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There is a growing intent among engineers, stakeholders, and decision makers to use probabilistic methods for infrastructure assessment or design objectives. However, the corresponding limit state for such problems usually requires the construction of complex computational models, usually using commercial software without parallelization capability. Such a requirement makes performing reliability analysis computationally prohibitive, which is even more challenging for dynamic problems, since a very short time step is required to obtain sufficiently accurate predictions. This concern has led to several methods being proposed to surrogate the limit state function with a generally black box called a meta-model. A variety of them, such as Kriging, Polynomial Chaos Expansion (PCE), Artificial Neural Networks (ANN), and response surfaces (e.g., polynomial, spline, or radial-base functions), have been adopted for this purpose. These meta-models are typically trained on a limited data set collected by computing the true responses of carefully selected input variables. Their applicability for assessing the probability of failure has been studied individually in the literature for both benchmark and practical problems. However, as far as the authors are aware, no comparison has been made between them for dynamic problems. This comparison needs to be made from the point of view of both accuracy and performance (number of calls to the limit state function). In this context, this paper takes a systematic approach to evaluate their performance under identical conditions, i.e., with similar training datasets. For this purpose, the dynamic response of railway bridges with different spans excited by the passage of trains with a wide range of speeds is used as a reference problem., QC 20231004

High-speed railway is expanding drastically in Sweden, necessitating new technology, and improve-ments of existing structures. End-shield bridges are a common and under-tested bridge type inSweden. Their dynamic performance is significantly impacted by their boundary conditions due to thesoil–structure interaction (SSI) and their large masses cantilevering beyond the footings. A specificend-shield bridge was tested under low (5 kN) and high (20kN) amplitude-forced hydraulic excitationfor a wide range of frequencies. Several train passages for typical passenger trains,‘X62’, were meas-ured with the same experimental setup. The results were analysed to isolate the significant modes ofthe system and the natural frequencies. A full 3D numerical model was calibrated and updated inAbaqus, along with a brief sensitivity study to determine the most influential parameters. Finally, theresponse to passing trains and Eurocode design HSLM trains was calculated. The experimental studyshowed that higher loading amplitudes resulted in higher damping and lower natural frequencies. Thenumerical analysis showed that for this bridge type the SSI cannot be neglected and can be success-fully introduced in the model., QC 20240228

This paper studies analytically the steady state response of the generalised coupled modulated pedestrian-beam system. Pedestrians are considered as modulated spring–mass–damper systems with and without a partially attached mass to the structural system. The governing non-dimensional parameters that defined the system's behaviour are found in an analytical framework. An application of the expression is developed, and a parametric analysis is presented considering a reference pedestrian. The frequency shift effect and the dynamic amplification factor, DAFHSI, of the coupled pedestrian-beam system are characterised. The main contribution of this paper is to provide a closed-form solution of the generalised coupled modulated pedestrian-beam system. This solution can consider any distribution of pedestrians and any definition of the pedestrian SDOF properties. A simple and representative example is presented to demonstrate the utility of the found expression in the context of footbridge dynamics., QC 20231006

This study examines what it means to be a Russian LGBTQ emigrant in light of Russia's invasion of Ukraine in 2022. The study follows a phenomenological research approach that differs from the commonly used scientific approach that strives for objective knowledge. Through a qualitative study consisting of 5 participants who identify themselves as Russian LGBTQ emigrants, this research examines findings via affect theory, queer theory, and theories of social and cultural trauma to ask what it means to be a Russian LGBTQ emigrant, how the LGBTQ emigrant is constructed, and how the construct of being a Russian LGBTQ emigrant affects the subject. The study shows how the meaning of being a Russian LGBTQ emigrant is constructed through the effects of affect and how these effects create a collective, social, and cultural trauma that manifests in their everyday lived experiences while shaping their prospects for the future., 2023-09-14

Electromagnetic disturbance can be detrimental to the performance of a radio communication system, and in today’s society where more and more electronic devices are present in our everyday life it is increasingly vital to consider man-made interference. A communication system can take into consideration the noise characteristics and by doing so will excel in such areas, however, this follows that the algorithms utilized in such systems are more computationally complex and are therefore slow. This master thesis aims to explore the possibility of a neural network-based solution that reaches the same accuracy, as existing methods, but more quickly. Numerous different existing model alternatives have been explored and a plethora of different improvement techniques have been outlined. Two models, Hannet and Lannet, have been designed and improved to enable adaptive demodulation both including or excluding decoding at the receiver in an end-to-end communication system. The evaluation results demonstrate that the proposed models are comparable and in some cases even more accurate than current standardized methods. However, the models are unable to fully learn the decoding algorithms present in the experiments. Thus even though demodulation by itself thrives, performing decoding in conjunction with demodulation is out of reach for these models.

Uppsala Kommun is developing a new city district called Sydöstra staden (SÖS) as an innovative and transformative city district. A technical supply system that aligns with the district’s goals is pyrolysis. Pyrolysis is a process where biomass is heated without the supply of oxygen. This leads to carbonization where the energy is converted to biochar and heated gas that can be used for district heating. The biochar, which is considered as a carbon sink, could be the path for the municipality to achieve their climate goals for 2050. The aim of this project is to investigate the viability of providing district heating to SÖS through pyrolysis. Three scenarios based on biomass assets of garden waste, manure, and wooden chips will be evaluated from four perspectives: climate impact, economic feasibility, district heating coverage, and placement considerations. The method is a model constructed in python that simulates how much heat and biochar that can be produced including an income statement and how the price of biochar relates to the return of investment. The biochar price and biomass flow are two parameters that are examined in the sensitivity analysis. The model enables comparisons between the outcomes of the pyrolysis process and the heat energy demands in SÖS, the biochar usage in Uppsala and the municipality’s CO2 emissions. The results show profitable reactor alternatives in all three scenarios even without selling CORCs. However, the profitability is heavily reliant on maximizing the utilization of burned biomass. Furthermore, the first two scenarios had a negligible climate impact while the most profitable reactor in scenario 3 had a large impact on the municipality’s climate goals. Also, the coverage of district heating has been evaluated due to the asset of biomass as well as placement requirements have been stated.

This study focuses on social class in Swedish EFL coursebooks. The aim is to investigate what different social classes are represented and how much space they are given, as well as how they are portrayed in three Swedish EFL coursebooks aimed at English 5 for upper secondary school. The selected coursebooks Viewpoints 1, Blueprint A 3.0, and Pioneer 1 have been analyzed using qualitative content analysis, focusing on texts and images presented in the materials. The analysis emanates from Neo-Marxist theory in order to point to different social class conditions. The results show lower-, middle-, and upper-class representation to various degrees. Mostly the lower class and upper class are visible, while the middle class is underrepresented. The lower class, in most cases, is shown together with the upper class in exploitative circumstances. This is made apparent through the lower class, in most cases, lacking the ability to decide for themselves in relation to their upper-class counterparts. Further, this indicates that the upper class rules the world on behalf of the lower class. Meanwhile, when the middle class is shown, they are mainly depicted through overconsumption, and as victims of upper-class dominance. Despite previous research showing the importance of social class on a global, European and Swedish scale, the coursebooks somewhat disregard its importance in different texts and images.

The fourth industrial revolution also known as Industry 4.0 ushers in new advanced manufacturing technologies that enables companies to improve efficiency and reduce waste. The promising outlook of this era suggests that the implementation degree for Swedish manufacturing SMEs operating in a high-tech context should be high, this is however not empirically observed. The purpose of the paper is to investigate the implementation level of Industry 4.0 technologies in the chosen context, identify barriers that hinder implementation, as well as investigate how the use of the new technologies can be increased. The paper uses a quantitative data approach, using empirical data derived from a survey that was sent out to relevant practitioners acting in the manufacturing industry. Findings indicate that the barriers derived from previous literature match what is experienced by the practitioners surveyed, but that the perceived impact between each barrier is varied depending on if they have implemented Industry 4.0 or not. By combining key themes and findings of the paper, a model is constructed and applied to reduce the perceived impact of the barriers leading to higher implementation levels of new advanced technologies.

Detta examensarbete utvärderar ett absorptionshämmande tillsatsmedel för att möjliggöra användningen av krävande ballast vid betongtillverkning. Den huvudsakliga anledningen till att ballasten benämns som krävande är att den har ovanligt hög absorptionsförmåga. Studien undersöker hur betongens egenskaper påverkas av olika halter absorptionshämmare. Dels studerades glimmerrikt bergkrossmaterial, som på grund av sin höga halt glimmermineral har en hög vattenabsorption vilket försämrar betongens arbetbarhet. För att minska transportavstånd och därmed klimatpåverkan är det viktigt att kunna använda närliggande täkter, även om bergmaterialet innehåller glimmermineral. Utöver glimmerkrossen studerades även återvunnen betong som ballast. Återvunnen betong har också en hög vattenabsorption vilket är en av de största utmaningarna för att kunna använda det som ballastmaterial. Då betong sällan hanteras cirkulärt i byggprocessen utan ofta läggs på deponi är den återvunna betongen som ballast en intressant tillämpning för att öka den cirkulära användningen. Den största delen av arbetet bestod av en laborativ del där den färska betongens egenskaper, såsom sättmått och värmeutveckling, och den hårdnade betongens egenskaper, såsom tryckhållfasthet, utvärderades hos betongen med krävande ballastmaterial och olika halt absorptionshämmare. För den glimmerrika bergkrossen varierades även vattencementtalet, och för återvunnen betong varierades halt återvunnen betong medan vattencementtalet var konstant. En del av arbetet bestod av en teoridel där standarder och krav kring användning av återvunnen betong som ballast utreddes. Resultatet från studien visade generellt att absorptionshämmaren förbättrar arbetbarheten hos betongen. Dock gav absorptionshämmaren en svagt retarderande effekt på hårdnandet, vilket syntes både i kalorimetrimätningarna av värmeutveckling och i tryckhållfastheten efter 24 tim-mar. Efter 28 dygn fanns inga tecken på retardation från absorptionshämmare. Gällande sta, This master thesis evaluates an absorption-inhibiting admixture to enable the use of demanding aggregate materials in concrete production. This was achieved by investigating how the properties of concrete were affected by different levels of absorption inhibitor. Firstly, mica-rich aggre-gate material was studied, which, due to its high mica mineral content, has a high water absorption rate that impairs the workability of concrete. In some locations, aggregates need to be transported over long distances. To reduce environmental impact and transportation costs, it is desirable to be able to use nearby quarries, even if the rock material contains mica minerals. In addition to mica aggregate, recycled concrete was also studied as an aggregate. Recycled concrete also has high water absorption, which is one of the biggest challenges in using it as an aggregate material. Since concrete is rarely handled in a circular manner in the construction process and is often disposed of in landfills, using recycled concrete as aggregate is an interesting application to increase its circular utilization. Most of the work in this project consisted of a laboratory part where fresh properties such as slump and heat development, as well as hardened properties such as compressive strength, were evaluated for concrete with demanding aggregate materials and different concentrations of the absorption inhibitor. For the mica-rich rock aggregate, the water-cement-ratio was varied along with the concentration of the absorption inhibitor. For recycled concrete, the concentration of both the absorption inhibitor and the recycled concrete itself were varied while keeping other variables constant. A theoretical part of the work focused on investigating Swedish standards and requirements related to the use of recycled concrete as aggregates. The results of the study generally showed that the absorption inhibitor improved the workability of concrete. However, the absorption inhibitor had a slightly r, Denna studie visar att användningen av återvunnen betong och krossat berg med vattenuppsugande egenskaper kan öka i betongtillverkningen om dessa behandlas med ett medel som förhindrar vattenuppsugningen. Detta är fördelaktigt då mindre betong behöver läggas på deponi och transportutsläppen kommer minska då fler täkter med krossat berg kan användas. Betongindustrin står för ett flertal utmaningar i och med att kraven på minskade utsläpp skärps för att uppnå klimatmålen. Betong tillverkas idag av cement, vatten och stenmaterial, som också kallas ballast. Minskningen av cementproduktionens stora utsläpp är på god väg med metoder som koldioxidinfångning och ersättning av en del av cementet med mer klimatvänliga alternativ. Ballasten, som både återvunnen betong och krossat berg kan användas som, har länge bortprioriterats men blir nu allt viktigare att hantera ur klimatsynpunkt. I Sverige är betonghus vanliga, och när dessa hus ska rivas hamnar betongen oftast på tippen. Ibland blir betong också över från gjutningar. Sådan betong hälls ut för att stelna och användningen av den är begränsad. Helt enkelt finns mycket betong utan användningsområde. Genom att ersätta en del av stenmaterialet i betong med återvunnen betong ökar den cirkulära användningen av betongen vilket ligger i linje med klimatmålen. Svårigheten med materialet är dock att det absorberar mycket fukt vilket ger en trög betong. Oftast används krossad sten som ballast i betong. Beroende på varifrån stenmaterialet kommer har det olika innehåll. På vissa ställen innehåller berget mineralet glimmer som gör att stenmaterialet suger upp mycket vatten. Om användning av berg som innehåller glimmer kan möjliggöras innebär det att transportutsläppen för ballast kan minska då fler bergtäkter kan användas. Detta är viktigt då det är stora volymer stenmaterial som krävs i betongen, och därför stora lass som transporteras. I studien har betong gjutits dels med krossat berg med glimmermineral, dels med återvunnen betong.

Operating high-speed trains imposes excessive vibrations to bridges raising concerns about their safety. In this context, it was shown that some conventional design methods such as those related to the running safety suffer from a vague scientific background questioning their reliability or optimality. Therefore, the current article is devoted to updating the conventional design methodology, using Reliability-Based Design Optimization (RBDO) to propose the minimum allowable mass and stiffness which assures satisfying the target reliability. These proposed minimum design values can conceptually replace the conventional partial safety factor-based design method for running safety without the need for dynamic analysis. If the mass and stiffness resulting from the control of other limit states meet the proposed minimum values, the desired target reliability for running safety will be assured. This is achieved by adaptively training Kriging meta-models as a surrogate for the computational models decoupling the RBDO problem. In this regard, a new stopping criteria is proposed using mis-classification ratio of the cross-validated model; which reduces the generalization error of the trained meta-model and consequently the estimated failure probability. Moreover, due to the dependence of the design variables, the Copula concept is used to refine the augmented space and reformulate the RBDO problem., QC 20230710

This work presents the results from an experimental test on a 97 m long lightweight footbridge in Stockholm, Sweden. The modal properties were estimated based on impact hammer testing. The experimental results show that the lightweight steel footbridge presents damping ratios in accordance with the Sétra Technical Guide for footbridges. Furthermore, the work presents a 3D Finite Element (FE) model of the footbridge. The bridge model is first tested by performing a sensitivity analysis of the boundary conditions with respect to the modal properties of the system. Next, the model is adjusted using a frequency-based modal updating technique with a Genetic Algorithm (GA) to solve the optimization problem. Finally, the model results are compared with the experimental test, and the vicinity of the obtained solution is evaluated. The FE model shows a good agreement with respect to the experimental results in terms of bending natural frequencies and corresponding mode shapes., Part of ISBN 9781003348443QC 20230802

Structural damping is an important characteristic in railway bridges, which affects the performance of the structure, especially for bridges with train speeds higher than 200 km/h. The accurate evaluation of damping must be performed properly to correctly assess the structural performance of the bridge under dynamic loading conditions. The present article introduces an alternative methodology that contributes to the assessment of damping coefficients with application to railway bridges. The methodology is based in the Prony method with an energy-sorting technique for the identification of dominant frequencies of a free vibration signal of a passing train. The numerical validation of the method is based on a sensitivity analysis of the free vibration periods of signals through the evaluation of influence lines of displacement and numerically simulated receptance tests, and in the estimation of the damping coefficient from the free vibration period obtained in a train-bridge interaction dynamic analysis with a known imposed value. Finally, and in the scope of the In2Track2 and In2Track3 projects, the experimental assessment of damping coefficients using this methodology was carried out, considering four filler-beam bridges from the Portuguese Railway Network. The ambient vibration tests allowed the evaluation of the main frequencies and damping in these bridges, and the dynamic tests under railway traffic allowed the definition of the dynamic response of these bridges and subsequent application of the Prony method for two types of trains. The results of this work allow a new update of the database for damping coefficients of filler-beam railway bridges, contributing to future revisions of EN1991-2., QC 20230403

Detta examensarbete har undersökt hur låg- respektive högpresterande elever påverkas av problemlösningsuppgifter i matematikundervisningen. Är det främst de relativt högpresterande eleverna som har störst nytta av matematisk problemlösning för att få en djupare förståelse i matematik? Kan problemlösning användas för att få upp intresset för lågpresterande elever? Spelar det någon roll hur problemuppgifter är formulerade? Arbetet har genomförts genom en begränsad systematisk litteraturöversikt genom en databassökning via sökmotorerna DiVA, ERIC och Springer följt av en narrativ analys av tolv utvalda artiklar. Resultatet från detta examensarbete tyder på det främst är de relativt högpresterande eleverna som har störst nytta av matematisk problemlösning för att få en djupare förståelse i matematik. Det är främst dessa elever som möter problemlösning i sin matematikundervisning, vilket gör att de blir mer vana vid problemlösning än andra elever. De lågpresterande eleverna ges inte samma möjligheter att utveckla sin förmåga att lösa matematiska problem. Problemlösning kan dock användas för att få upp intresset för lågpresterande elever. Gruppsammansättningar kan här ha en stor betydelse för hur bra elever kan prestera. Lågpresterande elever presterar t.ex. bättre efter samverkan i en heterogen grupp tillsammans med mer högpresterande eleverna. Resultatet tyder också på att det har betydelse hur problemuppgifter är formulerade för att öka elevernas förutsättning att utveckla sina förmågor att lösa matematiska problem. Textbaserade problemlösningsuppgifter anpassas sällan till elevernas kunskapsnivå. Problemlösningsuppgifter bör därför vara konstruerade så att de inte är för svåra utan är anpassade till elevens kunskapsnivå. Det finns t.ex. en tydlig koppling mellan textbaserad problemlösning och elevernas läsförståelse. Examensarbetet drar också slutsatsen att elever får begränsade förutsättningar att skapa lösningsmetoder eftersom uppgifterna i deras läroböcker mycket s, This thesis has investigated how low- and high-achieving students are affected by problem-solving tasks in mathematics education. Is it primarily the relatively high-achieving students who benefit most from mathematical problem solving to gain a deeper understanding in mathematics? Can problem solving be used to raise the interest of low-achieving students? Does it matter how problem solving tasks are formulated? The work has been carried out through a rapid systematic literature review through a database search via the search engines DiVA, ERIC and Springer, followed by a narrative analysis of twelve selected articles. The results from this thesis indicate that it is primarily the relatively high-achieving students who benefit most from mathematical problem solving to gain a deeper understanding in mathematics. It is mainly these students who encounter problem solving in their mathematics teaching, which means that they become more accustomed to problem solving than other students. The low-achieving students are not given the same opportunities to develop their ability to solve mathematical problems. However, problem solving can be used to raise the interest of low-achieving students. Here, group compositions can have a major impact on how well students can perform. Low-achieving students perform e.g. better after collaboration in a heterogeneous group together with higher performing students. The results also indicate that it is important how problem tasks are formulated to increase the students' prerequisites for developing their abilities to solve mathematical problems. Text-based problem-solving tasks are rarely adapted to the students' level of knowledge. Problem solving tasks should therefore be constructed so that they are not too difficult but are adapted to the student's level of knowledge. There is e.g. a clear connection between text-based problem solving and students' reading comprehension. The thesis also concludes that students are given limited oppor

Sammanfattning Titel: Effektiva marknadshypotesen EMH, Momentum - Investeringsstrategi Nivå: Examensarbete på grundnivå (kandidatexamen) i ämnet företagsekonomi Författare: Andreas Andersson och Alexander Andersson Handledare: Peter Lindberg Datum: 2023 - Juni Syfte: Syftet med denna studie är att testa den effektiva marknadshypotesen genom investeringsstrategin momentum. Metod: Studien har en deduktiv ansats där en kvantitativ metod har använts för att samla in sekundärdata från olika databaser. Olika marknader har analyserats genom att skapa olika momentumportföljer som bygger på momentum som är en investeringsstrategi för att testa hur effektiva dessa marknader är. Resultat & Slutsats: Studiens resultat visar att olika marknader är olika effektiva. Momentumstrategi 1 gav inte en överavkastning och momentumstrategi 2 gav en överavkastning på samtliga portföljer. Uppsatsens bidrag: Studien bidrar med kunskap om olika marknaders effektivitet. Den ger även kunskap om hur momentum fungerar som investeringsstrategi på olika marknader och tillgångar. Förslag till fortsatt forskning: Förslag på vidare forskning är att undersöka andra marknader och använda momentum som investeringsstrategi på andra tillgångar samt att använda sig av kortare momentumsignaler. Nyckelord: Effektiva marknadshypotesen, Anomalier, Investeringsstrategi, Momentum, Momentumstrategi, Momentumportfölj, Jämförelseindex, Buy and Hold Strategi.

Coastal upwelling regions are among the most productive marine ecosystems but may be threatened by amplified ocean acidification. Increased acidification is hypothesized to reduce iron bioavailability for phytoplankton thereby expanding iron limitation and impacting primary production. Here we show from community to molecular levels that phytoplankton in an upwelling region respond to short-term acidification exposure with iron uptake pathways and strategies that reduce cellular iron demand. A combined physiological and multi-omics approach was applied to trace metal clean incubations that introduced 1200 ppm CO2 for up to four days. Although variable, molecular-level responses indicate a prioritization of iron uptake pathways that are less hindered by acidification and reductions in iron utilization. Growth, nutrient uptake, and community compositions remained largely unaffected suggesting that these mechanisms may confer short-term resistance to acidification; however, we speculate that cellular iron demand is only temporarily satisfied, and longer-term acidification exposure without increased iron inputs may result in increased iron stress.