liu.seSearch for publications in DiVA
Change search
Refine search result
123456 1 - 50 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Oldest first
  • Newest first
Select all
  • 1.
    Asklöf, Linn
    Linköping University, Department of Culture and Communication.
    Slöjan: om "av-slöjning": – En uppsats om unga, obeslöjade, svensk-muslimska kvinnors syn på slöjan och slöjdebatten2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This essay presents four not-/unveiled Swedish Muslim women's perceptions and experiences regarding the headscarf, the choice not to wear a headscarf, and the dominant understanding of the headscarf in Swedish society. Drawing on narratives of these women, this study aims to examine what it is that lies behind the choice not to wear the veil. Qualitative semi-structured interview was used as method for the collection of empirical data, and empirically guided thematic approach to the analysis of it. Moreover, set out from theoretical concepts of identity, classification, symbols, norms and social control, the obtained data is discussed.

    The participants in this study explains that they have never felt forced to wear the veil. They are of the opinion that one does not have to wear a headscarf in order to identify oneself as Muslim women. Islam, or ones level of religiosity, is not connected with a headscarf, rather, ones relationship as a Muslim is between that person and God. Moreover, the result indicates that the informants born in countries categorized as Muslim countries have been more affected by the Swedish secular society and its norms than those born in countries not categorized as Muslim countries. Nevertheless, they all fear potential rejection, negative sanctions and aggressions of society, causing them to stand by the decision not to wear a veil.            

  • 2.
    Pettersson, Thomas
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Analysis and implementation of the Smooth Discrete Element Method in AgX2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We encounter granular materials on a daily basis. We walk up a gravel path or we eat our breakfast cereals. When handling granular materials on an industrial scale it is important to do so efficiently, to avoid unnecessary energy losses, wear and tear. To help designing efficient tools for handling these materials engineers uses numerical simulations.

    This project investigates the difference between the two main approaches to simulation of granular materials, the Smooth- and Non-smooth Discrete Element Methods by implementing the Smooth method into AgX dynamics were the Non-smooth method already is implemented, and then setup and execute a range of experiments to investigate their differences.

    The investigation shows both advantages and weaknesses for both methods. The result of simulations with smooth discrete element method are more consistent than with the nonsmooth discrete element method with respect to choice of time step and other parameters that can be chosen for the simulation. Smooth discrete element method have problems when it comes to extreme situations.

    The relative simulation time for system as large as treated by this project (more than1000) can not be shown to depend on the size of the system.

  • 3.
    Andersson, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Modelling of Cranking Behaviour in Heavy Duty Truck Engines2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In modern heavy duty trucks the battery is a central component. Its traditional role as an energy source for engine cranking has been extended to include powering a number of elec- trical components on the truck, both during driving and during standstill. As a consequence of this it is important to know how much a battery in use has aged and lost in terms of ca- pacity and power output. The difficulty in measuring these factors on a battery in use causes problem, since heavy duty truck batteries are often replaced too early or too late, leading to unnecessary high replacement costs or truck standstill respectively.

    The overall goal of the effort, of which this thesis is a part, is to use a model of the cranking behaviour of a heavy duty truck engine, which depends on the battery condition, to estimate the ageing and wear of a heavy duty truck battery. This thesis proposes a modelling approach to model the components involved in engine cranking.

    In the thesis work, system identification is made of the systems forming part of the cranking of a heavy duty truck engine. These components are the starter battery, the starter motor and its electrical circuit and the internal combustion engine. Measurement data has been provided by Scania AB for the evaluation of the models. The data has been collected from crankings of a heavy duty diesel engine at different temperatures and battery charge levels. For every cranking lapse the battery voltage and current have been measured as well as the engine rotational speed.

    A starter battery model is developed and evaluated. The resulting battery model is then incorporated into two different engine cranking models, Model 1 and Model 2, including a starter motor model and an internal combustion engine model apart form the battery model. The two cranking models differ in several aspects and their differences and resulting evalu- ations are discussed.

    The battery model is concluded to be sufficiently accurate during model verification, however the two cranking models are not. Model 2 is verified as more correct in in its output than Model 1, but neither is sufficiently accurate for their purpose. The conclusion is drawn that the modelling approach is sound but development of Model 2 is needed before the model can be used in model-based condition estimation. 

  • 4.
    Tidholm, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Thermodynamic and electronic properties of niobium at finite temperatures2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Niobium (Nb) is a fascinating element, that when it is in a solid state has remarkable properties. This is believed to be a result of its electronic configuration that has partially filled 4d and 5s sub-shells. Nb has a melting temperature of 2750 K, a high strength at high temperature, and a good wear resistance. Because of these properties, Nb is used as material for components of rockets and jet engines, and for strengthening steel.

    In the phonon dispersion relations, Kohn anomalies are experimentally observed to weaken with increased temperature, which is related to the superconducting properties of Nb. I include anharmonicity when I calculate the thermodynamic properties of Nb and relate this to the electronic structure.

    In this thesis I show that anharmonicity can not be neglected when considering thermodynamic properties of Nb. I observe broadening in the electronic band structure with increasing temperature, correlated with the gradual weakening of the Kohn anomalies in the phonon dispersion relations. Kohn anomaly in the phonon dispersion relation can be observed at 300 K and is completely absent at 1200 K. The observation of the Kohn anomaly's disappearance in the calculations is of great importance because it cannot be repeated by approaches that do not include anharmonic effects, meaning that properties that are directly related to phonon dispersion, like elastic constants, can be calculated more accurately with this approach.

  • 5.
    Hallqvist, Joakim
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Faster Locking Differential Through Active Brake-Control2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When a vehicle with wheels aligned in pairs turn, the wheel traveling around the outside of the curve has to roll farther than the wheel on the inside. This means that some sort of device must must be used to allow the drive wheels to rotate at different speeds to prevent wear on the tires. This is usually a mechanical device where the input rotation controls the sum of the two output rotations, this is known as a differential. This solution however has some shortcomings, the biggest one is that the total amount of force that can be transferred between the tires and the road surface is limited by the tire with the least traction. In slippery conditions this can be a big problem since it only takes one wheel to lose traction in order to prevent the vehicle from accelerating. In this thesis a locking differential is used to overcome this shortcoming, this gives the driver the option to lock the shafts of the driving wheels together. This is done by pushing two cogwheels, one attached to each shaft, together. The aim of this thesis is to shorten the lock- and unlock-time of the locking differential by aligning the cogwheels using the service brakes and available sensors. The results were evaluated by implementing the software in a truck and doing test runs on Scanias test track. These tests showed that the system greatly improved both lock- and unlock-times but at cost of lower driver comfort. With additional work with some fine tuning of the system, the overall performance could probably be increased even more.

  • 6.
    Khajavizadeh, Lida
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Growth and structural characterization of ScN/CrN periodic and quasi-periodic superlattices for thermoelectric application2014Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The aim of this diploma work is the deposition and characterization of ScN/CrN superlattices with both periodic and quasi-periodic structures. ScN as semiconductor material with (2eV) band gap energy was selected due to its thermal and mechanical stability and its hardness. High resistivity against oxidation and high wear resistance were the reasons for choosing CrN as another candidate for the superlattices. The Rudin Shapiro structure was selected as quasi-periodic structure because of its more random structure.

    In this research both periodic and Rudin Shapiro as quasi-periodic structures have been deposited and investigated. The best optimized temperature for the deposition was 835°C and the selected periodic thickness was 6 nm for periodic structure with each ScN and CrN layers having each a thickness of 3 nm. The material ratio of Rudin Shapiro superlattices was kept the same as periodic samples. Evaluation of quasi-periodic and periodic superlattices was performed by X-ray diffraction measurements. Five peaks were recorded for superlattices measurement of periodic structure by diffraction. The envelope of the diffraction pattern represents two separated peaks in investigation of Rudin Shapiro investigation.

    The results of the X-ay measurements showed low quality of the superlattices for both deposited structures which suggest the need for further optimization of the deposition process or the use of other materials of superlattices.

  • 7.
    Lindehammar, Christian
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Mätdatasystem för testning av betongslipmaskiner2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work was made for HTC Sweden AB in Söderköping. The company develops and produces floor grinding systems. The task was to find suitable equipment for surveillance and to log data from the grinders. The interesting areas to measure were: temperature, current, revolutions per minute, wear on the tools and air moisture.

    The equipment was purchased and it consisted of sensors, data loggers and a data acquisition card. The project had a budget of 20 000 SEK. Software used was the demo version of LabVIEW and a full version of EasyView. To be able to log and survey data from the sensors a program was created in LabVIEW and a successful test run was made.

  • 8.
    Eriksson, Carl-Johan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wireless Weather Station for the detection of black ice on roads2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Keeping the Swedish roads safe during winter months is something that requires large resources and costs society a lot of money. The systems that provide information on road condition today are not enough. There are too few weather stations located around the road network to provide a good spatial resolution to those who decide if there is a need for ice- or snow removal on the roads. To provide a cost effective and completely wireless weather station that can be deployed regardless of access to power or wired communications is something that existed as a desire by the major contractors for the winter road maintenance in Sweden for a long time.

    A higher spatial resolution of weather conditions in the road network will make it possible to use more focused efforts where the road conditions are not good. This would result in reduced wear on the tools, less fuel consumption and reduced use of salt on the roadway resulting in economic gains and not least environmental benefits.

    Interviews and questionnaires were the basis for creating a base for a weather station of this kind. While working on weather station data, additional requests and ideas from people who are active in the industry emerged. This has led to the thesis work focused primarily on developing a new sensor system that completely contact-free from the road surface detect what is on the road surface when it comes to distinguish dry, wet or icy road surface.

    A complete sensor system has been developed that is placed in the roadway and which measures the temperature and uses a sensor that doesn't have any contact with the road surface to detect if the road surface is dry, wet, or if there is ice on it. The sensor system is battery powered and transmits data wirelessly from the road. This makes it possible to use multiple sensors in the roadway, thereby creating a sensor network that can determine what the conditions are at longer distances than in only one point.

  • 9.
    Håkman, Marcus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design.
    Tillberg, Max
    Linköping University, Department of Management and Engineering, Machine Design.
    Design och Kalibrering av mätrigg för Poly-V remmar2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Scania is one of the World greatest producers of trucks, busses and marine engines. The purpose of the master thesis has been to develop a new measuring rig for Poly-V belts, to better be able to verify wear, duration and elongation at different testing cycles. The rig shall do measurements following the SAE-J1459 standard and be able to perform on belts with length between 1000-3300 mm. In addition, the design must be made in accordance with safety regulations and ergonomic aspects.

    Measurement of Poly-V belts are carried out by straining the belt between to pulleys with a force of 100 N per crossbar.

    At the project start access was granted to an old measuring rig, which is no longer in use due to not fulfilling the requirements for the measuring procedure. However, it has been used to identify ergonomic and safety gaps. The development of new concepts has then been carried out with those gaps in mind.

    The design of the new measuring rig is developed by using proven product development methodology, which covers work from idée to completed product. That includes accordance with a pre-study in design methodology, a concept study which deals with a number of concepts, the selection of concepts and an analysis of the technical equipment used in the new design during the product design.

    The result of the thesis is a completed rig, delivered and ready to use. The rig is capable of measuring ribbed belt length between 1000-3300 mm and up to twelve ribs. Measurement process according to SAE-J1459 can be performed meanwhile the rig is designed with ergonomics and safety aspects. A user manual describing the use of equipment, risks and the actual measurement process step by step is also included with the rig.

    The report annexes a pre-study of ergonomic and safety, which has been written in the initial phase of the thesis. The pre-study has been used as a guide for the design of the new rig, taking into consideration the existing regulations from different acquis.

  • 10.
    Magnusson, Emelie
    Linköping University, Department of Management and Engineering, Mechanics.
    FE analysis and design of the mechanical connection in an osseointegrated prosthesis system2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis the connection between the two major parts of an osseointegrated prosthesis system for lower limb amputees has been investigated by finite element (FE) analysis. The prosthesis system is developed by Integrum and the current design consists of a fixture, which is integrated in the residual bone, an abutment that penetrates the skin and an abutment screw that holds the parts together. The connection between the fixture and the abutment has a hexagonal section and a press-fit section that together form the connection. Due to wear and fracture problems it is desired to improve the connection. A tapered connection could be an alternative and three different taper angles, the effect of the length of the taper and the smoothness of the outer edge of a tapered fixture have been investigated. The results show that the taper has potential to function well and that a longer connection will give lower stresses in the system, but further investigations are needed.

  • 11.
    Ceco, Ema
    Linköping University, Department of Electrical Engineering, Computer Vision.
    Image Analysis in the Field of Oil Contamination Monitoring2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Monitoring wear particles in lubricating oils allows specialists to evaluate thehealth and functionality of a mechanical system. The main analysis techniquesavailable today are manual particle analysis and automatic optical analysis. Man-ual particle analysis is effective and reliable since the analyst continuously seeswhat is being counted . The drawback is that the technique is quite time demand-ing and dependent of the skills of the analyst. Automatic optical particle countingconstitutes of a closed system not allowing for the objects counted to be observedin real-time. This has resulted in a number of sources of error for the instrument.In this thesis a new method for counting particles based on light microscopywith image analysis is proposed. It has proven to be a fast and effective methodthat eliminates the sources of error of the previously described methods. Thenew method correlates very well with manual analysis which is used as a refer-ence method throughout this study. Size estimation of particles and detectionof metallic particles has also shown to be possible with the current image analy-sis setup. With more advanced software and analysis instrumentation, the imageanalysis method could be further developed to a decision based machine allowingfor declarations about which wear mode is occurring in a mechanical system.

  • 12.
    Carlsson, Louise
    Linköping University, Department of Physics, Chemistry and Biology.
    Hierarchical Micro- and Nanostructured Superhydrophobic Surfaces to Reduce Fibrous Encapsulation of Pacemaker Leads: Nanotechnology in Practical Applications2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this master’s thesis was to, by the use of nanotechnology, improve material properties of the biomedical polymer Optim™, used as the insulation of pacemaker leads. Improved material properties are required to reduce the extent of fibrous encapsulation of the leads. Today, laser ablation is used to be able to remove the pacemaker lead because of the fibrous tissue, which can cause the lead to adhere to vascular structures. Consequently, the laser ablation results in risks of damaging cardiovascular structures. Moreover, improved material properties are needed to reduce the friction at the surface and enhance the wear resistance. Large wearing occurs between the lead and the titanium pacemaker shell as well as lead against lead and the wearing can result in a damaged insulation, which in turn might result in removal of the device.

    To achieve these improved material properties a hierarchically micro- and nanostructured and superhydrophobic surface was fabricated and to enhance the wear resistance, nanocomposites with 1 wt % and 5 wt % added hydroxyapatite nanoparticles were fabricated. The surface structures were fabricated via hot embossing and plasma treatment and were characterised with atomic force microscopy, environment scanning electron microscopy and with contact angle measurements. To evaluate the biological response to the surfaces, adsorption of radioisotope labelled human serum albumin proteins and adhesion of the human fibroblast cell line MRC-5 were studied.

    The results show that a superhydrophobic surface, with contact angle as high as 170.0 ± 0.4 °, can be fabricated via hierarchically micro- and nanostructures on an Optim™ surface. The fabricated surface is more protein resistant and cell resistant compared to a smooth surface. The nanocomposites fabricated, especially the one with 5 wt % nanoparticles added, show an enhanced abrasive wear resistance compared to Optim™ without added nanoparticles. In conclusion, a hierarchically micro- and nanostructured superhydrophobic surface of the pacemaker lead seems promising for reducing the extent of fibrous encapsulation and by fabricating a nanocomposite, the abrasive wear damage of the lead insulation can be reduced.

  • 13.
    Ingelsson, Urban
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Chang, Shih-Yen
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Larsson, Erik
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Cost Reduction of Wear-Out Monitoring by Measurement Point Selection2011In: The 11th Swedish System-on-Chip Conference, Varberg, Sweden, May 2-3, 2011, 2011Conference paper (Other academic)
    Abstract [en]

    Early failure rates have increased due to reduced feature dimensions and electromigration wear-out. Periodic delay measurements can be employed to estimate the state of wear-out. Including delay measurement sensors on-chip is costly. Therefore, a method is proposed to reduce the number of measurement points. The method identi?es wear-out sensitive interconnects and selects a small number of measurement points to target the identi?ed interconnects. The method is demonstrated on ISCAS85 benchmark ICs.

  • 14.
    Shah, Ghafoor
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Arslan, Saad
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Design of an in-field Embedded Test Controller2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electronic systems installed in their operation environments often require regular testing. The nanometer transistor size in new IC design technologies makes the electronic systems more vulnerable to defects. Due to certain reasons like wear out or over heating and difficulty to access systems in remote areas, in-field testing is vital. For in-field testing, embedded test controllers are more effective in terms of maintenance cost than external testers. For in-field testing, fault coverage, high memory requirements, test application time, flexibility and diagnosis are the main challenges.

    In this thesis, an Embedded Test Controller (ETC) is designed and implemented which provides flexible in-field testing and diagnostic capability with high fault coverage. The ETC has relatively low memory requirements for storing deterministic test data as compared to storing complete test vectors. The test patterns used by the ETC are stored separately for each component of the device under test, in system memory. The test patterns for each component are concatenated during test application according to a flexible test command. To address test application time (which corresponds to down time of the system), two different versions of the ETC are designed and implemented. These versions provide a trade off between test application time and hardware overhead. Hence, a system integrator can select which version to use depending on the cost factors at hand. The ETC can make use of an embedded CPU in the Device Under Test (DUT), for performing test on the DUT. For DUTs where no embedded CPU is available, there is the additional cost of a test specific CPU for the ETC. To access the DUT during the test application, the IEEE 1149.1 (JTAG) interface is used. The ETC generates test result that provides information of failing ICs and patterns.

    The designed and implemented versions of the ETC are validated through experimentations. An FPGA platform is used for experimental validation of the ETC versions. A set of tools are developed for automating the experimental setup. Performance and hardware cost of the ETC versions are evaluated using the ITC'02 benchmarks.

  • 15.
    Chang, Shih-Yen
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Placement of measurement points for wear-out prediction with regard to electromigration2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Nowadays, electronic systems are widely used in applications such as mobile phones, laptops, etc., but the electronic systems are not permanent and indestructible, so the reliability of an electronic system is a major concern. However, the lifetime of electronic systems are shorter than it was 40 years ago because the dimensions of wires are smaller due to the advanced manufacturing technologies.

     

    Electromigration is a wear-out mechanism which becomes an important issue, due to the fact that the reduced dimension of wires makes current density increase so that, the probability of failure due to electromigration is much higher than 40 years ago. Electromigration means the cross-section area of the wire decreases due to the movement of ions in high current density. The reduced cross-section area increases the resistance of the wire so that the delay of the wire is increasing as well. The whole system might fail when the delay is longer than the clock period.

     

    To predict electronic system failure caused by electromigration, a delay measurement circuit can be used as a predictor to give an early warning. However, the delay measurement circuit is expensive and not necessary for an electronic system to work correctly. Therefore, the purpose in this thesis is to minimize the number of measurement points. In order to minimize the number of measurement points, a method is developed to find the wear-out sensitive wires (WSWs) and determine where delay measurement circuits should be placed. Therefore, the measurement points are minimized and the cost of the system is also reduced.

  • 16.
    Pröstl, Susanne
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Attitudes and beliefs of students towards wearing bicycle helmets: A study carried out at Linköping University, Sweden2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The most common diagnoses after bicycle accidents are head injuries and fractures on arms and legs. At two of three injured cyclists, head injuries are the primary cause of death and bicycle helmets are a good protection against these injuries. Because the brain is very fragile, even a moderate hit can cause a serious injury. Arms and legs can often be treated, while brain damage could be a permanent disability. The main goal of this paper is to find out what makes students at Linköping University wear a bicycle helmet. The specific aim of this paper is to find out why students at Linköping University do not wear a bicycle helmet when they are cycling. The paper is divided into a literature review and a case study. The literature review delivers an insight into the road traffic safety system and the contributing factors that influence road traffic safety. It covers research analysis of experts about human behavior and gives an overview of relevant facts and figures concerning cycling within Sweden as well as within the European Union. The case study is a survey carried out at Linköping University. The method used is paper questionnaire with the target group of students at Linköping University. The result of the questionnaire is that more information regarding bicycle helmets and cycling as such, bicycle helmets for free or at least for reduced prices and to somehow change the attitudes towards bicycle helmets is important to increase the number of students wearing a bicycle helmet at Linköping University. As the most important reasons for not wearing a bicycle helmet, practical problems due to having no opportunity to fix the bicycle helmet secure to the bicycle, the fear of negative appearance and the discomfort of wearing a bicycle helmet have been mentioned. To increase the usage of bicycle helmets measures like increasing the awareness, reducing the helmet price or providing extra features with the helmet, based on the results of the literature review and the questionnaire, are suggested at the end of this paper.

  • 17.
    Lindbom, John
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Gustafsson, Mats
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Blomqvist, Göran
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Dahl, Andreas
    Division of Ergonomics and Aerosol Technology, Lund University, Lund, Sweden.
    Gudmundsson, Anders
    Division of Ergonomics and Aerosol Technology, Lund University, Lund, Sweden.
    Swietlicki, Erik
    Division of Nuclear Physics, Lund University, Lund, Sweden.
    Ljungman, Anders
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Wear particles generated from studded tires and pavement induces inflammatory reactions in mouse macrophage cells2007In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 20, no 6, 937-946 p.Article in journal (Refereed)
    Abstract [en]

    Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. These health risks are of increasing concern in society, and to protect public health, a clarification of the toxic properties of particles from different sources is of importance. Lately, wear particles generated from traffic have been recognized as a major contributing source to the overall particle load, especially in the Nordic countries where studded tires are used. The aim of this study was to further investigate and compare the ability to induce inflammatory mediators of different traffic-related wear particles collected from an urban street, a subway station, and studded tire-pavement wear. Inflammatory effects were measured as induction of nitric oxide (NO), IL-6, TNF-α, arachidonic acid (AA), and lipid peroxidation after exposure of the murine macrophage like cell line RAW 264.7. In addition, the redox potential of the particles was measured in a cell-free system. The results show that all particles tested induce IL-6, TNF-α, and NO, and those from the urban street were the most potent ones. In contrast, particles collected from a subway station were most potent to induce lipid peroxidation, A A release, and formation of ROS. Particles from studded tire-pavement wear, generated using a road simulator, were able to induce inflammatory cytokines, NO, lipid peroxidation, and ROS formation. Interestingly, particles generated from pavement containing granite as the main stone material were more potent than those generated from pavement containing quartzite as the main stone material.

  • 18.
    Lindbom, John
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Gustafsson, Mats
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Blomqvist, Göran
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Dahl, Andreas
    Division of Ergonomics and Aerosol Technology, Lund University, Lund, Sweden.
    Gudmundsson, Anders
    Division of Ergonomics and Aerosol Technology, Lund University, Lund, Sweden.
    Swietlicki, Erik
    Division of Nuclear Physics, Lund University, Lund, Sweden.
    Ljungman, Anders
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Exposure to wear particles generated from studded tires and pavement induces inflammatory cytokine release from human macrophages2006In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 19, no 4, 521-530 p.Article in journal (Refereed)
    Abstract [en]

    Health risks associated with exposure to airborne paniculate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. Lately, wear particles generated from traffic have been recognized to be a major contributing source to the overall particle load, especially in the Nordic countries were studded tires are used. In this work, we investigated the inflammatory effect of PM10 generated from the wear of studded tires on two different types of pavement. As comparison, we also investigated PM10 from a traffic-intensive street, a subway station, and diesel exhaust particles (DEP). Human monocyte-derived macrophages, nasal epithelial cells (RPMI 2650), and bronchial epithelial cells (BEAS-2B) were exposed to the different types of particles, and the secretion of IL-6, IL-8, IL-10, and TNF-α into the culture medium was measured. The results show a significant release of cytokines from macrophages after exposure for all types of particles. When particles generated from asphalt/granite pavement were compared to asphalt/quartzite pavement, the granite pavement had a significantly higher capacity to induce the release of cytokines. The granite pavement particles induced cytokine release at the same magnitude as the street particles did, which was higher than what particles from both a subway station and DEP did. Exposure of epithelial cells to PM 10 resulted in a significant increase of TNF-α secreted from BEAS-2B cells for all types of particles used (DEP was not tested), and the highest levels were induced by subway particles. None of the particle types were able to evoke detectable cytokine release from RPMI 2650 cells. The results indicate that PM10 generated by the wear of studded tires on the street surface is a large contributor to the cytokine-releasing ability of particles in traffic-intensive areas and that the type of pavement used is important for the level of this contribution. Furthermore, the airway inflammatory potential of wear particles from tires and pavement might be of a greater magnitude than that of DEP.

  • 19.
    Karlsson, Hanna L
    et al.
    Karolinska Institutet, Department of Biosciences and Nutrition at Novum, Unit for Analytical Toxicology, Huddinge, Stockholm, Sweden.
    Ljungman, Anders
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Lindbom, John
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Möller, Lennart
    Karolinska Institutet, Department of Biosciences and Nutrition at Novum, Unit for Analytical Toxicology, Huddinge, Stockholm, Sweden.
    Comparison of genotoxic and inflammatory effects of particles generated by wood combustion, a road simulator and collected from street and subway2006In: Toxicology Letters, ISSN 0378-4274, E-ISSN 1879-3169, Vol. 165, no 3, 203-211 p.Article in journal (Refereed)
    Abstract [en]

    The health effects of exposure to airborne particles are of increasing concern in society. In order to protect public health, a clarification of the toxic properties of particles from different sources is of importance. The aim of this study was to investigate and compare the genotoxicity and the ability to induce inflammatory mediators of nine different particle types from wood and pellets combustion, from tire–road wear and collected from an urban street and a subway station. The comet assay was used to assess genotoxicity after exposure of the human lung cell line A549. Inflammatory effects were measured as induction of IL-6, IL-8 and TNF-α after exposure of human macrophages. We found that all particles tested caused DNA damage and those from the subway caused more damage than the other particles (p < 0.001) likely due to redox-active iron. In contrast, particles collected from an urban street were most potent to induce inflammatory cytokines. Particles from tire–road wear collected using a road simulator were genotoxic and able to induce cytokines. Finally, more effective combustion of wood led to less emission of particles, but those emitted did not show less toxicity in this study.

  • 20.
    Strömberg, Niclas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Finite element Treatment of Thermoelastic Wear Problems1999In: IUTAM-Symposium on Unilaterial Multibody Dynamics,1998, 1999Conference paper (Other academic)
  • 21.
    Strömberg, Niclas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Finite Element Treatment of Thermoelastic Wear Problems1999In: Intl Symposium on Impact and Friction of Solids, Structures and Machines,1998, 1999Conference paper (Other academic)
  • 22. Dahl, Andreas
    et al.
    Gharibi, Arash
    Swietlicki, Erik
    Gudmundsson, Anders
    Bohgard, Mats
    Ljungman, Anders
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine.
    Blomqvist, Göran
    Gustafsson, Mats
    Traffic-generated emissions of ultrafine particles from pavement-tire interface2006In: Atmospheric Environment, ISSN 1352-2310, Vol. 40, no 7, 1314-1323 p.Article in journal (Refereed)
    Abstract [en]

    In a road simulator study, a significant source of sub-micrometer fine particles produced by the road-tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15-50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15-700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7×1011 and 3.2×10 12 particles vehicle-1 km-1 at speeds of 50 and 70 km h-1. This corresponds to between 0.1-1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road-tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road-tire interface may be a significant contributor to particle emissions from ultraclean vehicles. © 2005 Elsevier Ltd. All rights reserved.

  • 23.
    Eklund, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Novel ceramic Ti-Si-C nanocomposite coatings for electrical contact applications2007In: Surface Engineering, ISSN 0267-0844, Vol. 23, no 6, 406-411 p.Article in journal (Refereed)
    Abstract [en]

    Nanocomposite coatings consisting of TiC nanocrystallties embedded in an amorphous SiC matrix (nc-TiC/a-SiC) have been produced using magnetron sputtering from a Ti3SiC2 target onto electrical contact components at a temperature below 300°C. The as deposited nanocomposites were employed as electrical contact materials. Results show that when contacted against Ag, they exhibit somewhat higher contact resistance than Ag against Ag, while preventing welding and potentially minimising wear. This is due to an adequate resistivity coupled with beneficial mechanical properties. The design of the nanoscale materials produced coatings with a relatively high nanoindentation hardness of 20 GPa, but with a ductile deformation behaviour. The ductility is explained by rotation and gliding of nc-TiC grains in the matrix. Therefore, the nanocomposite material can minimise problems with wear and welding while retaining low contact resistance. Consequently, this type of novel coating with appropriate mechanical properties offers a solution to problems in many electrical applications. Moreover, the use of physically vapour deposited coatings is promoted in some previously relatively unexploited areas of electrical contact applications. © 2007 Institute of Materials, Minerals and Mining.

  • 24.
    Strömberg, Niclas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Finite Element Treatment of Two-dimensional Thermoelastic Wear Problems1999In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, Vol. 1777, 441-455 p.Article in journal (Other academic)
  • 25.
    Strömberg, Niclas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Finite element treatment of two-dimensional thermoelastic wear problems2000Other (Other (popular science, discussion, etc.))
  • 26.
    Sjöqvist, Carl-Henrik
    et al.
    Linköping University, Department of Management and Engineering, Assembly technology .
    Söderhielm, Oscar
    Linköping University, Department of Management and Engineering, Assembly technology . Linköping University, Department of Management and Engineering.
    Förstudie för automatisering av gjutgodsrensning2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis work has been performed at the Division of Assembly Technology at Linköping University for a period of ten weeks. The work is part of the project ProFlexA, which is a research project in collaboration between Linköping University, Lund University, and industrial partners such as Combi Wear Parts and Smålands Stålgjuteri AB.

    The casting process creates random incurred burrs and defects, which must be removed during a cleaning process to make sure that the cast can be sold. Automation has long been sought for the cleaning of castings due to, among other things, poor working conditions for staff, but this has proved difficult to implement with today's technology. Automation has for some time been available for more capital strong companies with large annual volumes, but for smaller companies with small-and medium-sized volumes, automation has not been an option.

    The goal of ProFlexA is to develop an automated cleaning cell aimed at small-and medium-sized volumes.

    The goal of the thesis is to do a pre study at ProFlexA’s partners on cleaning of castings, and develop concepts for automated cleaning of castings.

    By recording the process and cycle times, the cleaning of castings has been documented as it works today, and on this basis, information and statistics has been compiled. Conclusions have been drawn on preventive measures that may facilitate the development of an automated cleaning cell.  One of these is to change the geometry of the steel riser so that the resulting stub after removal by the pneumatic hammer is more controlled, and another measure is to relocate the location of the riser stub to an equal side of all the products. It is also important to prevent the defect caused by sand residues.

    Based on the documentation, it has been revealed that the product often is over-worked, which implies that an automated cell would provide a more even quality.

     

    Forces that occur in an operation of cleaning of castings have been measured. The results suggest that the forces in this context are 100 to 180 Newton, which indicates that the robot selected to the project, IRB 6660, is likely to be oversized. It can therefore be discussed if it is relevant with the current safety factor or if there is a reason to search for a smaller robot.

    Proposals have been prepared on concepts of automated cleaning of castings. These concepts show how a robotic cell can work when a single robot, compared with two robots are part of a cell, but also how it works with stationary tools compared with mobile tools.

    The design of a robotic cell should be sought in the objectives and needs of the specific company. A robotic cell with two robots is for example to be preferred when the need for efficiency is higher. Tools to a robotic cell is built in the simplest possible terms by a motor, a spindle and a tool, which is the option that seems to be a good choice in terms of whole and investment friendliness.

    For Combi Wear Parts a robotic cell with two robots is suitable, and for Smålands Stålgjuteri AB a robotic cell with a single robot is probably the best choice. For both of these solutions small and economic stationary tools would probably suit well.

  • 27.
    Edman Jönsson, Gustav
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Sputtring av Ti-Si-C-Ag beläggningar från sammansatta sputterkällor2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today gold is used as contact material on electric contacts for low current applications. Gold, however,has low wear resistance, is expensive and environmentally stressful to produce. An alternative contactmaterial to gold is nano composite Ti-Si-C-Ag deposited with DC-magnetron sputtering. Nanocomposite Ti-Si-C-Ag has so far been deposited by a compound Ti-Si-C sputter source with a separateAg source.

    In this work films have been deposited by three different compound Ti-Si-C-Ag sources with threedifferent carbon contents. The films have been deposited in two separate PVD systems: Oneconventional batch loaded and one sequential with a load-lock.

    The phase- and elemental composition of the films has been studied with XRD and EDX respectively.Thickness and microstructure have been analysed with SEM. Adhesion and resistivity has beenanalysed with Rockwell indentation and surface resistivity measurement with four point probe. Contactresistance has also been studied to a limited extent.

    The work shows that the increment of carbon content in the source yields more carbon rich films withlarger titanium carbide crystallites. The resistivity is increasing due to an increased amorphous phasebetween the crystallites but the contact resistance is decreasing due to a more ductile film.

  • 28.
    Vidar, Joachim
    et al.
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, Department of Management and Engineering.
    Mellstedt, Jonas
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, Department of Management and Engineering.
    Evaluation of Journal Bearings in Manual Transmissions2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is an evaluation of journal bearings in manual transmissions in automobiles. Today both journal- and needle bearings can be positioned into the gearboxes and in order to reduce the power loss developed by friction when a relative angular velocity arises, the right type of bearing must be chosen.

    In order to succeed, this work is aimed to develop a Matlab simulation model, which should be used as a tool in the design process of manual transmissions. The program development is later supposed to be followed by real tests of journal bearings, partly to cover things that can not be covered in the model but also to confirm how well the model reflects the reality. The absence of resources resulted in no performed real test and therefore was a comparison between theoretical-  and practical results not possible.

    Here the plain journal bearings in full film lubrication will have an disadvantage compared to the needle bearings regarding the power lost. To reduce the drag below the values of the needle bearings a modified journal bearing in the area of boundary lubrication with a very low coefficient of friction may be an option. But problems with wear under this condition could most certainly be devastating and must be further investigated with real tests.

    Out of a efficiency point of view the most suitable bearing position is the gear in the most frequently used area. Here it is assumed to be the 4th gear.

    A suitable journal bearing design should have a small sliding surface area in order to minimize the viscous drag. To achieve low friction the boundary lubricated area could be a good idea in cases when wear is not a critical factor. To longer the useful life nitrocarburizing is recommended, which both reduces wear and lower the coefficient of friction, in cases of asperites in contact. In order to work under the full film lubricated condition, with neglected wear, the sliding area needs to be large enough to create the required oil pressure.

  • 29.
    Larsson, Kerstin
    et al.
    Linköping University, Department of Management and Engineering. Linköping University, Department of Management and Engineering, Quality Technology and Management .
    Lundmarck, Josefina
    Linköping University, Department of Management and Engineering. Linköping University, Department of Management and Engineering, Quality Technology and Management .
    Målinriktad SPS - en utredning i processtabilitet2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     

    The statistical quality tool Statistical Process Control (SPC) was introduced at BT Products AB in Mjölby following the process of SPC implementation. The current process is a powder coating process where parts for powered trucks are painted black. The electrostatic powder coating is performed by four automatized robots and the desired layer thickness is 70 µm. The process has been evaluated from a quality characteristic, specified as the layer thickness, and special causes behind variation were identified. Data has been collected continuously from the process by measuring objects in the production, using a self-developed measurement template to receive comparable data. Statistical tools have been used to evaluate whether the data were reliable or not. A normal probability plot confirmed that the observations were normally distributed and a scatter plot established randomness. Autocorrelation was detected and the data had to be transformed, why the independent and reliable residuals were used in the subsequent analysis. Control charts were used to study the process over time, where individual x- and MR-charts detected large shifts in the process, while EWMA-charts detected small shifts. Alarms, trends and abnormal patterns were identified in these control charts, which led to the conclusion that the process could be considered out of control. The special causes behind this variation were assumed to stem from controllable factors and the work was therefore focused on identifying these special causes.

    Factors were listed in an Ishikawadiagram by a focus group and tested using mainly three different methods. Design of experiments was used to test a two factorial design, and single factors were tested by one-factor-tests. A sheet metal was painted in both test methods and the difference in layer thickness, dependent on chosen level of the factor, was studied. Other factors were logged parallel to the production. Additional observations were compared to the registered layer thickness on parts and the relation analysed using ANOVA- or correlation analyses. Examined factors from these tests were divided and categorized into Significant, Partially significant, Possibly significant and Not significant. Fluidisation and powder batch were identified as significant factors and thereby possible causes behind the identified variation. The fluidisation in one of the powder containers has at times been misbegotten, something that can explain the high level of autocorrelation and the low level of correlation between the robots. When testing the batches, four sacks from two different batches were used and a large difference in layer thickness was observed depending on powder origin. A high degree of wear of the partially significant factors, as injector nozzle, electrode and gun nozzle, could affect the result, but they likely have the largest impact when collaborating. By performing recommended actions, in an attempt to reduce the variation on the basis of the significant factors, the process once again can be studied and evaluated. Depending on the result, a stable process can be improved, alternatively, new sources behind variation identified.

     

  • 30.
    Lundström, Johan
    Linköping University, Department of Electrical Engineering.
    Road Roughness Etimation Using Available Vehicle Sensors2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Road conditions affect fuel efficiency and vehicle fatigue when driving heavy trucks. Information about traveled road conditions enable optimization of chassis configuration when driving, and logging of vehicle stress. Previous work on this topic focus mainly on tuning of active suspension parameters in the car industry. One conceivable application for heavy trucks is implementation of active chassis level control based on road conditions, with possible improvements in driving economy as result. Another is logging of usage conditions which helps explain vehicle faults caused by abnormal wear. This work examines the possibilities to use already on vehicle sensors for road roughness estimation. It also investigates what requirements existing signals must fulfill to ensure reliable estimates. Two methods for road roughness estimation are proposed using rear axle level sensor and a simple linear suspension system model.

  • 31.
    Zachrisson, Therese
    Linköping University, Department of Management and Engineering.
    The Human Factors Design of a Wearable Balance Belt2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Being able to keep your balance is something most of us take for granted. People with inner ear problems due to an accident or surgery or other dizziness have to live with this problem on a chronic basis. A balance prosthesis, worn around the torso, giving feedback about their upright position via tactile vibrators has been shown to help these people keep their balance.

    The goal and purpose for this thesis has been to conduct research on how to improve the existing balance prosthesis and adapt it to fit the user. The research has been conducted with the focus on human factors, meaning with the users’ experience as the premier aspect.

    To be able to reach a good solution with a prototype that would be an improvement compared to the existing device, a vest, several stages have been passed. At first twelve criteria were set up to establish human factors and hedonomic requirements. To fulfill these requirements, surveys with users were conducted. An extensive phase of prototyping and material research informed the design of a final concept.

    The final concept was a prototype balance belt that contains six vibrators, called tactors, and models of the other electronic components. The belt has an elastic band as a base and then a black spandex fabric that covers all components. A Velcro band and a buckle are used to open and close the belt. Finally the belt has a beige spandex cover that can be pulled on and off. This cover makes the belt easy to keep clean because the cover can be washed.

    The prototype is made in three different sizes so it can fit most people in the US population.

    In the near future it will be important to make an evaluation of the balance belt with users. It needs to be tested if the vibrators are possible to feel and how it feels to wear the belt for a longer time. An aid to help pulling the cover onto the belt also has to be developed because putting on the cover is a bit difficult right now.

  • 32.
    Gleisner, Jenny
    Linköping University, Department of Religion and Culture.
    En plats - En identitet2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    We live in a society where we are not bound to one place. We are encouraged to be mobile and constantly moving between different locations. The life in a convent is a contrast to this; nuns live at a specific place they are bounded to by vows and can not leave. The sisters in the convent of St. Birgitta, Pax Mariae have promised to stay at the same place and live by the rules of the convent. They live within the walls of the convent, an area with clear boarders. In this essay I analyse the meaning of a place, how the convent affects the nuns and their identity. The wall and the restricted area, inner- and outer attributes show where the nuns belong and characterize their life in the convent. The surrounding wall is a symbolic boarder to the nuns, but it also protects from impulses from the society and the outer world. The most evident influence the place has on the identities of the nuns is that they through vows become members of a camaraderie where they call each other sisters, changes their names and wear the same clothes. They become nuns, a ubiquitous identity. Regardless of whom they meet or of where they go, they will be seen as nuns.

  • 33.
    Gustafsson, Niklas
    Linköping University, Department of Electrical Engineering.
    The Use of Positioning Systems for Look-Ahead Control in Vehicles2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    The use of positioning systems in a vehicle is a research intensive field. In the first part of this thesis an increase in new applications is disclosed through a mapping of patent documents on how positioning systems can support adaptive cruise control, gear changing systems and engine control. Many ideas are presented and explained and the ideas are valued. Furthermore, a new method for selective catalytic reduction (SCR) control using a positioning system is introduced. It is concluded that look-ahead control, where the vehicle position in relation to the upcoming road section is utilized could give better fuel efficiency, lower emissions and less brake, transmission and engine wear.

    In the second part of this thesis a real time test platform for predictive speed control algorithms has been developed and tested in a real truck. Previously such algorithms could

    only be simulated. In this thesis an algorithm which utilizes model predictive control (MPC) and dynamic programming (DP) been implemented and evaluated. An initial comparative fuel test shows a reduction in fuel consumption when the MPC algorithm is used.

  • 34.
    Blomqvist, Michael
    et al.
    Linköping University, Department of Mechanical Engineering.
    Tunemar, Andreas
    Linköping University, Department of Mechanical Engineering.
    Modernisering av ångventil: Prestandaförbättring av spindelavtätning och hydraulisk servomotor2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    This thesis was preformed at Siemens Industrial Turbomachinery AB in Finspång. The work is to make modernizations of steam turbine valves. The first part of the project is to modernize stem packing with the purpose to find a more reliable and space-saving solution that is less sensitive to vibrations. The second part is to find an alternative solution for cup springs in servomotors. A new spring type is desirable to increase the lifetime, lower the wear on stem shafts and to make it more space-saving.

    To be able to perform the task efficiently and organized a method for systematic design has been used. This method has turned out to be quite useful tool in order to find new approaches to problems. Calculations of steam forces in a valve together with different types of box packing and springs have been done.

    The modernization of stem packing has resulted in a new type of box packing. The winnings of changing packing are lowered friction and need of maintenance. Two solutions of live load systems have been created. Both solutions minimize the need of maintenance and make the mount and dismount easier. An indication makes sure that a sufficient force is applied on the box packing.

    An analysis shows no alternative to replace the existing cup springs. The main goal was changed and modifications were made to improve the cup springs. The modifications results in a lowered wear and a significant increase of cup spring lifetime.

  • 35.
    Christensson, Pär
    et al.
    Linköping University, Department of Mechanical Engineering.
    Eriksson, Mikael
    Linköping University, Department of Mechanical Engineering.
    Spänningsanalys av axel-länkmekanism på borr-rigg2005Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This master thesis is intended to give an increased understanding of the stress state in an axle, which is assembled in one of Atlas Copco’s mountain drilling rigs. The main problems investigated were how the axle is affected when the bearing is worn, when the pretension is varied, and how to dimension the axle. Answers to these questions were found by using hand calculations, practical testing and with Finite Element analyzes. The dimensioning of the axle is currently based on the bending stress, but the author’s opinion is that the axle should be dimensioned considering the equivalent stress. Wear and pretension had large influence on the strain along the axle, but almost no influence on the shear stress and on the equivalent stress. Maximum equivalent stress occurs in the same place on the axle independently on wear and pretension, except for one case. This particular case is, however, not likely to occur. The maximum equivalent stress occurs inside the axle, at the hole which the pretension bolt goes through. This equivalent stress depends mostly on a shear stress concentration which occurs inside the axle. Theshear stress concentration was verified with a number of different FEM-models with various geometries, and with theory. The concentration depends on the geometry of the axle, and it occurs where the expansion bushings ends, but on the inside of the axle. The shear stress concentration is approximately two and a half time bigger than the stress on the outside of the axle. Finally a new design method is proposed which is based on the shear stress, that is recalculated into an equivalent stress.

  • 36.
    Haglund, Johan
    et al.
    Linköping University, Department of Management and Engineering.
    Gustafsson, Joel
    Linköping University, Department of Management and Engineering.
    Förslag till ombyggnation av klipp- och bockningsmaskin2008Independent thesis Basic level (university diploma), 10 points / 15 hpStudent thesis
    Abstract [en]

    This thesis work has been performed on request by SWT (Scandinavia WeldTech AB). SWT manufactures, develop and sell ready to assemble building systems for concrete rafter beam applications. The beams in this system consist of a u-beam that is welded to a flange. To be able to fill the beams with concrete there is holes in the beams top end. The holes are made in a “punching machine”.  These holes are cut out and the remaining steel piece is bent down in the u-beam. The problem today is that the machine only can make holes in beams with a height up to 340 mm. Now SWT wants a machine that can handle beams up to 500 mm high.

    Our task in this work was to make a feasibility study on what needs to be done to rebuild the machine. Besides the demand with higher beams we also looked at things to improve. Another task was to investigate the needs for cutting in beams made by thicker steel plates.

    In this work we used some of the theories described by David G. Ullman for the concept generation and evaluation. When generating the concepts we choose to make a concept of each subpart of the machine. Then we put the winning concepts together to form a final solution for the whole machine. When looking at the wear on the tools we could see that much could be done by making the control of the cutting column easier when adjusting the tool. To see what demands there were for cutting in thicker plates we had to come up with a theory for calculation off cutting and bending. Then we had to compare our theory with the reality, and that was done by measuring the pressure on the working cylinder when the machine was operating. Those results showed that our theory was working for 5 mm thickness but not for 4 mm thickness. There is however some uncertainness that makes our measured results not quite reliable for 4 mm steel.

    When it comes to the demand to manage higher beams we came to the conclusion that the best alternative is to manufacture a new frame. This is also suggested for the plates in the feeding unit. But we recommend that the existing cylinders and roof is used.

    For the problem on how to make the tool adjustments easier we came up with two solutions. The alternative with manual adjusting and assembly demands a reconstruction of the hydraulic system so that its functions meets the demands that are needed to realize the proposed solution. The advantage with this proposition is that the operator always has the possibility to affect the position of the tools so that the right cutting column is received. Our other suggestion is to install permanent steering guiding so the lower die gets in right position when mounting it. This proposal does not mean any bigger reconstruction but it does not make it possible to adjust the position of the cutting tool. To work proper both our solutions demands that the lower dies is modified.

    To make the mounting of the upper die easier we came up with two solutions that in short terms means that the die is held up before mounting. This means that the operator can have both his hands free when tighten the bolts.

    If thicker plate should be cut it will lead to large reconstructions of the hydraulic system with new cylinders and more. This due to the maximum pressing force that the machine is capable of is too small. But for a small change in thickness it might be enough to lower the force by reducing the friction in terms of better lubrication and modified tools.

  • 37.
    Muhic, Dino
    Linköping University, The Department of Physics, Chemistry and Biology. Linköping University, The Department of Physics, Chemistry and Biology.
    High consistency refining of mechanical pulps during varying refining conditions: High consistency refiner conditions effect on pulp quality2008Independent thesis Advanced level (degree of Master), 20 points / 30 hpStudent thesis
    Abstract [en]

     

    The correlation between pulp properties and operating conditions in high consistency (HC) refiners at Holmen Paper AB were studied. Two types of HC refiners were investigated: the Andritz RTS refiner at the Hallstavik Mill and the Sprout-Bauer Twin 60 refiner at the Braviken Mill. The objective of the study was to clarify the relationship between the pulp properties and refining conditions such as electrical energy input, housing- and feed- pressure and plate wear in high consistency refining.

    The results of this project show that worn segments reduce the operating energy maximum input and the pulp and handsheet properties in negative aspects such as lower tensile- and tear index, and shorter average fibre length. Energy input is an important factor in the refining process and influence Canadian Standard Freeness and the tensile index as evident from the probability residuals. Housing pressure and feed pressure influence the pulp quality and should be adjusted in order to optimise the refining process, although the effect is not as great as for energy input or plate wear.

    The results of the study indicate that Braviken Mill is operating at its optimum for the parameters measured in this project. Hallstaviks goal, to avoid fibre shortening and to obtain better tensile index, can be reached by making slight changes in pressure condition.

     

  • 38.
    Voxberg, Joel
    et al.
    Linköping University, Department of Management and Engineering.
    Persson, Johan
    Linköping University, Department of Management and Engineering.
    Design of a Pivotally Tool Holder2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    Ljunghäll AB in Södra Vi has many industrial robots in their casting production. These

    robots have a tendency to wear out. The purpose with this thesis was to design a toolholder

    that was able flip to a 90 degree angle to get a more flexible production but also to

    lessen the wear on the robot.

    Parts of David G. Ullman and Ulf Liedholm’s design processes was used as a base for

    the solutions and the conceptual design.

    A number of concepts where made and one of them evaluated to be a refined concept.

    The result became a tool-holder that used an air-motor and two spur gears to rotate the

    plate where the tool is mounted to a 90 degree angle. According to the calculations that was

    made, both by hand and by the computer program COSMOS, the concept should work

    in practice. A prototype ought to be made to guarantee the function of the concept.

  • 39.
    Marciszko, Fredrik
    Linköping University, Department of Electrical Engineering.
    Torque Sensor based Powertrain Control2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The transmission is probably the drivetrain component with the greatest impact on driveability of an automatic transmission equipped vehicle. Since the driver only has an indirect influence on the gear shift timing, except for situations like kick-down accelerations, it is desirable to improve shift quality as perceived by the driver. However, improving shift quality is a problem normally diametrically opposed to minimizing transmission clutch energy dissipation. The latter has a great impact on transmission lifetime, and has to be defined and taken into consideration along with the notion of shift quality. The main focus of this thesis is the modeling of a drivetrain of an automatic transmission vehicle, and the implementation in MatLab/Simulink, including the first to second gear upshift. The resulting plant based on the derived equations is validated using data from a test vehicle equipped with a torque sensor located at the transmission output shaft. The shaft torque is more or less proportional to the driveline jerk, and hence of great interest for control purposes. Control strategies are discussed and a PID controller structure is developed to control the first to second gear upshift, as opposed to the traditional open-loop upshift control. Furthermore, the proposed controller structure uses the transmission output torque and the differential speed of the engaging clutch as inputs, to control the clutch pressure and the engine output torque, respectively. The structure is unsophisticated and transparent compared to other approaches, but shows great theoretical results in terms of improved shift quality and decreased clutch wear.

  • 40.
    Dyrendahl, Johan
    et al.
    Linköping University, Department of Management and Economics.
    Karlsson, Sophia
    Linköping University, Department of Management and Economics.
    Immateriella värden & design -eller ”Det skall tåla ögats slitage”2002Independent thesis Advanced level (degree of Magister)Student thesis
    Abstract [en]

    Background: In the competition for the consumer of tomorrow it is not likely going to be enough to deliver material value. Companies will have to offer immaterial values through experiences. One way of doing this is by the design of the product. The relevance is emphasised further as there is little research available regarding immaterial value creation and design.

    Purpose: The purpose of the thesis is to contribute with understanding for how design can add immaterial value to a product.

    Research method: Initially a number of concepts were constructed out of theories originating in widely different theoretical fields. These concept were then evolved by interpretation of a number of interviews with relevant actors.

    Result: The immaterial values that are added to a piece of furniture by design can be understood with the help of main categories: aesthetic and social value. The creationof these values can to a large extent be understood in the terms of a social construction carried by a number of actors in a value configuration. A story is constructed which give the piece of furniture value. Knowledge is of great importance for the value appreciation of the consumer/user. The result should have great generality as it is of a concept creation quality.

  • 41.
    Bildsten, Louise
    et al.
    Linköping University, Department of Management and Economics.
    Sjölund, Annika
    Linköping University, Department of Management and Economics.
    Export of quality clothing at a men's wear manufacturer -a study of market strategies at the House of Monatic in South Africa2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    South Africa, as many of the countries on the African continent, has for a long time been discriminated against when it comes to export of clothing and textiles. The trade regulations are now getting more favorable and the US and European markets are becoming more open for exports from the African continent.

    We came in contact with the House of Monatic, which is a manufacturer of high quality men’s wear clothing in South Africa, and found that they were interested in us doing an export analysis of the company. The House of Monatic is an old colonial company founded in 1906 with over 1000 employees. The head office is situated in Cape Town, South Africa. Monatic manufactures licensed brands such as Yves Saint-Laurent as well as their own brands. At present the company is exporting to countries on the African continent, United Kingdom, Ireland and the United States. The thesis was mostly carried out at the House of Monatic in Cape Town where we stayed for three months. The method was to interview all the managers at the company to find out how the export management is run today and through theories find alternative exports strategies and how to improve the company’s current strategies. We also made a customer survey, which we sent out to Monatic’s customers to see

    The end of apartheid in 1994 opened the borders not only for further exports but also for imports from overseas countries. This made Monatic’s domestic market share shrink and expanding through exports to new international markets became inevitable. Because the trade regulations are becoming more favorable we believe the international market is where profits can be found, especially on the US market. A risk when exporting is that profitability can be dependent on the exchange rates between currencies. As a solution to this problem Monatic could convince its international customers to do business in the South African currency, Rand. Monatic is currently establishing contacts in the US where they are setting up a new sales office. Monatic is going to introduce one of their own brands by letting a customer called Nordstrom sell it.

    We think this is wise to sneak into the market and to not undertake large marketing campaigns, which could prove to be too costly. We believe it is risky for Monatic to enter several markets at the same time and that Monatic should concentrate on positioning itself on the US market at the moment. But we think it is smart to establish new contacts on other markets so that Monatic is ready when the opportunities come. We believe the Sub Saharan market has some potential that is worth further investigation. The UK market seems to have stagnated at the moment and we think it will become more profitable when the economy in Europe has recuperated. In the meantime it is best not to make to much investments but to harvest the profits that can be gained. There seem to be confusion about weather Monatic should focus on being a designer house or a manufacturer. It is difficult to combine the big bulk customers with boutique customers in the same production line.

    Many of the customers wants improved design according to a customer survey we conducted. We also believe that the customers need to be organized in a classification system depending on volume and profitability. This would help Monatic to decide on how to distribute its limited resources. IT is becoming more and more frequently used among Monatic’s business partners. To not risking being pushed out of the market it is important to be ahead of competitors. By introducing an online order system and a product tracking system at the home page Monatic would decrease the workload of the sales staff. Furthermore it would make it easier for customers and Monatic would gain more competitive advantage by this facility. We also believe that by establishing their own shops in South Africa, Monatic’s brand would be strengthened and become more competitive on the domestic market. A Monatic shop would give an entire atmosphere and service to the customer that would

  • 42.
    Stigermark, Johan
    et al.
    Linköping University, Department of Management and Engineering.
    Åkesson, Tommie
    Linköping University, Department of Management and Engineering.
    Effektiv provningsmetodik för växelföringsdamasker2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    Completed durability testing of gearshift gaiters at Kongsberg Automotive in Mullsjö, is sometimes leading to discussions regarding whether or not a gaiter is supposed to be a pass or a fail. That is because the current pass/fail-criterion are a bit vague. A durability test takes around 4-5 weeks to complete which is a long time if the tested material does not pass the test and a new material has to be tested instead. Stricter pass/fail-criterions and a faster testing method for the materials are therefore desired.

    In order to develop a durable pass/fail criteria, seven already judged gaiters were chosen. Every one of the gaiters was put through detailed analysis, after which there were a new assessment of the gaiters. We let the development department control the gaiters once more and give a new verdict. On the basis of the reiteration and divergency of these results the source of error in the earlier results could be tracked. A proposition of new pass/fail criteria where made based on these results.

    In order to develop a testing device for gear shift gaiters, the first step was choosing a selection of interesting damage cases. A few gaiters with this kind of wear were then analyzed under realistic conditions so that angle changes and movements in the creases were measured. With the aid of these measurements we were able to develop a solution for replication of the damages under more controlled circumstances. After perfecting the solution, blueprints were made by drawing a model in the CAD program Pro-Engineer. These blueprints were given to the production workshop at Linköpings University so that a prototype could be made.

  • 43.
    Gambino, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Titanium vacancy diffusion in TiN via non-equilibrium ab initio molecular dynamics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transition metal nitrides (TMNs) refractory ceramic materials are  widely employed as wear-resistant protective coatings in industrial machining as well as diffusion barriers inhibiting migration of metal impurities from the interconnects to the semiconducting region of electronic devices. TiN is the prototype of this class of materials and the most studied among TMNs. However, also for this system, a complete picture of the migration processes occurring at the atomic scale is still lacking. In this work I investigate the stability of Ti vacancy configurations and corresponding migration rates in TiN by means of density functional theory (DFT) calculations and ab-initio molecular dynamics simulations (AIMD). DFT calculations show that Ti vacancies tend to stay isolated because of repulsive interaction which decreases as the inverse of the distance between the vacancies.The equilibrium jump rate of single Ti vacancies in TiN is extrapolated temperature as a function of temperature from the results of non-equilibrium AIMD simulations accelerated by a bias force field according to the color diffusion algorithm. For each force field and, the jump occurrence times are fitted with the two parameters Gamma distribution in order to obtain the non equilibrium jump rate with the corresponding uncertainty. Extrapolated equilibrium values show an Arrhenius-like behavior, with activation energy Ea= (3.78 ± 0.28)eV and attempt frequency A = 4.45 (x3.6±1) x 1014 s-1.

  • 44.
    Thornblad, Johan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Drivetrain Modelling and Clutch Temperature Estimation in Heavy Duty Trucks2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An existing drivetrain model with clutch temperature dynamics has been used to simulate the behaviour of a heavy duty truck. During the implementation of the model in MATLAB/Simulink modularity and simplicity was greatly emphasized. This was done in order to facilitate the use of the model in various applications as well as making it easy to understand. The main contributions of the thesis is however the adaptation of a clutch temperature and wear observer for use in an on-line application in the gearbox management system (GMS). The process of taking the observer from an off-line simulation environment to running on-line includes taking into consideration the configuration and limitations of the GMS as well as adapting the interface of the observer. Concretely this means dealing with the limitations of the available data types in the GMS, compensating for the effect of biased measurements as well as accounting for the different dynamics of the sensor-types used in the clutch.In a simulation environment the performance of the adapted observer has been studied and its ability to compensate for heat expansion and wear in the clutch shown.

  • 45.
    Beck-Norén, Gustav
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Cross-platform Development for Wearable Devices2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The market for wearable devices is continuously growing and has seen an in- crease in interest and demand this past year, specifically smartwatch devices. With several big players entering and trying to take place in the market the number of devices and platforms grow. This leads to device and software fragmentation like the one seen in the world of smartphones. In this paper I discuss and compare the two smartwatch platforms Android Wear and Apple Watch in terms of possibilities, limitations and differences. Research is done to find cross-platform development possibilities for these platforms. Extensive theoretical background of both APIs is researched and presented. An app for both smartwatch platforms is developed with integration of the WebSocket protocol to function as a remote control for a Video-On-Demand web service. This is done to showcase the cross-platform possibilities and differences of the platforms. As a result the biggest differences are out- lined and a conclusion is made that cross-platform development for these platforms can be challenging but is possible on certain levels. 

  • 46.
    Sundqvist, Jacob
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Ekskog, Jonas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Victim Localization Using RF-signals and Multiple Agents in Search & Rescue2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A common problem in existing Search And Rescue (SAR) systems is that they must be activated by the missing person in order to work. This requires an awareness of the the risk of becoming distressed, which in many cases is not feasible. Furthermore, most of the localization systems require specialized hardware.In this thesis, the victim is assumed to wear a cellphone that could be located using readily available consumer electronics. A method of estimating the position of a transmitter, given radio signal measurements at different locations, is developed and verified with real and simulated data. A proof-of-concept system is built in which several users can jointly collect received signal strength data at different locations using mobile phones. The system analyzes the data in real-time and guides the users in the search by estimating the origin of the signal.An outdoor field test is conducted in which the searchers using the system are able to locate the hidden target phone without prior knowledge regarding the position. We are able to localize the victim with an accuracy of 10-20 meters in a timely manner using android smartphones. This shows the potential of a similar system in \abbrSAR scenarios. However, more work is needed to make the system viable in real scenarios and to remove some of the delimitations of the current implementation.

  • 47.
    Martinsson, Joel
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Controlled Start Transmission Wet Clutch Temperature Modeling and Application2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Controlled Start Transmissions (CST) can be described as a mechanical transmission combined with a wet clutch for controlled torque output. CST:s are commonly used to start up heavy loads for example mining conveyors. Several CST:s can work together to share the load. The transferred torque is controlled by a hydraulic wet clutch which is a proven technology for high torque transfer and low wear. This thesis is a part of a project to increase the knowledge and improve the CST design and control performance. The heat generation in the wet clutch is the focus of this thesis. Literature review shows that most research is done in order to get high accuracy for smaller clutches and most of the high torque engagements have very short transients.Models for the CST clutch heat generation together with thermal behavior have been developed and investigated. This includes a temperature model together with a kinetic model of the gearbox and a clutch torque model. Validation of separate model components and sensitivity analysis of the parameters are made. The developed model is then analyzed by comparing measurements from a commission site and simulations to get an idea of how much heat is generated.

  • 48.
    Karlsson, Lina
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Sensorless Control of a Hybrid Stepper Motor2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electrical drives are widely used in today’s society. They can be found in bothhousehold products and in the industry. One application where electrical drivesare used is in robots for mowing lawns. In the studied robots the motors in theelectrical drives used for propulsion are Brush Less Direct Current motors, BLDCmotors.The BLDC-motor has its maximum torque at high speeds and thereforea gearbox is needed. The gearbox is space consuming, add costs and consists ofmechanical parts that wear during use. Of interest is therefore to investigate ifthere are other electrical drives which can be used for propulsion.A motor who has its maximum torque at low speeds is the Stepper motor, andtherefore it is of interest to investigate if a stepper motor could replace the BLDCmotor.A drawback with the stepper motor is that it always consumes maximumcurrent and therefore a current controller is beneficial. Together with currentcontrol, speed control is needed to make the robot run at desired speed. To beable to perform an accurate current and speed control feedback from the motor isneeded. Information about the rotor angle and velocity can be used for the speedcontrol and the load angle can be used for the current control since the current isproportional to the load torque.To estimate the rotor angle and velocity a model has been developed. Themodel is based on fundamental electrical and mechanical equations and neglectsthe current and position dependence of the inductance and flux linkage. To completethe model three motor parameters, the maximum detent torque Tdm, themaximum flux linkage  m and the friction constant B was determined. Parameterdetermination was done by linear regression and by using an Extended KalmanFilter, EKF. The result of the parameter determination were Tdm = 0.2152 Nm, m = -0.002854 Vs/rad and B = 0.01186 Nms/rad.The model is used in an EKF to estimate the rotor angle and angular velocity.The result of the implemented EKF seems promising. When making the rotortake a step in velocity from 3.927 rad/s to 7.85 rad/s the EKF estimates the stateswith only a small bias: 0.02 rad for the angle, 0.3 rad/s for the velocity, 0.005 Afor phase a current and 0.0004 A for phase b current.To estimate the load angle the Sliding Discrete Fourier Transform is used. Theexpected relation between the load torque and load angle is sinusoidal. The loadangle is calculated from data where the external load is between 0-2.5 Nm. Inthat area the load angle shows the expected sinusoidal appearance and the loadangle is in the area between 0.1 and 0.45 rad. At 3 Nm the rotor stalls and it isshown that the load angle varies between 0 and 2 rad when the rotor is stalled.

  • 49.
    Griph, Sofie
    Linköping University, Department of Electrical Engineering, Automatic Control.
    Electric Motor Controlled Joint Simulator2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Tightening systems are used in several industries, including assembly in the auto- motive industry and installation of computer hardware. Both the company mak- ing the tools and the customers need to know the performance of the tightening system to ensure that the screw joints tighten as desired. This can be done using a test joint system.

    High demands on safety as well as fast assembly speeds, puts high demands on the test equipment. The problem with the existing test joints is that they are hard to do repeatable tests on. The most common test joints are constructed us- ing mechanic or hydraulic systems. The mechanical systems have problems with wear of screws, changes in lubrication etc., while the hydraulic systems some- times are too slow.

    This master’s thesis is a study of whether it would be possible to construct a test joint using an electric motor. The electric motor together with a controller should simulate a screw joint so that the tool would perceive it as a real one. All investigation has been performed by system modeling and simulations in MATLAB. Four different control structures have been evaluated: a PID controller, one combined controller which uses feedforward from reference as well as distur- bance, one which is based on the same structure as the second but with an added inner current loop and the last one is an LQ controller.

    The conclusion is that it is possible to make a test joint using an electric motor and that the LQ controller seems to be the best choice. To prove the result, a few more aspects could be investigated more closely. One is to add a dynamic model of the tool, now only the reference to the tool is used. Another is to implement it on hardware. 

  • 50.
    Westberg, Emilie
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Qualitative and Quantitative Analysis of Biodiesel Deposits Formed on a Hot Metal Surface2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis aims to investigate the formation of deposits from thermally degraded biodiesel on a hot metal surface under the influence of sodium or copper contaminations. Biodiesel or Fatty Acid Methyl Esters (FAMEs) is a widely utilized biofuel with the potential to replace fossil fuels, however, issues regarding the thermal and oxidative stability prevent the progress of biodiesel for utilization as vehicle fuel. The thermal degradation of biodiesel causes formation of deposits often occurring in the fuel injectors, which could result in reduced engine efficiency, increased emissions and engine wear. However, still have no standard method for evaluation of a fuels’ tendency to form deposits been developed. In this study biodiesel deposits have been formed on aluminum test tubes utilizing a Hot Liquid Process Simulator (HLPS), an instrument based on the principle of the Jet Fuel Thermal Oxidation Tester (JFTOT). Quantitative and qualitative analyses have been made utilizing an array of techniques including Scanning Electron Microscopy (SEM), Gas Chromatography Mass Spectrometry (GCMS) and Attenuated Total Reflectance Fourier Transform Infrared Spectrometry (ATR-FTIR). A multi-factorial trial investigating the effects of sodium hydroxide and copper contaminations at trace levels and the impact of a paraffin inhibitor copolymer additive on three different FAME products, two derived from rapeseed oil and one from waste cooking oil as well as a biodiesel blend with mineral diesel, was conducted.The results exhibited that FAMEs are the major precursor to deposit formation in diesel fuel. The SEM analyses exploited the nature of FAME deposits forming porous structures on hot metal surfaces. Sodium hydroxide proved to participate in the deposit formation by forming carboxylic salts. However, the copper contamination exhibited no enhancing effect on the deposits, possibly due to interference of the blank oil in which copper was received. The paraffin inhibitor functioning as a crystal modifier had significant reducing effect on the deposit formation for all biodiesel samples except for the FAME product derived from waste cooking oil. Further studies are needed in order to investigate the influence of glycerin and water residues to the biodiesel deposit formation. Mechanisms involving oxidative or thermal peroxide formation, polymerization and disintegration have been suggested as degradation pathways for biodiesel. The involvement of oxidation intermediates, peroxides, was confirmed by the experiments performed in this thesis. However, the mechanisms of biodiesel deposit formation are complex and hard to study as the deposits are seemingly insoluble. Nevertheless, ATR-FTIR in combination with JFTOT-processing has potential as standard method for evaluation of deposit forming tendencies of biodiesel.

123456 1 - 50 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf