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  • 1.
    Aasberg, Pål
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energilager i en överdimensioneradvindkraftspark: En linjäroptimering av batterilager i kombination medintermittenta förnybara energikällor2022Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A linear optimization has been made to examine the economic viabilityof incorporating battery storage in a wind farm in Sweden. The studyexamines a future wind farm with 10 10 MW turbines. An orographicmapping with height differences and vegetation has been used incombination with measured wind data with IEC-rated anemometersand wind direction sensors between 1997 and 2017 to create asimulated production in the windPRO software. This effect, togetherwith hourly prices from 2021 from Nord pool in SE1, SE2, SE3, SE4and in Estonia, has been used in a linear optimization in Matlab to findthe battery capacity that generates the most revenue. 3 Scenarios areinvestigated where scenario 1 is a wind farm without battery storagewhere all electricity produced is sold directly at the current price.Scenario 2 also lacks battery storage and has a power limit of 75 MWat the transformer whilst the farm still produces 100 MW. Scenario 3has a power limit of 75 MW at the transformer and the possibility ofbattery storage.

  • 2.
    Abas, Naeem
    et al.
    University of Gujrat, Hafiz Hayat Campus, Pakistan.
    Kalair, Ali Raza
    COMSATS University Islamabad, Pakistan.
    Seyedmahmoudian, Mehdi
    Swinburne University, Australia.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Campana, Pietro Elia
    Mälardalen University, Sweden.
    Khan, Nasrullah
    COMSATS University Islamabad, Pakistan.
    Dynamic simulation of solar water heating system using supercritical CO2 as mediating fluid under sub-zero temperature conditions2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 161, article id 114152Article in journal (Refereed)
    Abstract [en]

    CO2 is becoming increasingly important as a mediating fluid, and simulation studies are indispensable for corresponding developments. In this study, a simulation-based performance investigation of a solar water heating system using CO2 as a mediating fluid under sub-zero temperature condition is performed using the TRNSYS (R) software. The maximum performance is achieved at a solar savings fraction of 0.83 during July. The as lowest solar savingss fraction of 0.41 is obtained during December. The annual heat production of the proposed system under Fargo climate is estimated to be about 2545 kWh. An evacuated glass tube solar collector is designed, fabricated and tested for various climate conditions. Moreover, a detailed comparison of the system's performance at sub/supercritical and supercritical pressures shows that the annual heat transfer efficiency of the modeled system is 10% higher at supercritical pressure than at sub/supercritical pressures. This result can be attributd to the strong convection flow of CO2 caused by density inhomogeneities, especially in the near critical region. This condition resuls in high heat transfer rates.

  • 3.
    Abbas, Asad
    Karlstad University, Faculty of Technology and Science.
    Flow sheeting software as a tool when teaching Chemical Engineering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to design different chemical processes by using flow sheeting software and to show the usefulness of flow sheeting software as an educational tool. The industries studied are hydrogen, sulfur, nitric acid and ethylene glycol production and a model of drying technique is also included. Firstly, there is an introduction of chemcad as a tool when teaching chemical processes and explanation of each industry which is selected to design. Various production methods for each product are explained and the advantages of the method which is selected to design the chemical flow sheet are discussed. There is also an introduction of the industrial uses of these products formed in Pakistan. The models are designed by using different reactors, heat exchangers, pumps, mixers, boilers and distillation column. The models are designed based upon data taken from literature. The temperature and pressure values are in good agreement with data mentioned in literature. The material balance shown by Chemcad is quite different from data mentioned in literature. Some changes in thermodynamic properties of components in Chemcad software might lead to better agreement between the Chemcad models and literature data. It is not possible to use catalyst in Chemcad to increase the rate of reaction. One possibility is to introduce new components. It is good to use equilibrium reactor when it is required to convert the given component into respective products provided that either conversion of the equilibrium constant are known. It is difficult to study the hidden critical assumptions built in the model when using Gibb’s reactor, as a result there is a deviation in behavior from the system described in the literature. Gibb’s reactor is useful when neither conversion ratio nor equilibrium constant is known.

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    Flow sheeting software
  • 4.
    Abbas, Azhar
    Karlstad University, Faculty of Technology and Science.
    GPIB- kommunikation och PID reglering med LabVIEW2009Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    LabVIEW ger en snabb och enkel tillgång till att styra instrument och en mycket stor databas med drivrutiner för DAQ-kort och olika datorgränssnitt (GPIB, serie, osv.).

    Många instrument och datorer kan anslutas till GPIB-bussen.  Detta kan ge en praktisk modell för utveckling av instrumentets styrprogram i LabVIEW med hjälp av GPIB-gränssnittet.

    Ett program i LabVIEW 8.2 med hjälp av GPIB-bussen kan kopplas till t.ex. multimetern (HP-34401A) för att mäta och visa multimeters noggrannhet. Men på grund av fel i drivrutiner för GPIB-gränssnittet kunde jag inte köra programmet med GPIB-bussen.

    Genom att använda LabVIEW 8.2 med hjälp av DAQ-kort kan en PID-regleringsalgoritm simuleras. PID konstrueras med virtuella instrument som innehåller alla nödvändiga komponenter och utrustning som krävs för att reglera någon linjär eller olinjär process exempelvis att nivåreglera två tankar i serie. Här stöter vi på alla de grundläggande regulatorer och får möjlighet att bygga PID med LabVIEW på ett enkelt sätt. Det finns två metoder för att bygga PID. Den första är med matematiska funktioner och den andra är med ’’Simulations functions control’’. Arbetet visar att bägge metoderna fungerar bra för att lösa uppgiften jämfört med färdiga PID-controls på LabVIEW.

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  • 5.
    Abbas, Husam
    Karlstad University.
    Comparative analysis of different pyrolysis techniques by using kraft lignin: Jämförelse mellan olika pyrolys metoder2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a comparison analysis between various pyrolysis techniques performed on kraft lignin. Numerous literature studies of pyrolysis techniques performed on kraft lignin are reviewed and analysed where different operation temperatures, catalysts and different heating methods are used to pyrolyze kraft lignin. Based on the collected data from the reviewed literature, calculations are performed to determine energy efficiency of each pyrolysis technique. The energy efficiencies are used to establish a comparison between various pyrolysis techniques. Energy efficiencies of all pyrolysis techniques are determined by using series of equations.

    Dissimilarities of products composition are investigated between various pyrolysis techniques. Environmental impacts caused by lignin pyrolysis are reviewed and discussed. Uses of products produced from lignin pyrolysis are discussed to highlight the potential of using lignin as an energy resource to produce biooil, biochar and non-condensable gases (NCG).

    Results show that energy efficiencies differ significantly between various pyrolysis techniques, where microwave-assisted pyrolysis (MAP) shows the highest energy efficiency. Products produced from pyrolysis show a wide range of uses in many industrial applications. Lignin based products have the potential to replace many petroleum-based products which may contribute significantly to decrease pollutants in nature and gas emissions caused by combusting fossil fuels.

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  • 6.
    Abbas, Muhammad Tahir
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Improving the Energy Efficiency of Cellular IoT Device2023Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cellular Internet of Things (CIoT) has emerged as a promising technology to support applications that generate infrequent data. One requirement on these applications, often battery-powered devices, is low energy consumption to enable extended battery life. Narrowband IoT (NB-IoT) is a promising technology for IoT due to its low power consumption, which is essential for devices that need to run on battery power for extended periods. However, the current battery life of NB-IoT devices is only a few years, which is insufficient for many applications. This thesis investigates the impact of energy-saving mechanisms standardized by 3GPP on battery life of NB-IoT devices. The main research objective is to classify and analyze existing energy-saving solutions for CIoT and examine their limitations, to study the impact of standardized energy-saving mechanisms on the battery life of NB-IoT devices, both in isolation and combined, and to provide guidelines on how to configure NB-IoT devices to reduce energy consumption efficiently. The research aims to provide a deeper understanding of the effect of energy-saving mechanisms and best practices to balance energy efficiency and performance of NB-IoT devices. Applying the proposed solutions makes it possible to achieve a battery life of 10~years or more for CIoT devices.

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  • 7.
    Abbas, Muhammad Tahir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Eklund, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Rajiullah, Mohammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Caso, Giuseppe
    Ericsson Research.
    Kousias, Konstantinos
    Simula Research Laboratory, Norway.
    Alay, Özgü
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). University of Oslo, Norway.
    On the Energy-efficient Use of Discontinuous Reception and Release Assistance in NB-IoT2022Conference paper (Refereed)
    Abstract [en]

    Cellular Internet of Things (CIoT) is a Low-Power Wide-Area Network (LPWAN) technology. It aims for cheap, lowcomplexity IoT devices that enable large-scale deployments and wide-area coverage. Moreover, to make large-scale deployments of CIoT devices in remote and hard-to-access locations possible, a long device battery life is one of the main objectives of these devices. To this end, 3GPP has defined several energysaving mechanisms for CIoT technologies, not least for the Narrow-Band Internet of Things (NB-IoT) technology, one of the major CIoT technologies. Examples of mechanisms defined include CONNECTED-mode DRX (cDRX), Release Assistance Indicator (RAI), and Power Saving Mode (PSM). This paper considers the impact of the essential energy-saving mechanisms on minimizing the energy consumption of NB-IoT devices, especially the cDRX and RAI mechanisms. The paper uses a purpose-built NB-IoT simulator that has been tested in terms of its built-in energy-saving mechanisms and validated with realworld NB-IoT measurements. The simulated results show that it is possible to save 70%-90% in energy consumption by enabling the cDRX and RAI. In fact, the results suggest that a battery life of 10 years is only achievable provided the cDRX, RAI, and PSM energy-saving mechanisms are correctly configured and used

  • 8.
    Abbas, Muhammad Tahir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Eklund, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Impact of Tunable Parameters in NB-IoT Stack onthe Energy Consumption2019In: Proceedings of Fifteenth Swedish National Computer Networking Workshop (SNCNW), 2019Conference paper (Refereed)
    Abstract [en]

    This paper studies the impact of tunable parametersin the NB-IoT stack on the energy consumption of a user equipment(UE), e.g., a wireless sensor. NB-IoT is designed to enablemassive machine-type communications for UE while providing abattery lifetime of up to 10 years. To save battery power, most oftime the UE is in dormant state and unreachable. Still, duringthe CONNECTED and IDLE state, correct tuning of criticalparameters, like Discontinuous reception (DRX), and extendedDiscontinuous reception (eDRX), respectively, are essential to savebattery power. Moreover, the DRX and eDRX actions relate tovarious parameters which are needed to be tuned in order toachieve a required UE battery lifetime. The objective of thispaper is to observe the influence of an appropriate tuning ofthese parameters to reduce the risk of an early battery drainage

  • 9.
    Abbas, Muhammad Tahir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Eklund, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). Karlstad University, Faculty of Health, Science and Technology (starting 2013), Science, Mathematics and Engineering Education Research.
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Science, Mathematics and Engineering Education Research. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alay, Özgü
    University of Oslo and Simula Metropolitan, NOR.
    Katona, Sándor
    Ericsson AB.
    Seres, Gergely
    Ericsson AB.
    Rathonyi, Bela
    Ericsson AB.
    Guidelines for an Energy Efficient Tuning of the NB-IoT Stack2020In: 45th IEEE Conference on Local Computer Networks (LCN), IEEE Communications Society, 2020, p. 60-69, article id 9363265Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the energy consumptionof Narrowband IoT devices. The paper suggests that key tosaving energy for NB-IoT devices is the usage of full Discontinuous Reception (DRX), including the use of connected-mode DRX (cDRX): In some cases, cDRX reduced the energy consumption over a 10-year period with as much as 50%. However, the paper also suggests that tunable parameters, such as the inactivity timer, do have a significant impact. On the basis of our findings, guidelines are provided on how to tune the NB-IoT device so that it meets the target of the 3GPP, i.e., a 5-Wh battery should last for at least 10 years. It is further evident from our results that the energy consumption is largely dependent on the intensity and burstiness of the traffic, and thus could be significantly reduced if data is sent in bursts with less intensity,irrespective of cDRX support.

  • 10.
    Abbas, Muhammad Tahir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Eklund, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Rajiullah, Mohammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Caso, Giuseppe
    Ericsson Research, Sweden.
    Kousias, Konstantinos
    Simula Research Laboratory, Norway.
    Alay, Özgü
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). University of Oslo, Norway.
    Energy-Saving Solutions for Cellular Internet of Things - A Survey2022In: IEEE Access, E-ISSN 2169-3536, Vol. 10, p. 62096-62096Article in journal (Refereed)
    Abstract [en]

    The Cellular Internet of Things (CIoT), a new paradigm, paves the way for a large-scale deployment of IoT devices. CIoT promises enhanced coverage and massive deployment of low-cost IoT devices with an expected battery life of up to 10 years. However, such a long battery life can only be achieved provided the CIoT device is configured with energy efficiency in mind. This paper conducts a comprehensive survey on energy-saving solutions in 3GPP-based CIoT networks. In comparison to current studies, the contribution of this paper is the classification and an extensive analysis of existing energy-saving solutions for CIoT, e.g., the configuration of particular parameter values and software modifications of transport- or radio-layer protocols, while also stressing key parameters impacting the energy consumption such as the frequency of data reporting, discontinuous reception cycles (DRX), and Radio Resource Control (RRC) timers. In addition, we discuss shortcomings, limitations, and possible opportunities which can be investigated in the future to reduce the energy consumption of CIoT devices.

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  • 11.
    Abbas, Muhammad Tahir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Muhammad, Afaq
    Sarhad Univ Sci & Informat Technol, Pakistan.
    Song, Wang-Cheol
    Jeju Natl Univ, South Korea.
    SD-IoV: SDN enabled routing for internet of vehicles in road-aware approach2019In: Journal of Ambient Intelligence and Humanized Computing, ISSN 1868-5137, E-ISSN 1868-5145, Vol. 11, no 3, p. 1265-1280Article in journal (Refereed)
    Abstract [en]

    Proposing an optimal routing protocol for internet of vehicles with reduced overhead has endured to be a challenge owing to the incompetence of the current architecture to manage flexibility and scalability. The proposed architecture, therefore, consolidates an evolving network standard named as software defined networking in internet of vehicles. Which enables it to handle highly dynamic networks in an abstract way by dividing the data plane from the control plane. Firstly, road-aware routing strategy is introduced: a performance-enhanced routing protocol designed specifically for infrastructure-assisted vehicular networks. In which roads are divided into road segments, with road side units for multi-hop communication. A unique property of the proposed protocol is that it explores the cellular network to relay control messages to and from the controller with low latency. The concept of edge controller is introduced as an operational backbone of the vehicle grid in internet of vehicles, to have a real-time vehicle topology. Last but not least, a novel mathematical model is estimated which assists primary controller in a way to find not only a shortest but a durable path. The results illustrate the significant performance of the proposed protocol in terms of availability with limited routing overhead. In addition, we also found that edge controller contributes mainly to minimizes the path failure in the network.

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    fulltext
  • 12.
    Abbas, Shahrukh
    et al.
    National University of Sciences & Technology, PAK.
    Kazmi, Syed Ali
    National University of Sciences & Technology, PAK.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Javed, Adeel
    National University of Sciences & Technology, PAK.
    Naqvi, SR
    National University of Sciences & Technology, PAK.
    Ullah, Kafait
    National University of Sciences & Technology, PAK.
    Khan, Tauseef
    Natl Transmiss & Dispatch Co NTDC, PAK.
    Shin, Dong
    SungKyunKwan Univ SKKU, KOR.
    Impact Analysis of Large-Scale Wind Farms Integration in Weak Transmission Grid from Technical Perspectives2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 20, article id 5513Article in journal (Refereed)
    Abstract [en]

    The integration of commercial onshore large-scale wind farms into a national grid comes with several technical issues that predominately ensure power quality in accordance with respective grid codes. The resulting impacts are complemented with the absorption of larger amounts of reactive power by wind generators. In addition, seasonal variations and inter-farm wake effects further deteriorate the overall system performance and restrict the optimal use of available wind resources. This paper presented an assessment framework to address the power quality issues that have arisen after integrating large-scale wind farms into weak transmission grids, especially considering inter-farm wake effect, seasonal variations, reactive power depletion, and compensation with a variety of voltage-ampere reactive (Var) devices. Herein, we also proposed a recovery of significant active power deficits caused by the wake effect via increasing hub height of wind turbines. For large-scale wind energy penetration, a real case study was considered for three wind farms with a cumulative capacity of 154.4 MW integrated at a Nooriabad Grid in Pakistan to analyze their overall impacts. An actual test system was modeled in MATLAB Simulink for a composite analysis. Simulations were performed for various scenarios to consider wind intermittency, seasonal variations across four seasons, and wake effect. The capacitor banks and various flexible alternating current transmission systems (FACTS) devices were employed for a comparative analysis with and without considering the inter-farm wake effect. The power system parameters along with active and reactive power deficits were considered for comprehensive analysis. Unified power flow controller (UPFC) was found to be the best compensation device through comparative analysis, as it maintained voltage at nearly 1.002 pu, suppressed frequency transient in a range of 49.88-50.17 Hz, and avoided any resonance while maintaining power factors in an allowable range. Moreover, it also enhanced the power handling capability of the power system. The 20 m increase in hub height assisted the recovery of the active power deficit to 48%, which thus minimized the influence of the wake effect.

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  • 13.
    Abdelamir, Zulfaqar
    Karlstad University.
    Fabricability of a high alloy tool steel produced with LPBF, with a focus on part geometry2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM) is a promising manufacturing process that provides that ability to fabricate components with complex geometries with relatively low lead times compared to other manufacturing processes. This allows for more freedom of design, as prototypes can easily be produced throughout the development process. AM is also especially beneficial in tooling applications, where internal geometries such as cooling channels are required in order to improve the quality of the manufactured parts. These geometries are more difficult to produce with more conventional manufacturing methods such as forging or casting. Currently, Laser Powder Bed Fusion (LPBF) shows the most promise in the field of Additive Manufacturing (AM) of metals, as it offers the freedom to produce complex components with little post processing required. Additionally, post processing with Hot Isostatic Pressing (HIP) can be implemented to significantly enhance the final properties of the material. 

    The LPBF-process can produce many different defects within the parts such as: part porosity and lack of fusion. This is mainly due to the layer-by-layer configuration of the process. Parts can also experience large thermal fluctuations and rapid cooling rates which can generate large residual stresses. This can result in significant cracking in certain high alloyed materials which can impact part quality and  material properties. If the cracking is severe enough, it will result in failure of the entire component and render the entire parts completely useless. Post processing with HIP may remove some of these defects and reduce the residual stresses in the material and thus produce a material with properties that are satisfactory.

    The purpose of this thesis is to investigate the processability of a high alloy cold work tool steel with LPBF. The main focus is the influence of the processing parameters and part geometry on the quality of the produced parts. Furthermore, the influence of the processing parameters on defects and microstructure will also be investigated. The aim is to produce parts that can be enhanced with HIP as a post processing treatment. Additionally, the impact of HIP on the properties of the part will also be investigated in order to determine if the there are any improvements in terms ofreduction in part defects and the removal of any undesired microstructural features which are produced from the process.

    The experimental results showed that the processability of the tool steel is difficult. Several sample volumes were produced with varying processing parameters and scanning strategies, and all the specimens from all sample volumes exhibited some cracking. Parts produced with a combination of contouring and hatching strategy, where there is an internal structure showed the most promise, as these parts exhibited the least amount of severe cracking. However, additional research of the processing parameters and scanning strategies is required in order to reduce the amount of cracking of the external shell structure and thus, achieve proper densification of the parts when post processing with HIP.

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  • 14.
    Abdulhadi, Sami
    Karlstad University, Faculty of Technology and Science.
    ARM i inbyggt system: med prototyp2009Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Embedded systems has become more and more common in today's society. The embedded systems are included in almost everything today, from various vehicles to children's toys.

    Today's technology means that yesterday's solutions can be realised on a fraction of the area. More and more become surface mounted with smaller and more complex circuits. This is not always an advantage for the developers when assembling and soldering prototype circuit boards become a more difficult and/or an expensive process.

    The goal is to create an embedded system with an ARM-processor. The system will consist of USB-OTG, ethernet, various memory like FRAM and microSD and a display with touchscreen for user interface. The project includes everything from choice of components to test and verification with program code.

    The time was too short to include all the parts that was planned. The result of the project was a prototype card and two small program sequences, one that blinks the two light diodes on the card and one that writes a picture on the display.

    This embedded system is intended for evaluating ARM-processors by Mikrododakt AB.

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    ARM i inbyggt system - med prototyp
  • 15. Aboona, Yousi
    et al.
    Tummings, Alexander
    Effektivisering inom bygglogistik: En fallstudie över bygglogistiksproblem under produktionsprocess2021Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    In the construction sector there are currently high demands regarding short project times. As a result of this, the constructer demands lower costs, which in itself leads to challenges to meet the requirements. Other contributing factors to difficult-to-achieve requirements are changed project conditions and varying material flows. As a result, the majority of all recent reports have been identified as logistics-related problems.

    In order to streamline the production process and meet the planned requirements, it is required to logistically plan the project at an early stage by having good planning, good communication and cooperation at the construction site. A large part of logistics is covered by planning and utilizing transport and material deliveries in an efficient way.

    The purpose of this degree project is to investigate how construction logistics work at Veiddekkke's workplaces, where one of their ongoing projects includes OKQ8 in Karlstad. This is to be able to identify the logistics problems that may arise during the project and for what reasons.

    After identifying the logistical problems that may arise at the construction site, the goal is to develop proposals and implement these proposal solutions in order to avoid these problems recurring in future construction projects.

    At the beginning of this thesis, an extensive literature study was conducted based on various books, reports and research articles to obtain as much knowledge as possible in the field. To gather the necessary information about the OKQ8 project, a case study was conducted at the construction site. The methods used for data collection were surveys, interviews, observations, and work diaries. Site manager and supervisor were interviewed, and different types of observations were made at the workplace.

    The results show that the construction logistics at Veidekke work well in general, but sometimes problems arise during the production process which can affect the project. The two major types of problems identified are transport and material deliveries. However, there are also other types of factors that can affect construction logistics, such as poor communication and poor planning.

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    Effektivisering inom bygglogistik
  • 16.
    Abrahamsson, Adam
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    de Bourgh, Simon
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Hållbarhetscertifieringssystem i anläggningsbranschen: En studie om upphandlingskrav kopplat till hållbarhetscertifieringar i offentliga upphandlingar2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Sustainability rating schemes has come to be used extensively since it´s arrival to Sweden during the 21th century. Today, the number of sustainability certifications increases for projects in the construction industry while only a few projects has been certified in the civil engineering industry. The reasons of the interesting development has been studied by investigating how the construction industry clients in the public sector should be able to claim use of sustainability rating schemes without infracting the Swedish public procurement act.

    The study has been conducted by literature- and interview research. Interviews were conducted with various stakeholders in the industry. The purpose was to obtain an unambiguous opinion of how clients should require use of sustainability rating schemes in public procurements. The study also discussed how stakeholders monitor and evaluate their work. The literature research analyzes previous work in the topic and evaluates procurements which contains requirements of sustainability rating schemes.

    The overall conclusions from this study is:

    • The industry demands a standardized framework about how to phrase requirements. Public clients should procure likewise, regardless of their location in Sweden.

    • More pilot projects must be implemented to find out how to achieve maximum benefit with sustainability rating schemes.

    • The industry wants more clear and measurable requirements.

    • Not to be contrary to the Swedish public procurement act, clients can phrase functional requirements based on the manual of the sustainability rating scheme they wish to use.

    • The clients should not worry about appeals, since appealed procurements because of sustainability requirements is rare. It is important to have clearly phrased requirements where the choice of sustainability rating scheme, specified criteria and level is clarified.

    • By the new EU-directives comes an update of the Swedish procurement act, which will enforce in 2016 with the intention of making it easier to set requirements for sustainability rating schemes.

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    Hållbarhetscertifieringssystem i anläggningsbranschen
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    Arkivfi
  • 17.
    Abrahamsson, Erika
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Gröna tak - potentialen för dagvattenreglering i Karlstad: Simuleringar i Mike Urban2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As urban areas become more populated and denser, stormwater management becomes an important matter. Since natural areas are becoming exploited and green areas in cities are removed the stormwater flow increases due to the conversion of impermeable surfaces into hard surface areas. The increase in stormwater flow can cause flooding if the pipeline system is insufficient.

    Change in climate caused by anthropogenic emissions will expose our communities to difficult challenges. Urban flooding from sewers is one of them, and may become more frequent in parts of the world where precipitation is predicted to increase in the future. In order to develop our cities in a sustainable manner and create resilience, the urban drainage system has to be a part of this development. Many of the techniques related to sustainable urban drainage systems, like storage reservoirs and open channels, require access to land space. However, about 40-50 % of the impermeable surfaces in cities consist of roof. Consequently, an interesting alternative to decrease stormwater flow is green roof due to its ability to reduce and attenuate the flow.

    The aim of this thesis is to demonstrate the benefits of green roof’s stormwater management through simulations in Mike Urban. The simulations are made over two neighborhoods in Karlstad with future climate changes. The simulations indicated that green roof in these neighborhoods show good potential to lower the risk of flooding and the numbers of flooded wells by a 10- and 2-year rain is decreased by 42 and 58 %.

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  • 18.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energianvändning vid pelletering: En undersökning av strömningsenergins betydelse för den totala energianvändningen vid pelletering2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Biofuels make up 25% of Sweden’s energy supply and the majority of biofuels used are made from wood. Wood pellets is one type of biofuel and in Sweden, 1.6 million tonnes of wood pellets were produced in 2018. Different pellet properties such as durability and energy use for production is often tested in a single pellet press. The total energy use for making a pellet in an industrial scale machine is the sum of the energy required for three different component sequences, compression, friction and flow. Flow is when the material that lies on the surfaces between the press channel openings is compressed and pushed downwards towards the coned openings and the materiel in the coned opening is deformed and pushed down to the press channel.

    Only compression and friction can be studied using a conventional single pellet press. Thus, this study focuses on the impact of the flow component on the total energy use for pelletizing. In order to do this, energy used for compression, friction and flow, as well as the power required for the material to enter the flow component, Fflow, has been studied for three different particle sizes.

    Fresh spruce with a moisture content of 10% has been pressed in different dies. With these pressings, the impact of the flow component, as well as the impact of pressing material located around the coned press channel opening on the total energy use was determined.

    Particle size did not affect energy use. Fflow was higher for pressings with material located on the surface around the coned opening, compared to pressings without. This resulted in an increased compression energy for pressings with material around the coned opening. The material located around the press channel opening affected the pelletizing so that the produced pellet was 1 mm shorter, which resulted in a lower energy use for the friction component. Energy used by the flow component made up over 43-57% of the total energy use. The part of the flow energy that is needed to compress the material around the press channel opening and move that material towards the opening stood for 35-52% of the total energy use for palletization.

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  • 19.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energieffektivisering av fabrik inom tillverkande industri: Utvärdering av åtgärdsförslag2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    June 1st, 2014, the law on energy audits of large enterprises was introduces as a way of promoting energy efficiency and to help fulfil the demands from the EU energy efficiency directive. One company that this law applies to is Talent Plastics in Gothenburg. In 2017 an energy audit was conducted at the company by WSP in Karlstad. This audit has been used as a basis for this study. The purpose of this study has been to present solutions for reducing the energy use as Talent Plastics in Gothenburg.

    In this study, an energy balance for the facility has been modelled. This model has then been used in order to evaluate some of the different solutions presented in the previous energy audit as well as some new solutions that have been identified.

    The solutions that have been studied are:

    Heat recovery from the process cooling by installing a heating battery in

    ventilation systemsHeat recovery from the process cooling by pre-heating ventilation airUpdating old extruder machinesHeat recovery from the compressed air systemUsing outside air for the compressed air systemUpdate of the existing heat recovery system installed in the production

    ventilation system

    Based on the results presented in this report the system today is inefficient with a large need for heat whilst a lot of energy is cooled through process cooling. The energy balance presented showed a higher use of energy for heating of ventilation air compared to the results presented in the previous energy audit. This is a consequence of the assumptions made when conducting an energy audit. By underestimating the energy need for the heating of ventilation air, the potential energy savings from solutions including heat recovery in the ventilation systems has been underestimated.

    Out of the solutions investigated in this study, updating the heat recovery system in the ventilation system for production spaces resulted in the largest energy savings with savings of 192 MWh per year. The maximum energy savings using heat recovery from the process cooling were 202 MWh/year. This solution had a pay-off time of 0,7 years. The results showed that heat recovery from the compressed air system is not a suitable solution for the facility.

    When combining different solutions updating the existing heat recovery system installed in the production ventilation system combined with pre-heating and installation of a heating battery in the same ventilation system would result in energy savings of 323 MWh per year. This represents 14 % of the total energy use for the facility and savings of 226 thousand Swedish krona per year.

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    Energieffektivisering av fabrik inom tillverkande industri
  • 20.
    Abshirini, Ehsan
    KTH, .
    Interaction between rivers and morphology of cities in Sweden2014In: Our common future in urban morphology: Urban Transformations in the Medieval Town of Monção / [ed] Virgillio Torres, Joaoa Delgado, Porto: FEUP edições (Faculdade de Engenharia da Universidade do Porto Edicoes) , 2014Conference paper (Refereed)
    Abstract [en]

    Rivers as one of the most important topographic factor have played a strategic role not only on the appearance of cities but they also affect the structure and morphology of cities. In this paper I intend to find out the influence of rivers on the morphology of a cities and discuss that how a city in its physical network interacts with a river flowing inside. My study area is river-cities in Sweden in which they have not received much attention in this issue. To this purpose I use space syntax method integrating with geospatial analysis and extract the properties of physical form of cities in terms of global and local integration value, choice value and so on. Comparing the states of presence and absence of rivers in these cities as well as evaluating the effect of rivers on the morphology of areas located in different banks of rivers are also part of interest in this paper. The primary result shows that although a river is not comparable to a city based on size and the area occupied by, it has a significant effect on the form of a city in both global and local properties. In addition, tracking the pattern of river-cities and their interaction to rivers may lead us to interoperate the physical form of these cities in terms of structured and distributed cities.

  • 21.
    Abshirini, Ehsan
    et al.
    KTH, Samhällsplanering och miljö.
    Koch, Daniel
    KTH, Arkitektonisk gestaltning.
    Resilience, space syntax and spatialinterfaces: The case of river cities2017In: A|Z ITU Journal of the Faculty of Architecture, ISSN 1303-7005, Vol. 14, no 1, p. 25-41Article in journal (Refereed)
    Abstract [en]

    Resilience defined as the capacity of a system to manage impacts, keep its efficiency and continue its development has been scrutinized by researchers from different points of view over the past decades. Due to the prominence of resilience in urban planning, this paper intends to find out how the spatial structure of cities deals with disturbances, and if geographical phenomena such as rivers affect the resilience in cities. Using the space syntax methods syntactically analyze the resilience in cities, we innovatively introduce two measures; similarity and sameness. These measures are in relation with the syntactical properties of cities and compare the degree of resilience between different groups. Similarity measures the degree to which each city retains the relative magnitude of its foreground network after a disturbance and sameness is the degree to which each city retains the same segments as its foreground network after a disturbance. Likewise to network resilience studies, we apply different disturbances on cities and explore the reaction of cities to disturbances in terms of size of the foreground network and which segments are parts thereof. We then compare different groups based on these measurements as a method to analyze sameness and similarity. The results show that the resilience, in the way we define it, is different in different cities depending on in which view and based on which parameters we are discussing the resilience. Additionally morphological phenomena such as rivers have a great impact on the structure of cities and in turn on their resilience.

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  • 22.
    Abshirini, Ehsan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). KTH, Geoinformatik.
    Koch, Daniel
    KTH, Arkitektur.
    Rivers as integration devices in cities2016In: City, Territory and Architecture, E-ISSN 2195-2701, Vol. 3, no 1, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Background: As dynamic systems rivers and cities have been in interaction under changing relations over time, and the morphology of many cities has risen through a long and steady struggle between the city functions and the river system flowing inside. This makes river cities an interesting case to study how the presence of geographical features interacts with spatial morphology in the formation of cities.

    Methods: The basis of this research is enabled by utilizing a novel model for cross-city comparison presented by Hillier in his Santiago keynote in 2012 called a “star model”. This is done on large samples of cities investigating concurrent configurations, as well as how the properties in this star model react to specific forms of disturbance.

    Results: Results illustrate that the foreground network as identified through maximum choice values in cities are more vital to the structure of cities than the bridges. The overall syntactic structure tends to retain its character (degree of distributedness) and the location of its foreground network (which street segments constitute the foreground network) even when bridges are targeted. Furthermore, counter to the initial hypothesis, river cities tend to change less than non-river cities after targeted disturbance of the systems. Finally, the results show that while there is a statistical morphological difference between river cities and non-river cities, this difference is not directly explained through the bridges.

    Conclusion: Integrating space syntax with statistical and geospatial analysis can throw light on the way in which the properties of city networks and urban structure reflect the relative effect of rivers on the morphology of river cities. The paper, finally, contributes through offering one piece of a better perception of the structure of river-cities that can support strategies of river-cities interaction as well as enhance our knowledge on the constraints and limits to that interaction.

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  • 23.
    Ackerstierna, Paula
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    The Environmental Impact of an Automotive Plastic Component: A lifecycle approach of a deco panel scenario analysis of two different plastics2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The transport sector is a major end-user of energy. As consumers are becoming aware and conscious of their environmental footprint making the enviromental footprint of automobile components one of the requirements in new product design development.

    The purpose of the study is to identify environmental impacts of a plastic panel. The main objective of the study is to perform an environmental life cycle assessment (E-LCA) of an existing panel regarding four scenarios with a nonbio-based plastic and a bio-based plastic. The first two scenarios have the same production and use phase, but different end-of-life treatments. The plastic in these scenarios is non-biobased. The last two scenarios have the same bio-based plastic and use phase, but different end-of-life-treatments. The first three scenarios have a surface material covering the plastic. The environmental impacts analyzed are global warming potential, acidification potential, eutrophication potential, photochemical ozone creation potential, primary energy demand and particulate matter.

    The analysis is carried out according to the ISO14040/44 with the four steps of LCA: 1) Goal and Scope Definition, 2) Inventory Analysis, 3) Impact Assessment, and 4) Interpretation. The functional unit of the anaysis is a plastic panel. The inventory was collected by literature, the LCA software GaBi, and the commissoner of the study. The environmental impact assessment was conducted in GaBi 8 with the method of CML2015, Primary Energy, and IMPACT2002+. A dominance and a contribution analyses were applied to identify the hotspots of the life cycle. The hotspot of the life cycle was identified to be the production phase.

    The main contributor within the scenarios was the plastic production, specifically the granulates and the fiber fillings. The bio-based plastic reduced the impacts compared to the non-bio-based in five out of six cases. However, the photochemical ozone creation potential for both plastics were the same. The bio-based plastic reduced the GWP 16%, AP by 1%, EP by less than 1%, and PED by 19%. If the surface cover in aluminum was removed, the GWP was reduced by 46%, AP by 35%, EP by29%, POCP by 36%, PED by 42%and PM by 40%.  The transportation contributed most to impacts in the acidification potential, eutrophication potential, and particulate matter. The transportation’s impacts were greater in the bio-based plastic than the non-bio-based.

    The granulates of the plastic along with the injection molding are the main contributors due to usage of coal-based electricity for the injection molding and oil for the plastic production. The values used in the study are based on country averages which may differ depending on geographic location and its development as China is a country with a large area. The GWP is the highest value of the impacts analyzed, but even though the other are small fractions these may cause great damages. These damages can irritate eyes, damage lungs and destroy photosynthesis.

    By using recycled material for products instead of new materials, as done in the study, the impacts could be lower. As some previous studies agrees, the usage of bio-plastics lowers the environmental impact by a few percentages.  The bioplastic is an environmentally sustainable option to the current plastic as the location of the panel is not sensitive to excessive heat.

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  • 24.
    Aderne, Rian E.
    et al.
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Borges, Bruno Gabriel A. L.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Avila, Harold C.
    University of Atlantic, COL.
    von Kieseritzky, Fredrik
    Karolinska Institutet.
    Hellberg, Jonas
    Chemtron AB, Sweden.
    Koehler, Marlus
    Universidade Federal do Paraná-UFPR, BRA.
    Cremona, Marco
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Roman, Lucimara S.
    Universidade Federal do Paraná-UFPR, BRA.
    Araujo, Moyses C.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Rocco, Maria Luiza M.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    On the energy gap determination of organic optoelectronic materials: the case of porphyrin derivatives2022In: Materials Advances, E-ISSN 2633-5409, no 3, p. 1791-1803Article in journal (Refereed)
    Abstract [en]

    The correct determination of the ionization potential (IP) and electron affinity (EA) as well as the energy gap is essential to properly characterize a series of key phenomena related to the applications of organic semiconductors. For example, energy offsets play an essential role in charge separation in organic photovoltaics. Yet there has been a lot of confusion involving the real physical meaning behind those quantities. Experimentally the energy gap can be measured by direct techniques such as UV-Vis absorption, or indirect techniques such as cyclic voltammetry (CV). Another spectroscopic method is the Reflection Electron Energy Loss Spectroscopy (REELS). Regarding data correlation, there is little consensus on how the REELS' energy gap can be interpreted in light of the energies obtained from other methodologies such as CV, UV-Vis, or photoemission. In addition, even data acquired using those traditional techniques has been misinterpreted or applied to derive conclusions beyond the limits imposed by the physics of the measurement. A similar situation also happens when different theoretical approaches are used to assess the energy gap or employed to explain outcomes from experiments. By using a set of porphyrin derivatives as model molecules, we discuss some key aspects of those important issues. The peculiar properties of these porphyrins demonstrate that even straightforward measurements or calculations performed in a group of very similar molecules need a careful interpretation of the outcomes. Differences up to 660 meV (similar to 190 meV) are found comparing REELS (electrochemical) measurements with UV-Vis energy gaps, for instance. From the theoretical point of view, a reasonable agreement with electrochemical measurements of the IP, EA, and the gap of the porphyrins is only obtained when the calculations involve the full thermodynamics of the redox processes. The purpose of this work is to shed light on the differences and similarities of those aforementioned characterization methods and provide some insight that might help one to develop a critical analysis of the different experimental and theoretical methodologies.

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  • 25.
    Adeva Rodil, Teresa
    Karlstad University, Division for Engineering Sciences, Physics and Mathematics.
    Edge effect on abrasive wear mechanisms and wear resistance in WC-6wt.% Co hardmetals2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

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

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

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

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

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  • 26.
    Adler, Anneli
    et al.
    Swedish University of Agricultural Sciences.
    Kumaniaev, Ivan
    Stockholm University.
    Karacic, Almir
    Swedish University of Agricultural Sciences.
    Baddigam, Kiran Reddy
    Stockholm University.
    Hanes, Rebecca J.
    Strategic Energy Analysis Center, USA; Center for Bioenergy Innovation, USA.
    Subbotina, Elena
    Stockholm University.
    Bartling, Andrew W.
    Center for Bioenergy Innovation, USA; Catalytic Carbon Transformation and Scale-up Center, USA.
    Huertas-Alonso, Alberto J.
    Stockholm University; University of Castilla-La Mancha, Spain.
    Moreno, Andres
    University of Castilla-La Mancha, Spain.
    Håkansson, Helena
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Mathew, Aji P.
    Stockholm University.
    Beckham, Gregg T.
    Center for Bioenergy Innovation, USA; Renewable Resources and Enabling Sciences Center; USA.
    Samec, Joseph S.M.
    Stockholm University; Chulalongkorn University, Thailand .
    Lignin-first biorefining of Nordic poplar to produce cellulose fibers could displace cotton production on agricultural lands2022In: Joule, E-ISSN 2542-4351, Vol. 6, no 8, p. 1845-1858Article in journal (Refereed)
    Abstract [en]

    Here, we show that lignin-first biorefining of poplar can enable the production of dissolving cellulose pulp that can produce regenerated cellulose, which could substitute cotton. These results in turn indicate that agricultural land dedicated to cotton could be reclaimed for food production by extending poplar plantations to produce textile fibers. Based on climate-adapted poplar clones capable of growth on marginal lands in the Nordic region, we estimate an environmentally sustainable annual biomass production of ∼11 tonnes/ha. At scale, lignin-first biorefining of this poplar could annually generate 2.4 tonnes/ha of dissolving pulp for textiles and 1.1 m3 biofuels. Life cycle assessment indicates that, relative to cotton production, this approach could substantially reduce water consumption and identifies certain areas for further improvement. Overall, this work highlights a new value chain to reduce the environmental footprint of textiles, chemicals, and biofuels while enabling land reclamation and water savings from cotton back to food production.

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  • 27.
    Adolfsson, Antonia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Off grid boende: Dimensionering samt värdering av möjliga system för hantering av avlopp och energiförsörjning2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Bostadsbristen är ett ständigt faktum i Sverige idag och i takt med att boendepriserna ökar så ökar också intresset för att bygga sin egen bostad. Arkitektfirman Tengbom i Karlstad har startat upp ett projekt, Portable Empowerment, som bygger på visionen om att skapa en portabel bostad som ska kunna fungera som en lösning när ett plötsligt behov av bostäder uppstår. För att bostäderna ska kunna flyttas runt krävs det att lösningar för energi- och avloppssystem finns integrerade i bostaden och ska kunna flyttas med för att göra bostaden portabel. För att detta ska vara möjligt krävs det avlopps- och energisystem som är off grid.

    Off grid betyder att systemet inte är kopplat till kommunalt avlopp eller elnät. Det finns sedan länge sätt att lösa både avlopp och energiförsörjning off grid och några exempel där det tillämpas är husvagnen och den klassiska sommarstugan, men de är allt som oftast inte anpassade för bruk året runt. Målet med denna studie är att identifiera samt värdera avlopps- och energisystem som kan tillgodose behoven i en liten bostad som brukas året runt av två personer. Bostaden har sin utgångspunkt i de ritningar som tagits fram av Tengbom för deras projekt Portable Empowerment.

    För att identifiera system som kan tillgodose behoven i bostaden har modeller byggts upp och simuleringar skett där system lämpade för off grid inkluderats. Lösningarna har sedan jämförts med varandra med hjälp av värderingsmatriser där portabilitet, kostnad, miljö och användarvänlighet för varje system värderats.

    Resultatet av studien visar att det finns flera system för både energi och avlopp som kan tillgodose behoven i bostaden året om. Flera av systemen uppfyller kraven för en portabel bostad och det är med andra ord möjligt att uppfylla Tengboms vision om ett fullständigt portabelt boende. Jämfört med en ”vanlig” bostad som är ansluten till vatten- och elnät är dock off grid-lösningarna betydligt mer tidskrävande. Genom att installera ett eget system med lösningar för enbart den egna bostaden tar brukaren också på sig det fulla ansvaret, något som kan tänkas vara en belastning för vissa brukare och en frihet för andra.

    Ur ekonomisk synpunkt visar studien att på energisidan är det svårt att hitta ett off grid-system som är billigare än on grid-systemet där en luftvärmepump installerats. Däremot är anslutningen till ett kommunalt avlopp betydligt dyrare, mellan 100 000-150 000 kronor mer, än att anlägga till exempel en egen infiltrationsanläggning i anslutning till den egna bostaden.

    För att utveckla denna studie bör möjligheten att bygga off grid-byar undersökas. Genom att bygga upp ett samhälle om ett stort bostadsbehov skulle uppstå kan energi- och avloppsanläggningar delas. Anläggningarna har större kapacitet och genom att dela på dessa kan både ansvar och kostnad minskas.

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  • 28.
    Adolfsson, Karin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Albinsson, Stina
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Friår - av vilken anledning?: Kopplingar mellan anledningar till friår och livsformerna2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Undersökningens syfte är att se vilka anledningar individen har till att välja friår och hur det kopplas samman med livsformerna de lever. Syftet har också varit att se individens upplevelse av friåret och vad de använt friåret till. Undersökningen bygger på kvalitativa intervjuer med sex friårslediga. Intervjuerna har handlat om individens upplevelse av friåret och tiden före det.

    Friår är en arbetsmarknadspolitisk åtgärd med målsättning att ge arbetstagare en längre ledighet från sitt arbete. Arbetslösa får samtidigt en chans att komma in på arbetsmarknaden. Friåret innebär att vara ledig från sitt arbete i tre till tolv månader för att kunna göra något annat utanför arbetsplatsen. För att kunna undersöka av vilka anledningar individen har friår och hur det kopplas med de olika sociala strukturer som villkorar människors vardag. Vi har studerat om livsformsanalysen kan användas till att beskriva, förklara och förstå skillnaderna i människors vardag. Livsformerna är sociala strukturer som villkorar människors vardag. De olika livsformsbegreppen som vi har använt oss av är arbetarlivsformen – husmorslivsformen, karriärenslivsform – representationshustrunslivsform och självständighetens livsform – medhjälperskans livsform. Det är dock vanligt att leva en blandning mellan två eller flera livsformer, det kallas en blandform.

    Vi har kommit fram till att livsformerna till viss del kan kopplas samman med hur intervjupersonerna lever under sitt friår och av vilken anledning de har friår. Det visar sig i att de som använder friåret till att starta ett företag lever till stor del självständighetens livsform. Att använda friåret till utbildning kan kopplas samman med karriärens livsformer. Vidare kan vi se att karriärenslivsform kan kopplas samman med att pressen på arbetet är stor och då är rekreation under friåret vanligt. Många kvinnor lever blandformer och det gör att de har svårt att kombinera de olika arbets- och kärleksformerna. De använder friåret till att ta hand om sin familj och sig själva.

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  • 29.
    Adolfsson, Rasmus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Utformning av en infästningsstandard: En utveckling av kvalitetsarbetet hos Nordmarkens Fasader AB2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    As the construction industry today is increasing the demands on its actors and procedures to ensurethe quality of the final product, the work on quality assurance has increased in a greater degree.Quality assurance involves a systematic approach that often follow a specific quality system orquality mark. That this is conducted is often demonstrated by a certain certification.Nordmarkens Fasader in Töcksfors is a manufacturer and installator of windows, doors, walls androofs in aluminum and glass. To ensure the quality of their products, they work for the P-markingsystem that later allows them to P-label their products. The P-mark is the Science Partners ownquality mark and proves, among other things, that the product complies with statutory or regulatoryrequirements but also in most cases higher standards demanded by the market.In their work, Nordmarkens Fasader follows a quality manual, which in its turn is modeled after therules for P-marking. This is the official summarized description of the P-marking and contains orrefers to all the documents and document types included in the quality system of NordmarkensFasader.For the products of Nordmarkens Fasader to be developed a further step in working towards a goodquality and function, they want to establish drawings that deal with attaching elements in the wall, inthe quality manual. All this to get better track of what happens to the product after manufacture.Something that makes this even more important is that they do not always handle assembly of theirproducts. A standard of attachments in this case would result in that they can influence whathappens after manufacture. To achieve this it was necessary for a standard of attachments ofelements to be designed and then also integrated in the quality manual.Because there are many wall types to choose from, the most common and most abundant of thesewas elected. It all resulted in a number of standard drawings showing where some of the products ofNordmarkens Fasader should be attached in the selected wall. For this to be put into use in everydaylife it also had to be integrated into the quality manual. In addition to these standard drawings, themanual were changed while new documents also were created in this. All to achieve the best resultswith the quality work at Nordmarkens Fasader.This work will serve as a basis for future work on attachment drawings, in the quality manual, asthere is interest in bringing in multi-wall types in this.

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  • 30.
    Adolfsson, Robin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Jönsson, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Är SundaHus materialklassning kompatibel med Miljöbyggnads, BREEAMs och LEEDs materialkrav?: En studie om SundaHus miljöklassningar.2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    We live in a society where there is a shortage of housing and the demand for new and sustainable buildings is growing. The houses that are being built today are focused on being energy efficient to save resources. Something that is forgotten is the choice of materials to house constructions. Materials can affect nature and people from the cradle to the grave by for example material hazardous components. The certification systems Miljöbyggnad, BREEAM and LEED have been checked and their material criteria have been defined. Through a selection of construction materials taken from SundaHus a review has been made of these materials towards the certification systems´ criteria on materials to see if they are compatible. The minority of the criteria were reviewed to separate materials and could be verified in SundaHus. Almost all materials passed the criteria that could be used of Miljöbyggnad and BREEAM regardless of classification in SundaHus. None of the LEED criteria were compatible with SundaHus for separate materials. The fact that the worse classifications in SundaHus could pass the criteria that were reviewed indicates that the requirements in environmental certification systems are too low. Higher and more demands should be made on individual materials and the hazardous substances in them.

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  • 31.
    Aeyadi, Amin
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Formation of protective lubricious oxide layers on the surface of nitrogen alloyed steels in self-mated sliding2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 32.
    Afifi, Haitham
    et al.
    Hasso Platter Institute, Germany.
    Ramaswamy, Arunselvan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Karl, Holger
    Hasso Platter Institute, Germany.
    Reinforcement learning for autonomous vehicle movements in wireless multimedia applications2023In: Pervasive and Mobile Computing, ISSN 1574-1192, E-ISSN 1873-1589, Vol. 92, article id 101799Article in journal (Refereed)
    Abstract [en]

    We develop a Deep Reinforcement Learning (DeepRL)-based, multi-agent algorithm to efficiently control autonomous vehicles that are typically used within the context of Wireless Sensor Networks (WSNs), in order to boost application performance. As an application example, we consider wireless acoustic sensor networks where a group of speakers move inside a room. In a traditional setup, microphones cannot move autonomously and are, e.g., located at fixed positions. We claim that autonomously moving microphones improve the application performance. To control these movements, we compare simple greedy heuristics against a DeepRL solution and show that the latter achieves best application performance. As the range of audio applications is broad and each has its own (subjective) per-formance metric, we replace those application metrics by two immediately observable ones: First, quality of information (QoI), which is used to measure the quality of sensed data (e.g., audio signal strength). Second, quality of service (QoS), which is used to measure the network's performance when forwarding data (e.g., delay). In this context, we propose two multi-agent solutions (where one agent controls one microphone) and show that they perform similarly to a single-agent solution (where one agent controls all microphones and has a global knowledge). Moreover, we show via simulations and theoretical analysis how other parameters such as the number of microphones and their speed impacts performance.

  • 33.
    Afverberg, Marcus
    Karlstad University.
    Optimering vid byte av fyllningsplatta2018Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport är en del av ett examensarbete på högskoleprogrammet i maskinteknik vid

    Karlstads Universitet med programkod MSGC17. Arbetet omfattar 22.5 högskolepoäng.

    Arbetet har utförts på Swegon Operations AB i Arvika.

    På fabriken i Arvika tillverkas ljuddämpare för ventilationssystem. I tillverkningscellen där

    dessa ljuddämpare tillverkas sker ett moment där en platta ska bytas mot en annan platta av en

    robot, detta moment fungerar inte optimalt och orsakar stora störningar i produktionen. Dessa

    plattor kallas fyllningsplattor. Varje modell av ljuddämparna har en egen fyllningsplatta. Vid

    tillverkning måste dessa plattor alltså bytas vid byte av storlek av ljuddämpare. Målet med

    projektet är att hitta en lösning på problemet.

    För att nå målet med projektet utfördes arbetet enligt produktutvecklingsprocessen. Utifrån

    förundersökningen som bestod av att samla in data om hur situationen såg ut idag och vad

    som felade skapades en kravspecifikation för den nya lösningen. Koncept skapades i

    idégenereringsprocessen som sedan sållades för att ta fram den bästa lösningen. En

    layoutkonstruktion skapades av konceptet.

    Projektet resulterade i en lösning där alla fyllningsplattor ersattes med en fixerad platta som

    passar alla storlekar av ljuddämparna. Detta genom en fyllningsplatta med slitsade hål som

    fyllningsrören kan förflytta sig i med hjälp av motordrift. Detta medför att roboten helt enkelt

    kan tas bort.

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  • 34.
    Afzal, Zeeshan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Life of a Security Middlebox: Challenges with Emerging Protocols and Technologies2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of today has intermediary devices known as middleboxes that perform more functions than the normal packet forwarding function of a router. Security middleboxes are a subset of these middleboxes and face an increasingly difficult task to perform their functions correctly. These middleboxes make many assumptions about the traffic that may not hold true any longer with the advent of new protocols such as MPTCP and technologies like end-to-end encryption.

    The work in this thesis focuses on security middleboxes and the challenges they face. We develop methods and solutions to help these security middleboxes continue to function correctly. In particular, we investigate the case of using MPTCP over traditional security infrastructure as well as the case of end-to-end encryption. We study how practical it is to evade a security middlebox by fragmenting and sending traffic across multiple paths using MPTCP. We then go on to propose possible solutions to detect such attacks and implement them. The potential MPTCP scenario where security middleboxes only have access to part of the traffic is also investigated and addressed. Moreover, the thesis contributes a machine learning based approach to help security middleboxes detect malware in encrypted traffic without decryption.

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  • 35.
    Agardson, Agnes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Konceptframtagning av maskinstativ för användning i nyttofordon: Design för möjliggörande av ergonomisk och enkel maskinanvändning2023Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This Bachelor of Science thesis has been carried out during the spring of 2023 as a part of thecourse Degree Project for Bachelor of Science in Innovation and Design Engineering atKarlstad University. The degree project comprises 22,5 credits and the responsible student isAgnes Agardson with Johan Strandberg as supervisor and Leo De Vin as examiner.

    The project is performed in collaboration with the consulting company Rejlers on behalf ofone of their clients. In earlier stages of this cooperation, a machine has been developed andthis project is about further development within that same area. The purpose of this thesiswork is to create a solution on how to implement this machine in a commercial vehicle andadapt it to the user's needs and wishes and then perform a product development process withthe goal of developing a proposal solution that is presented with sketches, a prototype and CAD models.

    The main parts of the process has been divided into phases, a start-up, exploring, define,develop, deliver and a final phase that include a summary of the deliver phase, a writtenthesis, a final presentation and an exhibition. Some elements that were important in thisproject under these headings were, among other things, project plan, feasibility study, problemformulation, requirement specification, idea generation, concept selection, conceptdevelopment and construction.

    The process resulted in a concept proposal of a machine stand that is presented primarily via aCAD model but also with the help of sketches and a simple prototype. This concept proposalsolves the project’s main problem formulation and meets all predetermined requirements. Thesolution involves a foundation made of bent stainless steel sheet that is attached to the floor ofthe cargo compartment of a van. In this foundation, rails can be attached at different heights toadapt to the user’s height and position of the product, in turn a plate is attached to the rails, towhich the machine is attached. A locking function prevents the machine from moving wheninside the car and also allows the solution to be pulled out in several positions, a user modewhere the machine is only pulled out enough to enable use and a so-called service modewhere the machine is pulled out to the maximum to enable maintenance.  

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    Konceptframtagning av maskinstativ för användning i nyttofordon
  • 36.
    Agestam, Malin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Bio-based barriers against water and moisture: A study of different typrd of bio-based barriers for future food packaging2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is a need to develop more sustainable packaging products in the food packaging industry. An alternative to the common petroleum-based and synthetic barriers in paperboard are biopolymers such as starch, polylactic acid and wax with different modifications. The aim of this study was to study different types of biobased barriers against water and vapor on paperboard for future food packaging. All barriers were rod coated and their water and vapor barrier properties were tested by pinholes, coating weight, Cobb600, drop shape analysis (DSA), water vapor transmission rate (WVTR) and scanning electron microscopy (SEM). In addition, PLA were heat treated. The heat treatment method was calibrated using air permeance as a guidance of the barriers performance before further testing. Starch had an even coating but were very hydrophilic, resulting in a bad water and vapor barrier. PLA had a high contact angle during drop shape analysis, supposedly caused by the chemically hydrophobic surface of the untreated PLA structure combined with the surface topography shown in SEM. Despite the high contact angle, PLA had high Cobb600 and WVTR values. Heat treatment of PLA changed the structure of the barrier as shown during SEM and the barriers performance against water and vapor was improved. Wax had an uneven coating and therefore air drying in room temperature was tested. The result was a more even coating with lower Cobb600 and WVTR values. Future studies need to be done regarding the heat treatment of PLA. The dispersion technique needs scaling up and further testing before application on an industrial level.

  • 37.
    Agnelli, Filippo
    et al.
    Ecole Polytech, FRA.
    Constantinescu, Andrei
    Ecole Polytech, FRA.
    Nika, Grigor
    Weierstrass Inst Appl Anal & Stochast, DEU.
    Design and testing of 3D-printed micro-architectured polymer materials exhibiting a negative Poisson’s ratio2020In: Continuum Mechanics and Thermodynamics, ISSN 0935-1175, E-ISSN 1432-0959, Vol. 32, no 2, p. 433-449Article in journal (Refereed)
    Abstract [en]

    This work proposes the complete design cycle for several auxetic materials where the cycle consists of three steps (i) the design of the micro-architecture, (ii) the manufacturing of the material and (iii) the testing of the material. We use topology optimization via a level-set method and asymptotic homogenization to obtain periodic micro-architectured materials with a prescribed effective elasticity tensor and Poisson’s ratio. The space of admissible micro-architectural shapes that carries orthotropic material symmetry allows to attain shapes with an effective Poisson’s ratio below −1−1. Moreover, the specimens were manufactured using a commercial stereolithography Ember printer and are mechanically tested. The observed displacement and strain fields during tensile testing obtained by digital image correlation match the predictions from the finite element simulations and demonstrate the efficiency of the design cycle.

  • 38.
    Agnelli, Filippo
    et al.
    CNRS, École polytechnique, FRA.
    Nika, Grigor
    Weierstrass Institute for Applied Analysis and Stochastics, DEU.
    Constantinescu, Andrei
    CNRS, École polytechnique, FRA.
    Design of thin micro-architectured panels with extension–bending coupling effects using topology optimization2022In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 391, article id 114496Article in journal (Refereed)
    Abstract [en]

    We design the micro-architecture of thin elastic panels to control their macroscopic behavior, accounting simultaneously for in-plane stiffness, out-of-plane stiffness and the extension–bending coupling effects. Our topology optimization method combines inverse homogenization, the Hadamard shape derivative and a level set method in the diffuse interface context to systematically capture within the unit cell the optimal micro-architecture. The efficiency of the solution method is illustrated through four numerical examples where the designed shape yields an important extension–bending coupling. The deformation responses under tensile loading are assessed numerically both on the complete periodic panel and on its homogenized twin plate. The results demonstrate that the simultaneous control of the in-plane, out-of-plane and their coupled behavior enables to shift a flat panel into a dome or a saddle shaped structure. Moreover, the obtained unit cells are elementary blocks to create directly 3D printable objects with shape-morphing capabilities.

  • 39.
    Ahl, Daniel
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Analysis of how different mesh functions influence the result in CFD-simulation of a marine propeller:  2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 40.
    Ahl, Elin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Nordberg, Nina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Planning a digital transformation for a company with a process layout: A study conducted at voestalpine Precision Strip AB2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Digitalization is an upcoming trend that divides the manufacturing industry of today. As an increasing number of companies chose to implement digitalization as a business strategy, some companies still struggle with implementing digitalization into their businesses.

    Previous research has developed digital transformation models, but has been admitted as too generic. This thesis used the most comprehensive transformation model as base and aimed to make it practically implementable for a manufacturing company with a process layout. To enable this, a case study was conducted on a steel-processing company with this layout design. This thesis had an inductive approach, where primary data were collected from one selected company through a pilot study and semi structured interviews, and secondary data were collected through a literature review.

    During the study, it was discovered that a company can benefit from using a customized guidance of how to implement digitalization, to optimally use digital opportunities. This thesis contributed with additional steps and extensions of the previous transformation model. The contribution consisted of the involvement of competency, creation of definition, identified digitalization trends relating to a SWOT analysis, additional phenomenon to take into consideration when analyzing future scenarios, additional questions to consider when analyzing impacted areas, creation of a digital business strategy, a comparison of impacted areas with previous projects, additional identified actions to fill the gap between current state and goals, and five identified criteria’s on how to prioritize these actions. This study extends current research with details and depth regarding a digital transformation model, and hence make it more practical. For future research, a case study testing the potential of the transformation model on a similar company should be conducted, and thereby improve the model further.

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  • 41.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Arahamsson, Henrik
    RISE SICS.
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Latency-aware Multipath Scheduling inInformation-centric Networks2019In: Proceedings of the Fifteenth Swedish National Computer Networking Workshop (SNCNW), Luleå, Sweden. 4-5 June 2019., 2019Conference paper (Refereed)
    Abstract [en]

    We present the latency-aware multipath schedulerZQTRTT that takes advantage of the multipath opportunities ininformation-centric networking. The goal of the scheduler is touse the (single) lowest latency path for transaction-oriented flows,and use multiple paths for bulk data flows. A new estimatorcalled zero queue time ratio is used for scheduling over multiplepaths. The objective is to distribute the flow over the paths sothat the zero queue time ratio is equal on the paths, that is,so that each path is ‘pushed’ equally hard by the flow withoutcreating unwanted queueing. We make an initial evaluation usingsimulation that shows that the scheduler meets our objectives.

  • 42.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Abrahamsson, Henrik
    RISE SICS.
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Are MIRCC and Rate-based Congestion Control in ICN READY for Variable Link Capacity?2017Conference paper (Other academic)
    Abstract [en]

    Information-centric networking (ICN) has been introduced as a potential future networking architecture. ICN promises an architecture that makes information independent from lo- cation, application, storage, and transportation. Still, it is not without challenges. Notably, there are several outstanding issues regarding congestion control: Since ICN is more or less oblivious to the location of information, it opens up for a single application flow to have several sources, something which blurs the notion of transport flows, and makes it very difficult to employ traditional end-to-end congestion control schemes in these networks. Instead, ICN networks often make use of hop-by-hop congestion control schemes. How- ever, these schemes are also tainted with problems, e.g., several of the proposed ICN congestion controls assume fixed link capacities that are known beforehand. Since this seldom is the case, this paper evaluates the consequences in terms of latency, throughput, and link usage, variable link capacities have on a hop-by-hop congestion control scheme, such as the one employed by the Multipath-aware ICN Rate-based Congestion Control (MIRCC). The evaluation was carried out in the OMNeT++ simulator, and demonstrates how seemingly small variations in link capacity significantly deterio- rate both latency and throughput, and often result in inefficient network link usage. 

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  • 43.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Hurtig, Per
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Abrahamsson, Henrik
    RISE SICS.
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    ICN Congestion Control for Wireless Links2018In: IEEE WCNC 2018 Conference Proceedings / [ed] IEEE, New York: IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    Information-centric networking (ICN) with its design around named-based forwarding and in-network caching holds great promises to become a key architecture for the future Internet. Still, despite its attractiveness, there are many open questions that need to be answered before wireless ICN becomes a reality, not least about its congestion control: Many of the proposed hop-by-hop congestion control schemes assume a fixed and known link capacity, something that rarely – if ever – holds true for wireless links. As a first step, this paper demonstrates that although these congestion control schemes are able to fairly well utilise the available wireless link capacity, they greatly fail to keep the link delay down. In fact, they essentially offer the same link delay as in the case with no hop-by-hop, only end- to-end, congestion control. Secondly, the paper shows that by complementing these congestion control schemes with an easy- to-implement, packet-train link estimator, we reduce the link delay to a level significantly lower than what is obtained with only end-to-end congestion control, while still being able to keep the link utilisation at a high level. 

  • 44.
    Ahlgren, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science.
    Lidström, Joakim
    Karlstad University, Faculty of Technology and Science.
    Gastromax Duo: Ett kompakt rivjärn för den moderna hemmakocken2010Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    ”Gastromax Duo” is a degree project for the Innovation and Design Engineering program at Karlstad University. Joakim Ahlgren and Joakim Lidström have independently carried out the project during Spring Term 2010. The degree project extends 22,5 ECTS credits.

    The assigners for this project are Peter Ottosson and Jonas Eriksson at Sveico AB in Gnosjö, Sweden. Peter Johansson is the project supervisor at Sveico AB and Monica Jacobsson is the academic supervisor at Karlstad University. The examiner at Karlstad University is Lennart Wihk, who has also supported the project team during the design process.

    Sveico AB is located in Gnosjö, Sweden and manufactures kitchen utensils and other kitchen accessories. In the Sveico AB product portfolio resides the Gastromax series of kitchen tools for the ”home chef”. The lack of a foldable grater within the Gastromax series was noticed by the Sveico AB management, which brought about this project.

    The largest part of this project was a very thorough pre-study phase, where the project team mapped out the needs and wishes of the users, along with research about the market of the product. The pre-study consists of interviews with consumers, professional users and representatives of commerce, along with user studies.

    During the product development process, a number of idea generation methods has been used, both internally in the project team and externally with uninitiated individuals. During the subsequent concept generation phase, emphasis was put on the development of physical models, used to evaluate ideas and solutions.

    Out of the 19 concepts that were developed during the concept generation phase, six was chosen through a set of systematic evaluation routines. These six concepts were presented to the assigners that in turn chose two of the concepts for the project team to develop further. These two concepts was then combined and transformed into the final product proposal.

    The final, detailed solution is surrounded with secrecy, but three key concepts in the final foldable grater can be officially stated:

    • A long grating surface
    • Adjustable work angle
    • Two grating surfaces: one fine and one coarse

    The final result of the project is a product description of the grater, with a proposal of a general design, a mechanical solution of the adjustability aspect and a suggestion of materials for the different product components.

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  • 45.
    Ahlin, Viktor
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Awaz, Mohammadullah
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Potentiella tillsatsmaterial i betong: En studie om hur tryckhållfastheten före och efter brand skiljer sig mellan befintliga och potentiella recept2023Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The concrete industry in Sweden accounts for approximately 8 % of the construction sector's carbon dioxide emissions. Of this approximately 1.7 million tons of CO2e annually, about 90 % of the emissions are due to cement production. In order for the use of concrete in the future to be as much as it is today, carbon dioxide emissions need to decrease. This can be accomplished by replacing a proportion of the cement with possible additive materials. Until now, additive materials such as blast furnace slag have been standardized, considering that the supply of this material is expected to be limited; the existing recipes need to be replaced with potential recipes containing newly found additive material.

    The purpose of the study is to investigate, through test compression and fire tests, how the compressive strength is affected by fire for potential concrete recipes compared to existing concrete recipes. The study consisted of two main parts. The first part consisted of a literature study of concrete's environmental impact, the properties of concrete, concrete’s fire properties and possible additive materials in concrete. The second part consisted of a laboratory part, based on standards where casting, test pressing and fire testing were included. Visual observations were also conducted of the cracking after the test pressing. A total of 14 cubes were cast, two of each recipe. The difference shown between the existing recipes 1 and 2 was that Recipe 2 contained 50 % blast furnace slag while Recipe 1 consisted of 100 % building cement. Recipes 3–7were possible recipes, where Recipe 3 replaced 10 % of the cement with biochar; Recipe 4 contained 50 % blast furnace slag and polypropylene fiber (PP fiber); and Recipes 5–7 contained different amounts of hydrochar, i.e. 5 %, 10 % and 20 %, respectively.

    The results showed that the existing recipes had the highest compressive strength, while potential recipes showed better protection against spalling. Recipe 1 had the highest compressive strength before fire testing (53.3 MPa) while Recipe 7 had the lowest (6 MPa). Concrete Recipe 3 had the greatest mass loss as a result of spalling, while Recipe 6, which did not spall, had the least. Recipe 3 had the greatest reduction in compressive strength (83.2 %) when comparing before and after fire tests. The cracking resulting from the compression test became more extensive after the fire test; the cracks were deeper and wider. This more extensive cracking resulted in large parts of the concrete separated from the cube. 

    The conclusions drawn were that the potential additives investigated reduced the compressive strength while strengthening the protection against spalling for Recipes 4–7. Recipe 6 had the best protection against spalling. The greatest compressive strength before fire for the potential recipes had Recipe 3 (38.7 MPa), while after fire Recipe 4 had the highest (7.8 MPa). The largest and smallest reduction of compressive strength post fire had Recipes 3 and 7, respectively. Recipes 3 and 4 met the requirement regarding the compressive strength, Recipes 4, 5, 6 and 7 met the requirement regarding the protection against spalling to be preserved. The cracks after fire were deeper and wider compared to before fire. Overall, the potential recipes had less cracks before fire, but after fire, it was the existing recipes that had fewer cracks.

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  • 46.
    Ahlquist, Ulrika
    Karlstad University, Division for Information Technology.
    Trådlöst elektriskt lås2007Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med examensarbetet är att göra en trådlös version av det elektriska lås som tillverkas av Electec System AB.

    För att göra ett trådlöst elektriskt lås måste ett batteri monteras i låset. Batteriet måste hållas uppladdat hela tiden för att kunna driva motorn och ge strömförsörjning till elektroniken i låset. Alla signaler mellan låset och styrenheten ska dessutom överföras trådlöst istället för med kabel. Signalerna måste kodas innan sändning så att ingen obehörig kan läsa signalen och sedan öppna dörren.

    Det svåraste i ett trådlöst elektriskt lås är att överföra effekt från dörrkarmen till låset eftersom utrymmet är begränsat och avståndet mellan låsblecket i karmen och låset i dörren kan uppgå till 10 mm. För att överföra effekt från dörrkarmen till låset konstruerades en transformator. Förlusterna i transformatorn ökar kraftigt då luftgapet ökas.

    Det visar sig att motor och övriga kretsar kan drivas med ett avstånd mellan kärnorna på upp till 7 mm. Luftgapet kan sannolikt ökas när andra transformatorkärnor används. Dessa fanns dock inte tillgängliga under examensarbetets gång på grund av lång leveranstid. I jämförelse med överföring av effekt är problemet att koda och överföra signaler mellan styrenheten och låset enklare och kan lösas med hjälp av färdiga kretsar.

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  • 47.
    Ahlsten Andersson, Albin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Utformning av hållbar energikälla för fritidsfordon: Att skapa möjlighet för elförsörjning vid naturnära ställplatser2020Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Rapporten innefattar ett examensarbete inom högskoleingenjörsprogrammet i innovationsteknik och design vid Karlstads universitet. Projektet är en del av examinationen och utförs under vårterminen 2020 samt omfattar 22,5 hp. Författare av rapporten är Albin Ahlsten Andersson, handledare på universitet är Lennart Wihk och examinator är Leo de Vin.

    Projektet följer traditionell produktutvecklingsmetodik och utförs med designprocessen som huvudfokus. I projektet ingår följande faser: projektplanering, förstudie, specificering av produkt, kreativ problemlösning, konceptval och konstruktion. Arbetet presenteras i form av en rapport, virtuell utställning, en slutpresentation och opponering.

    Uppdragsgivaren för projektet är Glava Energy Center med Visit Värmland, Glaskogens Naturreservat och Sommerhaus Schweden som oberoende intressenter. Glava energy center är ett utvecklingscentrum beläget i Glava i Värmland, där de arbetar med hållbara lösningar både på nationell och internationell nivå. De oberoende intressenterna hade som roll att förse arbetet med en bredare kompetens inom området, och hjälpa till med frågor gällande främst den värmländska turismen. Enligt uppdragsgivare och intressenter finns det ett behov av naturnära ställplatser med tillgång till elektricitet. Projektet syftar därför på att utveckla en lösning som både är mobil, tillverkad av hållbart material och som smälter in i kringliggande miljö. Produkten skall tillåta användaren att stå i närheten av naturen under en längre tid utan att förlora bekvämligheten av tillgång till elektricitet.

    Efter användarstudie och marknadsanalys konstaterades det att de flesta alternativen som används idag vid fricamping antingen inte är miljövänliga, eller genererar för lite elektricitet för att kunna uppfylla det behov som finns. Enligt svaren på intervjuerna och enkäten fanns det viss problematik med att fricampa under en längre tid då resurser såsom soputrymme, mat och elektricitet sinade. De oberoende intressenterna kunde här också bidra med sin kunskap från det verkliga fallet och ge en tydligare bild av vad för slags behov det kan komma att finnas hos de framtida användarna.

    För att lösa problemet användes kreativ problemlösning både på enskild nivå men också i grupp. Efter denna fas hade tre koncept framkommit som verkade relevanta för fallet. Dessa koncept vägdes mot kravspecifikationens mål och presenterades sedan för uppdragsgivare samt intressenter i ett gatemöte. Det slutgiltiga valet överensstämde med värderingen av koncepten mot projektets önskemål. Konceptet presenteras i form av skisser, CAD-modell och en fysisk modell som huvudsakligen är tillverkad av rundstavar av trä.

    Konceptet är flexibelt och gör det möjligt för producent i framtiden att anpassa den efter vad för dimensioner som önskas. Den är tillverkad av timmerstockar och ger en känsla av friluftsliv samtidigt som det skyddar den ingående tekniken. Genom att fästa strukturen i marken är det också möjligt att hålla strukturen stabil och den vinklade kapningen av stockarna håller solpanelerna i rätt vinkel. Eftersom produkten är tillverkad i moduler är det också enkelt att byta ut delar och underhålla dem.

    Arbetet levererar ett koncept som motsvarar de förväntningar som fanns på projektet, uppfyller dess målsättningar och besvarar problemformuleringarna. Ett fortsatt arbetet krävs dock med bland annat hållfasthetsberäkningar, materialval och undersökning av lagar och regler gällande fricamping.

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  • 48.
    Ahmad, Awais
    et al.
    Mittuniversitetet.
    Ahlin, Karin
    Mittuniversitetet.
    Mozelius, Peter
    Mittuniversitetet.
    Technology-enhanced speech and language relearning for stroke patients: defining requirements for a software application development2020Conference paper (Refereed)
    Abstract [en]

    Speech and language relearning are challenging for stroke survivors as well as for medical caregiv-ers. After a stroke, a patient’s ability to read, write, speak, and listen is decreased to different degrees, which results in a compromised independent life and a decreased quality of life for the patient. Tech-nology enhances systems can play a vital role in this context. However, the available software are not specifically built for after the stroke patient’s needs. This paper is therefore aimed to gather require-ments for designing a tailor-made speech relearning software application for stroke survivors. A de-sign science approach was adopted, where different stakeholders such as medical caregivers and in-formation technology consultants were involved in the process. The well-informed and experienced participants in their fields highlighted some important requirements such as different types of inter-face for a patient than speech therapist with extra management functionality for speech therapists so that they can adjust the relearning exercises according to the patient’s needs. Software requirements vary from patient to patient where the intensity of speech and language impairments, general medical condition of the patient, age, prior experience, and knowledge about the information of the patient and social setup of the patient plays an important role. Since stroke is most common in adults and adults learn differently than children, adult learning theory might help understand the patients’ needs. There-fore, adult learning principles were involved in the requirement analysis process. The established re-quirements will be used for the development of speech and language relearning software.

  • 49.
    Ahmad, Muhammad Ovais
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Psychological Safety, Leadership and Non-Technical Debt in Large Scale Agile Software Development2023In: Proceedings of the 18th Conference on Computer Science and Intelligence Systems, FedCSIS 2023, Poland: Institute of Electrical and Electronics Engineers (IEEE), 2023, p. 327-334Conference paper (Refereed)
    Abstract [en]

    Psychological safety has been hypothesised as an important antecedent of the success of agile software development (ASD) teams. However, there is a lack of investigation on psychological safety in large-scale agile (LSA) software development teams. This study explored the antecedents and effects of psychological safety on LSA teams. We conducted semi-structured interviews with software professionals working on LSA project in a Scandinavian technology company. The results suggest that building a psychologically safe environment is a multi-dimensional factor that requires proactive leadership approach, open communication and constructive feedback. The focus should be on designing teams for learning, remuneration safety, and a well-prepared onboarding process for new team members. A psychologically safe environment contributes to effective teamwork, work satisfaction, and promotion of learning. Absence of such an environment leads to brain drain, highlighting the consequences of neglecting this essential aspect of organisational culture. Future research directions are proposed in this paper.

  • 50.
    ahmad, waqas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Development of algorithm for li-ion batteries in electric vehicles, taking into account SOC, charge control, cell balancing and SOF.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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