Publikationer från Linköpings universitet
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Modeling and Control of Slip Ratio to Maximize Tractive Force for Electric Trucks
No full textThis thesis explores how to maximize traction for battery electric heavy-duty trucks under challenging road conditions. On road surfaces with low grip, requesting a high torque from the electric motor can lead to excessive slip and reduction of tractive force as a consequence. The aim of this thesis is to implement a control strategy that regulates the torque to achieve maximum tractive force between the wheels and the road surface. This is done by using a gradient ascent method and iteratively looking at estimates of the driveshaft torsion and rotational speed of the electric motor and the wheels to find the peak of the friction coefficient-slip ratio curve, that describes the relation between slip and the friction coefficient. A reference generator is developed, outputting a reference in slip ratio for the controller to follow, directing it towards the peak of the friction coefficient-slip ratio curve. Two types of controllers are tested, PI controller and an LQR controller. As the dynamics of the driveline differ for each gear, the controllers where tuned differently at each gear. PI controllers are the ones used for the majority of the simulations. The performance of the reference generator and the controllers are evaluated using simulations in Matlab/Simulink where the driveline model has been implemented. The results show that the control framework is able to find and stay at the maximum tractive force in multiple simulation configurations. The drawback of the gradient ascent method is its sensitivity to noise and future work should include better and more reliable ways to filter and estimate states and signals.
Carbon Coatings for Bipolar Plates in Proton Exchange Membrane Fuel Cells : Microstructure, Functional Properties, and Fuel Cell Requirements
No full textAmorphous carbon coatings show great promise for metallic bipolar plates in proton exchange membrane fuel cells. Due to the diverse bonds of carbon, the thin films can achieve a wide range of properties, including excellent electrical conductivity and corrosion resistance. In this study, different sets of carbon coatings were synthesized on 316L stainless steel sheets using direct current magnetron sputtering. This thesis investigated the effect of different sputtering parameters, carbon bonding characteristics, and film thicknesses on the functional properties and production feasibility. The samples were characterized by scanning electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, and X-ray reflectivity. The performance of the coatings was evaluated through electrochemical corrosion tests as well as interfacial contact resistance measurements before and after the corrosion tests. The results showed that the amorphous carbon coatings significantly improve the performance of the bare 316L stainless steel substrate. The SEM images revealed a relatively compact and dense microstructure with island growth and noticeable surface roughness. Raman spectra demonstrated clear correlations between the carbon bonding characteristics and the interfacial contact resistance. The results showed that the larger the ID/IG-ratio, the lower the ICR value. The overall best performing sample achieved an initial interfacial contact resistance of 4.68 mΩ cm2 and a current density of 0.305 µA/cm2 in the potentiostatic polarization (at +0.6 V vs Ag/AgCl for 24 h). The values met the industrial requirements for bipolar plates, defined by the US Department of Energy. However, the coating failed to satisfy the criteria in the potentiodynamic polarization, exhibiting a current density of 2.975 µA/cm2 at +0.6 V (vs Ag/AgCl). Furthermore, the ICR significantly increased after the corrosion tests to a value of 25.97 mΩ cm2. Analysis by SEM and EDX after corrosion tests revealed that the thin film underwent structural changes in the surface morphology and elemental composition. Thus, future investigations are needed to densify the carbon coating microstructure and enhance the anti-corrosive properties
”Vi kör ju vårat race bara i ett annat land.” : En kvalitativ studie om meningsskapande processer bland svenskar bosatta i Spanien
No full textDenna kandidatuppsats undersöker meningsskapande processer bland svenskar bosatta i södra Spanien, med särskilt fokus på hur ålder och upplevd "svenskhet" påverkar vardagslivet. Genom en kvalitativ intervjustudie med sex informanter i olika åldrar analyseras hur dessa individer konstruerar sin tillvaro i ett transnationellt sammanhang. Tidigare forskning visar ett särskilt fokus på pensionärer, i denna studie breddas perspektivet genom att fokusera på svenska migranter i åldrarna 20-55 år. Studien bygger på teorier om transnationalism och identitet som diskursiv process, med ambitionen att nyansera bilden av "Spaniensvenskar" som en homogen grupp. Resultaten visar att informanterna navigerar mellan svensk och spansk kontext genom sociala nätverk, kulturella uttryck och föreställningar om livskvalitet. Migrationen framstår som en strategi för självförverkligande där livsstil, trygghet och individuell frihet spelar centrala roller. Studien visar att "svenskhet" är en föränderlig och situationsbunden identitet, som omförhandlas i det nya sammanhanget. Resultatet indikerar att informanterna utgör en migrationsgrupp med betydande valmöjligheter som tycks prägla deras tillvaro. Genom att inkludera olika åldersgrupper bidrar uppsatsen till en mer komplex förståelse av svensk livsstilsmigration, där meningsskapande processer formas av både personliga erfarenheter och samhälleliga strukturer.
Tillväxt och demografi : En kvalitativ undersökning av Norrköpings kommunpolitikers syn på den samtida och framtida välfärden
No full textThis paper explores how municipal politicians in Norrköping view issues concerning efficiency, demography and growth and how these issues relate to welfare. The empirical data has been collected through semi-structured focus group interviews with 6 of the leading political parties in Norrköping. With a theoretical background of new public management, feminist economic theory and modern monetary theory, the paper aims to answer the question of how Norrköping municipal politicians view welfare now and in the future. The conclusions of the paper are that there is a consensus about welfare as important for a functioning society. At the same time, welfare is considered an expenditure and should be streamlined in accordance with new public management. According to the municipal politicians, growth is a prerequisite for welfare both now and in the future. In the final discussion of the paper, growth is problematized from a climate perspective. We can see that the municipality's politicians believe that immigration is a prerequisite for fulfilling the welfare mission. We can also see that while local politicians place their hope in immigration for the execution of welfare services, politicians on a national level see immigration as a financial burden that needs to be limited. That discrepancy on immigration is discussed from the view of modern monetary theory
Simuleringsbaserad träning i katastrofmedicin : En analys av pedagogik, kognitiv fidelitet och instruktörers erfarenheter
No full textThis thesis explores the application of simulation-based training in disaster medicine, with a specific focus on cognitive fidelity and the experiential learning cycle. Conducted as a qualitative study at the Center of Disaster Medicine and Traumatology (KMC) in Linköping, Sweden, the research examines how different simulators support the learning processes of participants and if they engage cognitive processes relevant to micro- and macro cognition, such as stress, problem- solving decision-making and memory load. The study investigates how simulation at KMC align with the four concepts in the learning cycles (Experiencing, Reflecting, Thinking and Acting), as well as which cognitive processes the educators perceive are used in the simulations. Data was collected at six different observation points during courses at KMC (including Stop The Bleed, Tactical Emergency Casualty Care, Tactical Combat Casualty Care, Emergo Train System, Casualty Scene Collaboration and Special Care Management) as well as during five semi structured interviews with course instructors. The analysis included a deductive content analysis and a thematic analysis to evaluate both the theoretical application of Kolb’s model and the practical challenges and advantages of simulators identified by the educators. The findings indicate that simulation training at KMC supports multiple stages of the learning cycle, particularly acting and experiencing as well as reflecting and thinking, through the hands- on experience and the reflecting generated in the After Action Reviews. While many simulators provided valuable opportunities for skill acquisition and rehearsal under realistic environments, some limitations were noted in terms of cognitive fidelity. Educators highlighted both strengths, such as the engagement, safe learning environments and visualization of logistics, and challenges such as technological limitations, varying levels of realism and cost with the use of simulators. The study concludes that simulation-based educators in disaster medicine benefits form aligning the education with cognitive and pedagogical models, and that an increased cognitive fidelity (especially at a macro level) may improve the preparedness of healthcare workers at a more professional level. The results offer insights into how simulation tools can be re-worked to better support and enhance the education in disaster medicine.
No cause for concern? : A Study on the Path of Dairy Actors Toward Organic and Economic Sustainability
No full textDen svenska mjölkmarknaden har utsatts för ökad konkurrens och omfattande strukturomvandlingar efter EU-inträdet som även medfört skärpt krav på hållbart jordbruk. Med bakgrund mot detta väcks frågan om hållbarhet, lönsamhet och olika mjölkaktörers strategier kan studeras för att förstå omställningen mot en svensk hållbar mjölkproduktion. Den svenska mjölkmarknaden har beskrivits från ko till bord, där uppvisat resultat belyser oligopol med stora aktörer som dominerar marknaden i respektive led. Vidare syftar uppsatsen till att analysera hur EU:s nya jordbruksersättningar har haft en påverkan på de svenska mjölkaktörernas strategier och om jordbruksersättningar är ett effektivt styrmedel för att uppnå en hållbar och lönsam svensk mjölkproduktion. Baserat på en kvalitativ analys med utgångspunkt i sekundärdata från myndigheter, företag och EU har vi applicerat SCP-modellen för att bättre förstå och analysera den svenska mjölkmarknaden samt mjölkaktörernas strategier. Vidare jämföras Arla och Skånemejeriers strategier baserat på deras rapporter, uttalanden och uppvisade resultat i förhållande till deras mål. Resultatet visar att EU har en avsevärd påverkan på den svenska mjölkmarknaden och jordbruksersättningar utgör en viktig del för en lönsam mjölkproduktion. Vidare är det för tidigt att utvärdera de nya jordbruksersättningarna, i och med att hållbarhet är komplext att mäta och effekten ännu inte är fastställd eftersom konsekvenserna på miljön är fördröjda. Arla och Skånemejerier arbetar strategiskt för att verka för en hållbar mjölkproduktion med visioner om bland annat fossilfria och klimatneutrala verksamheter. Respektive strategier för en hållbar mjölkproduktion kan ifrågasättas då ekologisk produktion minskat sedan 2020 trots de positiva externa effekterna som ekologisk produktion bidrar med. Vi kan varken fastställa eller utesluta om hållbarhet för verksamheterna går hand i hand med lönsamhet. För att besvara relationen mellan hållbarhet och lönsamhet inom den svenska mjölkproduktion krävs vidare forskning.The Swedish market for milk has undergone increased competition and significant structural changes following EU accession, leading to stricter demands for sustainable agriculture. Against this background, the question arises whether sustainability, profitability, and the strategies of various milk actors can be studied to better understand the transition toward sustainable milk production in Sweden. The Swedish milk market has been outlined, where the findings highlight an oligopolistic structure dominated by large actors. Furthermore, this thesis aims to analyze how the EU's new agricultural subsidies have influenced the strategies of Swedish milk actors, and whether these subsidies serve as an effective policy instrument for achieving a sustainable and profitable Swedish milk production. Based on a qualitative analysis grounded in secondary data from public authorities, companies, and the EU, we apply the SCP-model to better understand and analyze the Swedish milk market and the strategies of the key actors. Additionally, we compare the strategies of Arla and Skånemejerier based on their reports, public statements, and performance in relation to their stated goals. The results show that the EU has a significant influence on the Swedish milk market, and that agricultural subsidies play a vital role in maintaining profitability. However, it is too early to evaluate the impact of the new subsidy schemes, as sustainability is inherently complex to measure and environmental effects are delayed. Arla and Skånemejerier pursue strategic efforts toward sustainable dairy production, with visions including fossil-free and climate-neutral operations. Respective sustainability strategies are questionable, as organic production has declined since 2020, despite the positive externalities it provides. We are unable to conclusively determine whether sustainability aligns with profitability in their operations. Further research is needed to fully understand the relationship between sustainability and profitability in Swedish milk production
Contested Public Space in Urban Redevelopment : A Critical Discourse Analysis of Potsdamer Platz and Tempelhofer Feld
No full textThis study investigates how governance processes around public space developments in Berlin have been discursively shaped, with particular attention to the redevelopment of Potsdamer Platz in the 1990s and Tempelhofer Feld in the early 200s around the time of the former airport’s closure in 2008. The study employs a Critical Discourse Analysis to examine how language, narratives, and framing strategies have been used to legitimise urban development and reflect broader tensions concerning publicness, privatisation, and urban democracy. The findings demonstrate that the redevelopment of Potsdamer Platz was characterised by investor-influenced governance, urgency narratives, and the marginalisation of public participation. In contrast, the discourse around Tempelhofer Feld was centred on social justice, and collective rights, fostering more participatory planning forms while remaining contested under neoliberal pressure. Across both cases, discursive strategies emerge as central instrument of governance, showing who is involved in urban development and how the city is imagined, negotiated, and claimed. The study underscores the political nature of urban planning, highlighting the need of critical research on whose visions shape urban areas and for whom the city is made
Framing Value in Infrastructure : Assessing the Potential Impact of the Elevated Railway in Norrköping
No full textThis study aims to systematically explore the proposed construction of a new railway and railway station in Norrköping, Sweden focusing on both the justificatory elements and the project's anticipated effects. Using a combined method of qualitative content analysis and interviews, eleven relevant documents are analysed alongside four concluding interviewswith the project's key stakeholders. The framework of the Swedish Transport Administration(Trafikverket)'s overall impact assessment, Samlad Effektbedömning (SEB), guides theanalysis, which is designed to provide a structured and summarised account of the proposed transport measures.This study interprets the empirical material using the three main components of SEB: socio-economic cost-benefit analysis, transport policy goal objective analysis, and distributionalanalysis. The analysis and discussion are conducted from a social science perspective,supported by previous research and the theoretical framework consisting of WelfareEconomics and Network Governance.Central to the case is the Municipality of Norrrköping's decision to invest an additional SEK2.7 billion in an elevated railway alternative, in contrast to Trafikverket's initial SEK 900million ground-level proposal. The findings show that socio-economic justification is notobtained from quantified calculations but discursively constructed through local actors'strategic framing. Stakeholders emphasise long-term urban development, symbolic value, and regional connectivity. While the project aligns with national transport policy goals, it also reveals tensions in multi-level governance and risks of spatial inequality. The studyconcludes that socio-economic evaluations lack transparency, national goals are locallyreframed, and equity considerations remain limited in planning, highlighting key gaps ininfrastructure governance and justification
Digital tools in audit and their impact on audit quality
No full textBakgrund: Digitalisering är en central del av samhällets infrastruktur idag. Revisionen är inte ett undantag, det har skett en förändring från manuell och traditionell revision till en ökande digital sådan. Vid en ökande digitalisering uppstår utmaningar i efterlevnaden av regler, standarder och praxis. I takt med utvecklingen är det viktigt att revisorn utvidgar sina kunskaper i hanteringen av digitala verktyg för att säkerställa en god revisionskvalitet. Det finns begränsad forskning om hur digitala verktyg används i revisionen, hur det påverkar revisionskvalitet och revisorns arbete, samt vilka utmaningar som revisionen har framför sig. Denna uppsats vill bidra med mer kunskap om hur digitala verktyg och AI implementeras i revisionsprofessionen. Syfte: Syftet med denna studie är att undersöka hur revisorerna i dagsläget tillämpar AI och andra digitala verktyg i revisionsprocessen samt hur dessa påverkar revisionskvaliteten. Metod: Uppsatsen baseras på en kvalitativ forskningsstrategi där det har utförts semistrukturerade intervjuer för att samla in det empiriska materialet. Analysen genomförs med en deduktiv ansats med induktiva inslag. Slutsats: Uppsatsens resultat visar att revisionsprocessen befinner sig under en stor digital omvandling. Empirin visar att digitala verktyg används genom hela revisionsprocessen med tyngdpunkt i planerings- och granskningsfaserna. Digitaliseringen och AI har påverkat revisionsprocessen och revisionskvaliteten positivt genom ökad standardisering, effektivisering och noggrannhet. Uppsatsen visar också att det finns utmaningar som exempelvis fortsatt professionell skepsis, teknisk förståelse och kundkännedom.Introduction: Digitalisation is a central component of today's societal infrastructure. Auditing is no exception - there has been a shift from manual and traditional auditing to an increasingly digital approach. As digitalization progresses, challenges arise in complying with regulations, standards, and established practices. In line with these developments , it is important for auditors to broaden their knowledge on handling digital tools to ensure high-quality audits. Research on how digital tools are used in auditing, their impact on audit quality and the auditor´s work, as well as the challenges facing the profession, is limited. This thesis aims to contribute further knowledge regarding the implementation of digital tools and AI within the auditing profession. Purpose: The purpose of this study is to investigate how auditors currently apply AI and other digital tools in the audit process, and how these affect audit quality. Method: The paper is based on a qualitative research strategy in which semi-structured interviews were conducted to collect the empirical data.The analysis is carried out using a deductive approach with inductive elements. Conclusion: The results of the thesis show that the audit process is undergoing a significant digital transformation. Empirical evidence indicates that digital tools are utilized throughout the entire audit process, with a particular emphasis on the planning and review stages. Digitalization and AI have positively influenced both the audit process and audit quality through increased standardization, efficiency, and accuracy. The paper also demonstrates that there are challenges, such as continued professional skepticism, technical understanding, and client knowledge
Associering, spårning och lokalisering av Bluetooth enheter
No full textBluetooth Low Energy (BLE) devices have become integral to modern wireless com munication, facilitating a wide range of applications in consumer electronics, healthcare, security, and beyond. Their capacity to broadcast signals presents significant opportunities for tracking and localization, which could be helpful in domains such as search and rescue operations. However, privacy mechanisms, particularly randomization of Media Access Control (MAC) addresses, pose substantial challenges to persistent device identification and tracking. This thesis explores methodologies for associating BLE measurements with specific devices and estimating their locations, despite the complexities introduced by privacy preserving techniques. By developing robust association and localization frameworks, this study aims to advance BLE-based tracking applications while addressing the inher ent trade-offs between utility and privacy. The methodological framework is empirical and based on BLE signal measurements collected through scanning equipment deployed in both controlled tests and outdoor field conditions. The process begins with identifying unique MAC addresses and extracting rel evant features. These features feed into an association algorithm that attempts to associate individual measurements with specific physical targets despite the address randomization. Alocalization algorithm is then used to estimate the position of each target by combining Received Signal Strength Indicator (RSSI) data with the known locations of the scanners. Both algorithms are validated against ground truth data using reference devices and RSSI f iltering. Association and localization are central to this tracking method: association ensures that fragmented or randomized measurements are correctly grouped per physical device, while localization estimates where each target was at a given time. The output of the methodisaspatiotemporal trace of each tracked device, providing a sequence of estimated positions that can aid in real-time tracking or retrospective analysis. Theassociation algorithm is capable of grouping signal observations from the same de vice, although its accuracy is affected by timing inconsistencies. Localization, based on sig nal strength data, generally performs well when scanners are spatially distributed but can suffer in certain geometric configurations. Adjustments in scanner placement and tempo ral processing show potential to improve association reliability and localization accuracy. While the approach is promising for static or semi-static scenarios, further adaptation is needed for use in dynamic, real-time search and rescue operations.Bluetooth Low Energy (BLE)-enheter har blivit en integrerad del av modern trådlös kommunikation och möjliggör ett brett spektrum av tillämpningar inom konsumentelektronik, hälso- och sjukvård, säkerhet och andra områden. Deras förmåga att sända signaler erbjuder betydande möjligheter för spårning och lokalisering, vilket kan vara särskilt användbart inom exempelvis sök- och räddningsinsatser. Emellertid utgör integritetsskyddande mekanismer, särskilt randomisering av Media Access Control (MAC)-adresser, avsevärda utmaningar för beständig identifiering och spårning av enheter. Denna avhandling undersöker metoder för att koppla BLE-mätningar till specifika enheter samt uppskatta deras positioner, trots de komplexiteter som introduceras genom integritetsbevarande tekniker. Genom att utveckla robusta ramverk för association och lokalisering syftar studien till att främja BLE-baserade spårningstillämpningar, samtidigt som de inneboende avvägningarna mellan nytta och integritet beaktas. Det metodologiska ramverket är empiriskt och baseras på BLE-signalmätningar insamlade med hjälp av skanningsutrustning som har distribuerats i både kontrollerade tester och i fältmiljöer utomhus. Processen inleds med identifiering av unika MAC-adresser och extraktion av relevanta egenskaper. Dessa egenskaper matas in i en associationsalgoritm som försöker koppla enskilda mätningar till specifika fysiska mål, trots adressernas randomisering. En lokaliseringsalgoritm används därefter för att uppskatta varje måls position genom att kombinera data från mottagen signalstyrka (Received Signal Strength Indicator, RSSI) med de kända positionerna för skannrarna. Båda algoritmerna valideras mot referensdata med hjälp av referensenheter och RSSI-filtrering. Association och lokalisering utgör centrala komponenter i denna spårningsmetod: association säkerställer att fragmenterade eller randomiserade mätningar korrekt grupperas per fysisk enhet, medan lokalisering uppskattar var varje mål befann sig vid en given tidpunkt. Metodens utdata är ett rumsligt-temporalt spår för varje spårad enhet, vilket ger en sekvens av uppskattade positioner som kan användas för realtidsuppföljning eller retrospektiv analys. Associationsalgoritmen har förmåga att gruppera signalobservationer från samma enhet, även om dess noggrannhet påverkas av tidsmässiga inkonsekvenser. Lokaliseringen, som bygger på signalstyrkebaserad data, fungerar i allmänhet väl när skannrarna är rumsligt utspridda, men kan uppvisa svårigheter i vissa geometriska konfigurationer. Justeringar av skannrarnas placering samt temporala processer visar potential att förbättra både associationsnoggrannhet och lokaliseringsprecision. Även om metoden är lovande för statiska eller semi-statiska scenarier, krävs ytterligare anpassningar för att kunna användas i dynamiska, realtidsbaserade sök- och räddningsoperationer