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  • 1.
    AlMotasem, A
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics. Department of Physics, Faculty of ScienceAssiut University Assiut Egyp.
    Bergström, Jens
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Gåård, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Holleboom, Thijs Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Atomistic insights on the wear/friction behavior of nanocrystalline ferrite during nanoscratching as revealed by molecular dynamics2017In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 65, no 3, 101- p.Article in journal (Refereed)
    Abstract [en]

    Using embedded atom method potential, extensive large-scale molecular dynamics (MD) simulations of nanoindentation/nanoscratching of nanocrystalline (nc) iron have been carried out to explore grain size dependence of wear response. MD results show no clear dependence of the frictional and normal forces on the grain size, and the single-crystal (sc) iron has higher frictional and normal force compared to nc-samples. For all samples, the dislocation- mediated mechanism is the primary cause of plastic deformation in both nanoindentation/nanoscratch. However, secondary cooperative mechanisms are varied significantly according to grain size. Pileup formation was observed in the front of and sideways of the tool, and they exhibit strong dependence on grain orientation rather than grain size. Tip size has significant impact on nanoscratch characteristics; both frictional and normal forces monotonically increase as tip radii increase, while the friction coefficient value drops by about 38%. Additionally, the increase in scratch depth leads to an increase in frictional and normal forces as well as friction coefficient. To elucidate the relevance of indentation/scratch results with mechanical properties, uniaxial tensile test was performed for nc-samples, and the result indicates the existence of both the regular and inverse Hall-Petch relations at critical grain size of 110.9 angstrom. The present results suggest that indentation/scratch hardness has no apparent correlation with the mechanical properties of the substrate, whereas the plastic deformation has.

  • 2.
    Carlson, Philip
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Konstruktions- och Materialförbättring hos Superkritiska Ventiler2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
  • 3.
    Daouacher, Maria
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Rearward facing travel for every child's safety2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study was made within the Child Safety group at Volvo Car Corporation.  The purpose of this bachelor thesis was to study the different aspects of rearward facing child restraint systems, which is the safest way for small children to travel, in order to suggest improvements in the development of child restraint systems. The studies included scientific articles regarding child safety and fatally injured children in car accidents, both in Sweden and internationally. The overall aim is to find factors that enables the increase in usage of rearward facing child restraint systems, including the increase of usage time to as long as possible.

     

    Swedish accident data, obtained by the Swedish Traffic Data Acquisation, was studied. It was found that the fatally injured children during car accidents in Sweden between the years 2000-2016 commonly were involved in extraordinarily accident scenarios with an outcome independent of how they were restrained. The literature study and the survey that was made were both supporting the statement of inconvenience while using rearward facing child restraint systems. The inconvenience often corresponded to different types of misuse. The main issue with rearward facing according to the responding parents was lack of leg space, both for their child but also for the driver and the front seat passenger. These issues made some parents turning their children forward facing at early age, whereas they could still fit in the rearward facing child restraint system.

     

    One key in order to increase the global use of rearward facing child restraint systems lies in changes of the materials and design. A more lightweight and compact design is suggested, providing a more spacious travel environment for the children and easier mounting for the parents. The need of education is apparent, preferable by means of social media due to the easiness of sending information globally with low cost.

  • 4.
    Häggström, Per-Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Omkonstruktion av treaxlig plockrobot och dess plockverktyg2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This thesis has treated a three-axis robot which task is to serve a larger test machine tomove the modules to be tested, from the storage to the test site. The robot is composed ofthree linear actuators; two standard components of ball screw type and a custom-builtactuator of trapezoidal type. The work has mainly focused on the custom-built device to seeif it could be replaced with a standard component. Part of the work has been to look into thepicking tool and to see if there are any possibilities to improve its function.The report presents two different proposals which I decided to call Robot 1 and Robot 2 andthey aim to address the problems arising in the purpose-built linear unit and the X-axislinearity problems. Robot 1 focuses on eliminating the problems that arise around therobot's X-axis, with such simple means as possible and without making excessive materialchanges. The idea behind the solution of Robot 1 is also to be able to apply it onto existingmachinery without too much interference. Robot 2 is significantly more advanced and alsoimplies considerable material changes. The advantage of Robot 2 is that it takes into accountboth the problems with the X-axis and Y-axis, and should absolutely be considered on newmachines, but also for existing machines. For the picking tool the thesis presents the solutionin the form of both a modified existing vacuum tool and a brand new pneumatic gripper forRobot 2 which differ from the vacuum system. I think that the vacuum tool presented shouldbe considered to be implemented even if no other modifications are made on the robotbecause of its simple construction.The thesis presents the functions and problems with the current robot and its picking tool.For the described problems the different solutions have been presented, partly by findingcompletely new market components but also through new self-designed components.During this time, choices of materials and material dimensions have been based onoverestimates and previous material selections, which later were controlled by using FEManalysisin CAD-environment.The work is considered to have gone well and the goals that have been set have beenachieved in a satisfactory manner.

  • 5.
    Jansson, Adam
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Further development of Sand Bed Burner2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    To determine whether a weapon system meets the requirements set for insensitivity, the system is getting exposed for special tests. One of these tests shows how the system reacts when it ends up in a fire. This test is called the "Fast Cook-Off (FCO) Test", called FCO-test, and performed with a Sand Bed Burner (SBB). According to primary testing provision, the fuel for this test is used of jet fuel such as Jet A-1. A project at Bofors Test Center (BTC) is in progress to use an alternative fuel of Liquefied Petroleum Gas (LPG). This fuel is very advantageous compared to jet fuel in terms of environmental impact, work environment and testing costs.

    The aim of this thesis is to improve the existing test equipment considering fire over the entire surface and solve the problems with dropped gas flow and freezing of gas bottles.

    SBB works in the sense that the new petrol LPG streams into the SBB and expands in the free space below the sand bed before the gas will diffuse through the bed of sand and the fire engulfs the object.

    LPG is a condensable gas that requires oxygen. LPG exceed from liquid to gas phase and needs a large lateral surface to take up more energy which results in better evaporationto the phase transfer. Reaction products from complete combustion of LPG are only water vapor and carbon dioxide, the same as in your exhaled air.

    To solve these problems it was needed to change P11 composite bottles to P45 steel bottles to get a longer evaporation and larger lateral surface. Four flow inlets instead were used of one into SBB for a better stream in the free space under the sand bed. Propane regulators used to get a lower and more constant flow to avoid freezing. Compressed airconnected tothe SBB to geta mix between oxygen and LPG.

    The result shows in higherheat radiation efficiency even though the flow was settled down to 1/3 with the new propane regulators. In test 2 the value was 37 kW/m2 and in test 7 it was around 57 kW/m2. Because of a smaller flow and bigger steel bottles the freezing disappeared. Smaller grain of sand together with four inlets and compressed air gave a more complete combustion.

  • 6.
    Karlsson, Marcus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Implementering av LEAN i småskalig mejeriverksamhet2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Wermlands Mejeri AB startade under hösten 2015 som en ny leverantör av mjölk och grädde för de värmländska konsumenterna. Under det dryga året som mejeriet haft sin verksamhet igång har det skett flera investeringar och produktionskapaciteten har ökat. För att uppnå den nya kapaciteten ställs det krav på produktionsutrustningen. Den måste fungera utan avbrott för att få en jämn och kontinuerlig produktion samtidigt som kvaliteten i livsmedelsbranschen är högsta prioritet av hygieniska skäl.

    När mjölk tillverkas genomgår den ett antal processteg för att kunna säljas. Detta projekt är avgränsat till förpackningssteget och förpackningsavdelningen.

    Syftet med projektet är att kartlägga de åtta slöserierna som beskrivs i produktionssystemet Lean. Målet är att efter kartläggningen kunna ge konkreta förslag till förbättringar för att minska en eller två slöserier.

    Genom observationer, intervjuer och insamling av data har slöserierna analyserats och förbättringsåtgärder har föreslagits med hjälp av verktyget 5S. 5S är ett verktyg inom Lean som beskriver hur saker kan förbättras och hur det kan ske.

    Två av de åtta slöserierna valdes ut för att analyseras mer och ge förbättringsförslag. De två blev rörelser och defekter. Genom att använda sig av de två första S:en, sortera och strukturera så kan rörelser minskas för personalen i förpackningsavdelningen. Defekterna uppstår i de olika maskinerna och kan minskas genom att arbeta mer förebyggande. Genom att införa ett underhållssystem och kartlägga vart och varför defekterna uppstår så skapas en bild av hur defekterna uppstår. Att arbeta systematiskt med de delar som orsakar problem i maskinerna och föra statistik över dem kan antalet defekter minska. Ett avvikelserapporteringssystem bör införas för att se hur ofta och var defekterna uppstår.

    Projektet kan ses som ett första steg för att införa Lean i Wermlands mejeris verksamhet och kan användas för vidare studier inom området.

  • 7.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Microstructure and phase constitution of Ti-SiC coatings fabricated by selective laser melting2013Conference paper (Refereed)
  • 8.
    Lennartsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Förbättring av Barillas interna materialflöde: Huvudfokus mot produktionslinje 192014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Som en del i Maskiningenjörsutbildningen vid Karlstads Universitet har detta examensarbete utförts under höstterminen 2013. Uppdragsgivaren är Barillagruppen som är världens största producent av pasta och pastasåser samt Europas ledande bagerikoncern. I Sverige känner vi främst igen varumärkena Barilla och Wasa, den senare är världens största producent av knäckebröd. Produkter med varumärket Wasa produceras idag vid fabrikerna i Filipstad och i Celle i Tyskland. Det är i fabriken i Filipstad som detta examensarbete är utfört.

    Arbetets utformning har skett till en början genom att undersöka och bekanta sig med fabriken och dess processer. En nulägesanalys skapades för att identifiera de områden som har stor förbättringspotential, vid nulägesanalysen analyserades främst transporter, lagerplatser och transporttider.

    Ett förbättringsarbete på produktionslinje 19 arbetades fram utifrån den data och informationsom nulägesanalysen gett. Utformningen av det befintliga mellanlager som idag används vid linjen, arbetades om till ett mer standardiserat lager. Materialet som går igenom lagret kommer att användas enligt metoden FIFO, ”First in first out” på ett mycket bättre sätt än tidigare. Transporttiden är reducerad med 9,54 timmar per vecka för de 2 främst använda förpackningsmaterialen till PL18-19, nämligen well och innerpapper.

    Det har även getts ett nytt layoutförslag som skulle förbättra materialflödet i paketeringen genom kortare transportsträckor, tydligare beläget lager och lättåtkomlighet för de transport och servicemän som ansvarar för transporten av förpackningsmaterial i fabriken.

  • 9.
    Lindgren, Alexander
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Implementeringsutmaningar vid införande av tillståndsbaserat underhåll på reglerventiler inom ett kartongbruk.: En fallstudie utförd på ett kartongbruk i Sverige.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 10.
    Mussa, Abdulbaset
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Wear characterization and wear mapping of a coated cutting tool: Development of cutting tool test fixture and wear testing2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wear mechanisms of the cutting tools are well investigated worldwide. Usually researchers use the cutting process itself, turning by single point cutting, as their investigation method, which includes turning a metal cylinder with a pre-selected work-material and predetermined cutting conditions. Thereafter the tool worn surface is examined by scanning electron microscopy in order to characterize the tool wear mechanisms and tool failure. However, this may be the most appropriate way to investigate the wear mechanisms which occur during machining since it simulates the real operation. Metal cutting involves extreme conditions such as high temperature and high-pressure and the different condition results in different wear modes on the insert’s surface. The wear modes are overlapping and the transition boarder between them are not sharp making it difficult to obtain a detailed information of wear mechanisms. Because of these reasons many researchers try to refine the machining to a single condition e.g; high pressure, at the laboratory level in order to characterize the wear mechanisms and to get a more detailed information.

    In this thesis the wear tests of the cutting tool are performed by using a slider-on-flat-surface (SOFS) wear tester. SOFS involves a normal load, which applies to the sample and a tangential force that enables the sliding of the sample against a counterface. To enable conducting the wear tests in SOFS a newly design of tool holder was prepared. The wear tests were performed at different contact conditions and the stainless steel EN 1.4310 was used as the counterface material. After the tools were tested, the worn surface of the tool was examined by optical light microscopy and scanning electron microscopy in order to identify the wear rate and wear mechanisms.

    At low load the dominating wear mechanism was adhesive wear. The adhesive wear was induced by material pick-up during sliding i.e. material from the counterface was transferred to the insert’s surface. Further sliding results in delamination of the insert surface and removal of a part of the coatings material.

    At high load the dominating wear mechanism was a combination of severe adhesive wear and fracture of the coating material. The fracture of the coating material occurred because of overloading. Coating defects promote crack formation under high load and these cracks propagate through the coating during sliding movement and result in microchipping of the coating material.

    This procedure does not simulate the metal cutting but it still gives an understanding of the behavior of the coating material when it is exposed to a high mechanical stress.

  • 11.
    Rådberg, Malin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Design of Experiment for Laser cutting in Superalloy Haynes 2822016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project aims to investigate the effect of varying different laser cutting parameters on the laser cut surface. The parameters that were varied were cutting speed, beam effect, gas pressure and focal point. The statistical method Design of Experiment was used to plan the experiments and two full factorial test plans were set up, one with argon as cooling and protective gas and one with nitrogen. Sheet metal consisting of the superalloy HAYNES ® 282 with a thickness of 2,54 mm was investigated. Samples from the material were cut with different laser cutting parameters according to the test plans. The samples were evaluated by measuring cracks, recast layer thickness, surface irregularity, burr height and distance to beam deflection point on the cut surface. The resulting data was inserted as responses into the statistical program Modde 10.1 for analysis.

    Modde 10.1 provided models of high significance for the responses of Recast layer, Tav; Recast layer, Tmax; Burrheight, max and Distance to deflection point for the argon series and Recast layer, Tav and Recast layer, Tmax for the nitrogen series.

    The results showed that both recast layer thickness and burr height decreases with increased values of cutting speed, gas pressure and focal point as well as decreased values of beam effect within the parameter window investigated. They also showed that distance to deflection point increased with increasing values of gas pressure and focal point and with decreased values of cutting speed and beam effect within the parameter window.

    The results also showed that for the samples cut with argon as cooling and assistant gas the parameters that affects the recast layer thickness the most are focal point and gas pressure, whereas for the nitrogen series it is gas pressure and beam effect. The parameter with greatest effect on burr height is the cutting speed and for the distance to deflection point it is focal point and gas pressure that have the greatest effect.

    When comparing the argon and the nitrogen series to each other it can be seen that the argon series generate less recast layer from the entry of the cut until between 60 – 80 % into the cut, after which the argon series bypasses the nitrogen series in amount of recast layer produced in the cutting process in the majority of the places measured.

  • 12.
    Wallberg, Elin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    Utveckling av empatistation för att få förståelse för hur det är att leva av lite luft2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project is a thesis for the Bachelor of Science in innovation and design at Karlstad University. Behind the misson is Experio Lab who uses empathy tools as part of their working methods. Empathy tools consist of various tools in order to simulate different disabilities.

    The first part of the project focuses on what simulation tools are and the different kind of simulation tools intended to provide empathy for the user. Gradually the project evolved to develop one of the existing empathy tools in Experio Lab´s portfolio.

    During the project Development of simulation tools to get understanding of how it is to live with low levels of air, the simulation tool for chronical obstructive pulmonary disease, COPD, has been analyzed in order to develop it further. This in order to give the user a deeper understanding of how it can be living with breathing difficulties. There are a lot of different reasons for breathing difficulties, but when it comes to breathing difficulties caused by diseases, it is most commonly caused by diseases affecting the bronchi and the lungs. This project focuses on obstructive breathing problems, which means an increased air flow resistance in the bronchi. Asthma and COPD are the most common diseases.

    Through literature studies, interviews with people who has knowledge of the subject and people who has been diagnosed with asthma and COPD, the project resulted in three different parts and together they create a complete concept. The main part is a simulation tool, simulating breathing difficulties. In order to get a deeper understanding of how daily life can be and to get information of breathing difficulties an information sheet and scenarios have been created.

    The project results have created a more physiological and realistic basis for the empathy tool. Taking part of the experience of breathing with resistance, getting information about the meaning and demonstrating how daily life situations can be experienced by people with breathing difficulties will increase the knowledge for the user.

  • 13.
    Yasir, Irshad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics, Science, Mathematics and Engineering Education Research.
    A study of a stochastic differential equation based model for wireless channels2008Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    An autoregressive (AR) first order model is often used for modelling wireless channels. This is done in spite of the fact that a satisfactory physical explanation for this model has been missing. However, in the recent paper [Feng, Field and Haykin. 2007] derive a model in form of a first order stochastic differential equation (SDE) from a stochastic description of the scattered electric field. After discretizing this SDE, a physically motivated first order AR model is obtained.

1 - 13 of 13
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