response As Used in a Hot ForgingManuscript (Other academic)
  • 45.
    Holmquist, Linn
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Elevers inställning till matematik: - en jämförande studie av elevers uppfattning av matematikämnet och matematikundervisningen2007Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    Based on earlier experiences of mathematics and mathematical learning, both as a student and as a teacher, I became more and more interested in how well the publicly accepted opinions about mathematics as an uninteresting, difficult and “geeky” subject corresponded to reality. What do Swedish pupils really think about mathematics and is it possible to identify any differences in their attitudes based on the pupils’ age?

    From this point of view the following questions were formulated:

    ·What are pupils’ attitudes towards mathematics in grades 3, 6 and 9 and how do they conceive their learning conditions?

    ·Is it possible to detect any differences in the attitudes and preferences depending on the pupils’ age?

    The result of this study compares well with previous studies done in this and overlapping fields and indicates that:

    ·Younger pupils tend to have a better liking of mathematics but with increasing age that interest fades out.

    ·Most pupils, without regard to age, consider mathematics to be one of the most important subjects, despite the fact that many pupils also find mathematics difficult and boring.

    ·For pupils of all ages, the teacher is the most important factor in the learning process. Older students have more specific demands on the teacher for knowledge and pedagogical skills.

    ·A high noise level, talking and disturbances in the classroom are the most bothering elements when it comes to learning mathematics. Especially the younger pupils find it hard to concentrate during such conditions while older students are disturbed if they feel that the teacher is being insufficient in his or her professional behaviour.

    Key words: Attitudes, pupils, mathematics, learning

  • 46.
    Högblad, Jon
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Auger Electron Spectroscopy of Controlled Delaminating Materials on Aluminium Surfaces2008Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    This master thesis in physics mainly treats Auger spectroscopy of interfaces that has been adhesively bond together with so called controlled delaminating materials (CDM). CDM is a new technology which involves adhesives with the distinctive property that they by the appliance of electricity can be released from a substrate. The reason for using Auger spectroscopy was that it gives a surface sensitive view of the chemical composition of the samples examined and this was believed to give hints of the mechanisms behind loss of adhesion. The samples were so called laminates which is an aluminium foil, CDM adhesive, aluminium foil structure. As expected Auger spectroscopy produced some promising results, especially regarding the breakdown of a certain anion contained into the examined CDM adhesive. This awoke new questions regarding how this anion was decomposed and the idea that it could be due to hydrolysis took form. The by far most important result within this work is that the anion breaks down. This could lead to the formation of hydrofluoric acid if this breakdown in fact is due to hydrolysis and the hydrofluoric acid could then react with the aluminium causing loss of adhesion. This could be the good starting point of a continuing work on CDM.

  • 47.
    Jackman, Henrik
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Surface temperature measurement on a Yankee cylinder during operation2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Yankee cylinder is used in most of Metso Paper's machines. It is used in the drying and creping process. Since the outcome of these processes largely affect the paper's final quality it is important that the Yankee cylinder behaves in a controlled fashion. One important parameter affecting the behaviour of the Yankee cylinder is its surface temperature.

    The objective of this thesis was to search for and evaluate methods for measuring the surface temperature of a Yankee cylinder during operation. Metso Paper is looking for a method having an accuracy of ΔT = 1°C, a response time of t<10 ms, and being portable.

    Three different instruments were tested during the thesis:

    • Thermophone, a contact measurement device currently used by Metso Paper.
    • RAYNGER MX4, a pyrometer from Raytek.
    • FLIR P640, a thermographic camera with a 640x480 focal plane array from FLIR.

    The instruments were tested by performing measurements on Metso Paper's pilot machine in Karlstad during operation. The measurements revealed drawbacks for all three instruments. The biggest drawbacks of the Thermophone was its response time, t~5 min, and its dependence on the frictional heating of the teflon cup. The frictional heating causes the measured temperature to increase even after 15 min making it hard to know when to stop the measurement. How much the frictional heating affects the measured temperature was difficult to analyse, making it a suggestion for future studies.

    The biggest drawback of the pyrometer and the thermographic camera is the measurement error due to emissivity errors. Since the Yankee cylinder have a varying surface finish the emissivity varies a lot along the surface introducing temperature errors as large as ΔT=30°C.

    Two methods that claim to be emissivity independent were investigated; double-band and gold cup pyrometers. Double-band pyrometers require the target to be a grey body and for it to have large temperatures, T>300°C, making this method unsuitable for measuring the surface temperature of the Yankee cylinder.

    Gold cup pyrometers require the gold hemisphere to have a reflectance of ρ=1. Because of the environment surrounding the Yankee cylinder it would be difficult keeping the gold hemisphere as clean as required making this method unsuitable as well.

  • 48.
    Jakobsson, Andreas
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Mossberg, Magnus
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Rowe, Michael D.
    Smith, John A. S.
    Frequency-Selective Detection of Nuclear Quadrupole Resonance Signals2005In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 43, no 11, 2659-2665 p.Article in journal (Refereed)
    Abstract [en]

    Nuclear quadrupole resonance (NQR) offers an unequivocal method of detecting and identifying both hidden explosives, such as land mines, and a variety of narcotics. Unfortunately, the practical use of NQR is restricted by a low signal-to-noise ratio (SNR), and means to improve the SNR are vital to enable a rapid, reliable, and convenient system. In this paper, we introduce a frequency-selective approximate maximum-likelihood (FSAML) detector, operating on a subset of the available frequencies, making it robust to the typically present narrow-band interference. The method exploits the inherent temperature dependency of the NQR frequencies as a way to enhance the SNR. Numerical evaluations, using both simulated and real NQR data, indicate a significant gain in probability of accurate detection as compared to a current state-of-the-art approach.

  • 49.
    Jansson, Lillemor
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Modin, Victoria
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Bil- och järnvägstrafikens inverkan på inomhusmiljön med avseende på ljud och luft: - I planerade bostäder på Haga2006Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    NCC has given us a commission to investigate a planned housing area in Haga, Karlstad, situated close to the traffic route Hagaleden and the railway. The housing area consists of one hundred apartments in five different houses. The houses are linked to each other by balconies with glass panels. A long carport is situated between Hagaleden and the housing area to absorb part of the noise from the road. The design of the housing area is creating a silent backyard. The idea of building houses in this place is to create an attractive living in central town and close to the river.

    The air and sound level inside of the planned houses were studied. The major problem is that the noise from the railway traffic and the car traffic are of different kind. The railway traffic creates high maximum sound levels and the car traffic creates high equivalent sound levels. The different kinds of sound levels consist of high and low frequency which means that different measures have to be taken to reduce both types. The emission from the car traffic is the major problem for the air quality, but it is uncertain how much of the emissions that passes to the inside of the houses.

    The result shows that the noise is the main problem. Despite the suggested noise reduction measures, the noise exceeds the limits of the building regulations on the facade of the houses. If the houses are to be built, they will not fulfill the regulations on this point. The noise is the major problem but there are many other factors that influence the air and the sound in the buildings. This essay describes different factors and every part of it ends with a checklist that can be used to create a good indoor environment. It is important for the quality of the air in the apartments that the ventilation system is correctly dimensioned for the building and is well dimensioned. It is recommended that the ventilation system should be complemented with an air treatment unit.

    The purpose of this checklist is to find an easy way to ensure that the demands and regulations of the norms are fulfilled. The items are all listed in an appendix in the work, but they need to be developed to be used easily.

    In the conclusion a suggestion on measures that could make the environment in the apartments better is presented. For example, the design of the balconies has been changed to prevent the noise from getting into the backyard. Suggestions on measures on the outside of the buildings are also presented; an example of this is silent asphalt, an extended carport and noise barriers.

  • 50.
    Johansson, Arvid
    et al.
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Fjällström, Tobias
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Intergrerad parallellaxeldrift2008Student thesis
    Abstract [en]

    Students at Karlstad University has carried out a degree project within the Study Programme in Mechanical Engineering. The projects main purpose is to apply the knowledge of the Programme and shall be carried out together with a company. The project shall be driven out independently and lead to both an oral and a written presentation.

     

    This report describes a work of improvement for Metso Paper in Karlstad, referring to the motor and drive train mechanism of two screw jacks that is used to tightening the wind or felt in the paper machine. This project has lead to a complete proposition, a description of manufacturing and is founded upon an asynchronous motor with a thoroughgoing drive shaft with two planetary gear boxes on both side of the motor. This solution is a result of an evaluation of different concept (chapter 2), regarding common motors and gears on the market. The reason that we used this motor and gears is mainly due to the minor space requirements that such solution can accomplish, with an inline drive train. The solution shall be able to fit different configurations of screw jacks, regarding the size of motor, ratio of gears and the length between the jacks. This is mainly done with adjustments of the holder, to fit the motor and the rest of the drive train. But this is basically the same solution. Subsequently the motor, gears and other components is selected accordingly to this report and we have chosen to show our solution fully on the screw jacks A50 that is placed in configuration that is about 6 m apart. Further, due to the conditions in the paper machine, a cover has been designed to prevent the paper pulp to come in direct contact with motor and drive train.

     

    The requirements that Metso Paper has set up is that the solution should be able to come as a module, meaning in our case that the motor, drive train and holder can be delivered as one unit together with a parallel shaft that connects the two screw jacks.      

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