We study the question of periodic homogenization of a variably scaled reaction-diffusion equation with non-linear drift of polynomial type. The non-linear drift was derived as hydrodynamic limit of a totally asymmetric simple exclusion process (TASEP) for a population of interacting particles crossing a domain with obstacle. We consider three different geometries: (i) Bounded domain crossed by a finitely thin flat composite layer; (ii) Bounded domain crossed by an infinitely thin flat composite layer; (iii) Unbounded composite domain.\end{itemize} For the thin layer cases, we consider our reaction-diffusion problem endowed with slow or moderate drift. Using energy-type estimates as well as concepts like thin-layer convergence and two-scale convergence, we derive homogenized evolution equations and the corresponding effective model parameters. Special attention is paid to the derivation of the effective transmission conditions across the separating limit interfaces. As a special scaling, the problem with large drift is treated separately for an unbounded composite domain. Because of the imposed large drift, this nonlinearity is expected to explode in the limit of a vanishing scaling parameter. To deal with this special case, we employ two-scale formal homogenization asymptotics with drift to derive the corresponding upscaled model equations as well as the structure of the effective transport tensors. Finally, we use Schauder's fixed point Theorem as well as monotonicity arguments to study the weak solvability of the upscaled model posed in the unbounded domain. This study wants to contribute with theoretical understanding needed when designing thin composite materials which are resistant to slow, moderate, and high velocity impacts. / We study the question of periodic homogenization of a variably scaled reaction-diffusion equation with non-linear drift of polynomial type. The non-linear drift was derived as hydrodynamic limit of a totally asymmetric simple exclusion process (TASEP) for a population of interacting particles crossing a domain with obstacle. We consider three different geometries: (i) Bounded domain crossed by a finitely thin composite layer; (ii) Bounded domain crossed by an infinitely thin composite  layer; (iii) Unbounded composite domain. For the thin layer cases, we consider our reaction-diffusion problem endowed with slow or moderate drift. Using energy-type  estimates, concepts like thin-layer convergence and two-scale convergence, we derive  homogenized  equations. Special attention is paid to the derivation of the effective transmission conditions across the separating limit interfaces. The problem with large drift is treated separately for an unbounded composite domain. Because of the imposed large drift, this nonlinearity is expected to explode in the limit of a vanishing scaling parameter.  This study wants to contribute with theoretical understanding needed when designing thin composite materials which are resistant to slow, moderate, and high velocity impacts.

This thesis investigates the strengths and weaknesses of omnidirectional drive and differential drive systems on mobile manipulator robots. Based on a literature study, a hypothetical use case, and identified Key Performace Indicators the drive system’s effects on the performance of the mobile manipulator are evaluated. A qualitative approach was used for evaluation. The research methodology involved analyzing the wheel characteristics of each drive system, identifying parameters affecting the performance, and assessing the two drive system characteristics within the context of the hypothetical use case. Six Key Performance Indicators such as pose accuracy, space utilization, and manipulability were formulated and examined to determine the comparative strengths and weaknesses of the drive systems. The results confirmed that omnidirectional drive systems exhibit greater maneuverability and agility while differential drive systems are less complex and often more durable in rough conditions. However, the results also show that in many cases the answer on what drive system to use will depend on many factors and that these factors can affect the overall performance of the mobile manipulator. This study provides insights into performance-affecting parameters and relevant performance aspects by examining the strengths and weaknesses of omnidirectional and differential drive systems. While acknowledging the need for caution in generalizing the findings and assuming validity in real-world applications, the results obtained serve as a starting point for further investigations. / Detta examensarbete undersöker styrkor och svagheter hos omnidirektionella drivsystem och differentialdrivsystem på mobila manipulatorer. En kvalitativ metod, baserat på en litteraturstudie, ett hypotetiskt användningsscenario och identifierade prestationsindikatorer, användes för att utvärdera drivsystemets effekter på den mobila manipulatorns prestanda. Forskningsmetodiken innebar att analysera hjulegenskaperna för varje drivsystem, identifiera parametrar som påverkar prestandan och bedöma de två drivsystemens egenskaper inom ramen för det hypotetiska användningsfallet. Viktiga prestationsindikatorer som poserings noggrannhet, utrymmesutnyttjande och manipulerbarhet undersöktes för att fastställa och jämförande styrkorna och svagheterna hos drivsystemen. Resultaten bekräftade att omnidirektionella drivsystem uppvisar större manövrerbarhet och smidighet medan differentialdrivsystem ofta är mindre komplexa och mer hållbara under tuffa förhållanden. Dock visar resultaten även att svaret på vilket drivsystem som ska användas i många fall beror på flertalet faktorer och att dessa faktorer kan påverka den mobila manipulatorns totala prestanda. Denna studie ger insikter i prestandapåverkande parametrar och relevanta prestandaaspekter genom att undersöka styrkorna och svagheterna hos omnidirektionella och differentiella drivsystem. Samtidigt som man erkänner behovet av försiktighet med att generalisera resultaten och anta giltighet i verkliga tillämpningar, tjänar de erhållna resultaten som en utgångspunkt för ytterligare undersökningar.

Among the research topics needing to be addressed to further the development of phased array feeds (PAFs) for radio astronomical use are challenges associated with calibration, beamforming, and imaging for single dish observations. This dissertation addresses these concerns by providing analysis and solutions that provide a clearer understanding of the effort required to implement PAFs for complex scientific research. It is shown that calibration data are relatively stable over a period of five days and may still be adequate after 70 days. A calibration update system is presented with the potential to refresh old calibrators. Direction-dependent variations have a much greater affect on calibration stability than temporal variations. There is an inherent trade-off in beamformer design between achieving high sensitivity and maintaining beam pattern stability. A hybrid beamformer design is introduced which uses a numerical optimizer to balance the trade-off between these two conflicting goals to provide the greatest sensitivity for a desired amount of pattern control. Relative beam variations that occur when electronically steering beams in the field of view must be reduced in order for a PAF to be useful for source detection and imaging. A dual constraint beamformer is presented that has the ability to simultaneously achieve a uniform main beam gain and specified noise response across all beams. This alone does not reduce the beam variations but it eliminates one aspect of the problem. Incorporating spillover noise control through the use of rim calibrators is shown to reduce the variations between beams. Combining the dual constraint and rim constraint beamformers offers a beamforming option that provides both of these benefits.

<p>  </p> <p>Evolution is the foundation for all of biology. However, our approaches and understanding of evolution—simply, the change of allele frequencies from one generation to the next—have themselves evolved over time. In this dissertation I explore multiple approaches to understand evolution and the consequences of evolution across variable scales and study organisms. First, I use meta-analytic techniques and Bayesian hierarchical models to investigate the phenotypic consequences of two forms of cryptic local adaptation, co- and countergradient variation, by leveraging a decades-old quantitative genetics approach (Chapter 1). I find large effects for both co- and countergradient variation, however they are obscured in natural settings by concurrent large environmental effects. I also show that these large effects are ubiquitous across phenotypic traits, organisms, and environmental gradients, suggesting that while similar phenotypes may be the evolutionary end point, the mechanisms to achieve those phenotypes likely vary. In the following chapter I explore the rapid evolution of a unique and understudied species introduction, pink salmon (<em>Oncorhynchus gorbuscha</em>) in the Great Lakes. Pink salmon were introduced into Lake Superior in a single introduction event and have broken two obligate life histories, anadromy (though they treat the Great Lakes like surrogate oceans) and their fixed two-year life cycle, making them ripe subjects for contemporary evolution. Using whole-genome sequence data, I first investigate the effects of a genetic drift in the form of a bottleneck at introduction and characterize the subsequent loss of genetic diversity (Chapter 2). I show that despite a large loss of genetic diversity, pink salmon also rapidly adapted to their novel environment based on signals of putative selection across numerous regions of the genome, particularly in a period gene associated with their daily circadian clock (<em>per2</em>). Next, I explore how genome structure likely aided adaptation by pink salmon to the Great Lakes, providing evidence that a supergene (~29 Mbp) containing an inversion on chromosome 10 swept to near fixation in the Great Lakes (Chapter 3) and likely aided in osmoregulatory adaptation to this novel environment. Finally, I end with a short perspective chapter (Chapter 4) where I highlight potential future research directions for each of the previous chapters. Together, this research investigates the drivers and consequences of evolution across multiple scales and shows the powerful effect of genetic drift and genetic adaptation in shaping the genomic and phenotypic attributes of populations.</p>

The railway infrastructure needs to be safe, reliable and efficient in order to meet the growing demand of sustainable transportation methods. One of the main problems the railway industry faces today is that a higher traffic load increases the need for maintenance, at the same time as it reduces the availability of gaps in the timetables to perform maintenance activities. Unmanned Aerial Vehicles, UAVs, have in recent years been adopted commercially due to their potential of increasing work efficiency and productivity. Different actors in the railway industry have recently started to explore and test the possibilities of implementing UAVs. The objective of this master thesis was to investigate and define use case scenarios where the use of UAVs would create value for railway infrastructure operations and maintenance activities. It is meant for both stakeholders in the railway industry to gain better understanding of capabilities and limitations of UAV technology but also provide recommendations to UAV manufacturers to understand the railway industry and potential UAV applications. Theoretical research and qualitative user studies with UAV professionals and relevant stakeholders within the railway industry were conducted in order to gain insight in the railway industry and to identify potential use case scenarios. The research showed that maintenance activities to a large extent are performed either manually by walking along the tracks which is inefficient, physically demanding and dangerous or by using test/measurement vehicles which require track occupancy. It was concluded that the use of UAVs would mainly create value by; enabling remote inspection and operation, accessing the infrastructure without track occupancy or the need of roads. At the same time, improve the working conditions, efficiency and quality of maintenance activities. The thesis resulted in 15 potential use case scenarios for UAVs in the railway industry and proposals for common UAV solutions based on functional requirements. / Järnvägssystemet måste vara säkert, pålitligt och effektivt för att möta den växande efterfrågan på hållbara transportmetoder. Ett av de största problemen som den svenska järnvägsindustrin står inför idag är att ökad trafikbelastning ökar behovet av underhåll, samtidigt som det minskar tillgängligheten för att utföra underhållsaktiviteter. Obemannade flygfordon, även kallade drönare, har under de senaste åren tillämpats mer frekvent i kommersiella syften för att bland annat uppnå ökad effektivitet och produktivitet. Aktörer inom järnvägsindustrin har nyligen börjat utforska och testa möjligheterna att använda drönare. Syftet med detta examensarbete var att undersöka och definiera potentiella tillämpningar av drönare med syfte att skapa värde för drift- och underhållsarbete inom järnvägen. Denna rapport är avsedd för intressenter inom järnvägsindustrin att få bättre förståelse för kapaciteten och begränsningar av drönarteknik samt ge rekommendationer till drönartillverkare för att bättre förstå järnvägsindustrin och potentiella användningsområden. Teoretisk undersökning och kvalitativa användarstudier med drönarexperter och relevanta intressenter inom järnvägsindustrin genomfördes för att få insikt i järnvägsindustrin samt för att identifiera problemområden. Studien visade att underhållsverksamheten i stor utsträckning utförs antingen manuellt genom att gå längs spåren vilket är ineffektivt, fysiskt krävande och farligt eller genom att använda test/mätfordon som kräver tillgång till spår. Arbetet resulterade i 15 potentiella tillämpningar av drönare i järnvägsindustrin samt förslag på gemensamma drönarlösningar baserade på funktionella krav. Slutsatsen drogs att tillämpningen av drönare i järnvägsindustrin främst kan skapa värde genom att; på distans utföra underhållsaktiviteter och inspektioner, få tillgång till infrastrukturen utan behov av spår eller vägar. Detta resulterar i förbättrade arbetsförhållanden samt ökad effektivitet och kvalitet på underhållsarbetet.

This master thesis investigates and analyzes the energy use for traction and auxiliary equipment in passenger rail vehicles. It covers both the train service with passengers and when the trains are going through other stages in the everyday operation. The operational cycle and associated operational situations are introduced as a way of describing the varying use of a train over time. The descriptions focus on the most common activities and situations, such as stabling and parking, regular cleaning, inspections and maintenance. Also how these situations affect energy use by their need for different auxiliary systems to be active. An energy model is developed based on the operational cycle as a primary input, together with relevant vehicle parameters and climate conditions. The latter proving to be a major influence on the energy used by the auxiliary equipment. The model is applied in two case studies, on SJ's X55 and Västtrafik's X61 trains. Both are modern electric multiple units equipped with energy meters. Model input is gathered from available technical documentation, previous studies and by measurements and parameter estimations. Operational cycle input is collected through different planning systems and rolling stock rosters. Climate input is finally compiled from open meteorological data banks. The results of the case studies show that the method and models are useful for studying the energy used by the trains in their operational cycles. With the possibility to distinguish the energy used by the auxiliary equipment, both during and outside the time the trains are in service with passengers. With this it's also possible to further investigate and study potential energy saving measures for the auxiliary equipment. Simulations of new ventilation control functions and improved use of existing operating modes on the trains show that considerable energy savings could be achieved with potentially very small investments or changes to the trains. The results generally show the importance of a continued investigation of the auxiliary equipment's energy use, as well as how the different operational situations other than the train service affect the total energy use. / Detta examensarbete utreder och analyserar energianvändningen för passagerarjärnvägsfordons traktion- och hjälpkraftssystem, både under tågdriften med passagerare och andra delmoment som tågen genomgår under den normala dagliga driften. För detta introduceras driftcykeln och tillhörande driftsituationer som ett sätt att beskriva användningen av ett tåg över tiden. Syftet är att beskriva de vanligast förekommande aktiviteterna och situationerna, såsom uppställning och parkering, regelbundna inspektioner, klargörningar och underhåll. Även hur dessa situationer påverkar energianvändningen genom ett varierande behov av hjälpkraft och aktiva funktioner i tågen. En energimodell baserad på driftcykeln som huvudsaklig indata, tillsammans med tågets egenskaper samt det omgivande klimatet, tas fram. Klimatet visar sig vara en avgörande faktor i hjälpkraftens energianvändning. Modellen utvärderas i typstudier på SJs X55 och Västtrafiks X61. Båda är elektriska motorvagnståg utrustade med energimätare. Indata till modellen samlas in genom tillgänglig teknisk dokumentation, tidigare studier och genom mätningar samt parameterestimering. Driftcyklerna för tågtyperna sammanställs med hjälp av olika planeringssystem och omloppsplaner. Väder- och klimatdata samlas slutligen in från öppna databaser för metrologiska data. Resultaten från typstudierna visar att metoden och modellerna är användbara verktyg för att kunna beskriva tågens energianvändning i deras driftcykler. Med möjligheten att särskilja hjälpkraftssystemens energianvändning vid tågdriften med passagerare men även i de övriga situationerna. Med detta blir det också möjligt att undersöka potentiella energibesparingsåtgärder för hjälpkraftssystemen. Simulering av förbättrade styrfunktioner för ventilationen och förbättrat utnyttjade av redan inbygga energibesparande driftlägen på tågen visar att betydande energibesparingar kan fås med relativt små medel och få förändringar på fordonen. De sammantagna resultaten av arbetet visar på vikten av att fortsätta undersöka och utreda hjälpkraftens energianvändning samt hur driftsituationerna utanför tågdriften med passagerare påverkar den totala energianvändningen.

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Decarbonizing Sweden’s transport sector is crucial to achieving Sweden’s greenhouse gas reduction goals until 2030 and 2045 as it accounts for one-third of Sweden’s total domestic greenhouse gas emissions. Among the transport sector, maritime vessels are an example that needs to be decarbonized and, as a response, electric solutions have risen as one solution due to the potential benefits, such as greenhouse gas reductions and improved air quality. Thus, investigating how battery-electric propulsion can assist in the transition toward a sustainable maritime sector is of significance. Considering this, the thesis investigates the opportunities and trade-offs between diesel and battery-electric propulsion for a conceptual passenger vessel in the Stockholm archipelago. More specifically, the thesis evaluates technical, environmental, and economic aspects of distinct battery-electric and diesel propulsion alternatives through a life cycle assessment study and life cycle costing analysis. The conducted thesis demonstrates the potential viability of battery-electric propulsion for Stockholm’s public transport. Implementing battery-electric vessels reduces carbon dioxide emissions and pollutants, but results in higher environmental contribution in other areas such as ecotoxicity and land use. Economically, considering the distinct differences between the configurations and without taking into account infrastructure expenses, the battery-electric configurations offer lower long-term costs despite higher initial investments. In addition, the thesis discusses maritime electrification in a broader context, highlighting aspects outside of the study’s scope such as charging infrastructure, social issues related to battery metal extractions, and geopolitical concerns. Therefore, by addressing technical, environmental, economic, as well as other impacts, this thesis provides essential insight from a holistic perspective, guiding policymakers and stakeholders toward a greener future. / Att minska koldioxidutsläppen i Sveriges transportsektor är avgörande för att uppnå Sveriges miljömål med fokus på växthusgaser till 2030 och 2045 eftersom den står för en tredjedel av Sveriges totala inhemska utsläpp av växthusgaser. Inom transportsektorn är fartyg ett exempel som behöver minska sina koldioxidutsläpp och som en respons har batterielektrisk drift kommit upp som en lösning med tanke på de potentiella fördelarna som det kan ge upphov till såsom minskning av växthusgaser och förbättrad luftkvalitet. Med hänsyn till detta undersöker denna avhandling möjligheterna och avvägningarna mellan diesel och batterielektrisk framdrivning för ett konceptuellt passagerarfartyg i Stockholms skärgård. Mer specifikt utvärderar avhandlingen tekniska, miljömässiga och ekonomiska aspekter av distinkta batterielektriska- och dieselframdrivningsalternativ genom en livscykelanalys och livscykelkostnadsanalys. Det genomförda examensarbetet visar den potentiella betydelsen av batteridriven framdrivning för Stockholms maritima kollektivtrafik. Att implementera batterielektriska fartyg minskar exempelvis koldioxidutsläpp och luftföroreningar, men ger upphov till en högre miljömässig påverkan inom andra områden såsom ekotoxicitet och markanvändning. Ur ett ekonomiskt perspektiv och med ett fokus på distinkta skillnader mellan konfigurationerna samt utan att ta hänsyn till kostnader inom infrastruktur erbjuder de batterielektriska konfigurationerna lägre långsiktiga kostnader trots högre initiala investeringar. Dessutom diskuterar avhandlingen marin elektrifiering i ett bredare sammanhang och lyfter fram aspekter utanför studiens avgränsningar såsom laddningsinfrastruktur, sociala frågor relaterat till batterimetallutvinning och geopolitiska problem. Med det sagt, genom att ta upp tekniska, miljömässiga, ekonomiska och andra relevanta effekter ger denna avhandling insikter ur ett holistiskt perspektiv som kan vägleda beslutsfattare och intressenter mot en grönare framtid.

Les études neurophysiologiques de la prise de décision, traditionnellement ancrées dans des principes neuro-économiques, ont évoluées pour inclure une variété d’aires du cerveau. Partant d’abord du lobe frontal associé aux jugements de valeur, le champ s’est élargi pour inclure d’autres types de décisions incluant les décisions perceptuelles et les décisions incarnées qui impliquent notamment les aires sensorimotrices du cerveau. La théorie moderne de la prise de décision modèle l’activité neurale dans ces régions comme une compétition entre les différents stimuli et actions considérés par un individu. Cette compétition est résolue lorsque l’activité neurale associée à un stimulus ou une action choisie atteint un seuil critique. Toutefois, il reste à éclaircir comment ce modèle s’applique aux décisions effectuées alors que l’individu est déjà engagé dans une activité. Dans ce mémoire nous examinons ce type de décision chez des sujets humains dans une tâche de suivi continu. Des cibles « choix » apparaissaient sur un écran pendant que le sujet suivait de la main une cible qui se déplaçait doucement en continu. Le sujet pouvait ignorer ces cibles choix, ou abandonner la cible suivie pour toucher une cible choix, dans quel cas la cible sélectionnée devenait la nouvelle cible à suivre du doigt. Tel qu’attendu, nous avons observé que les sujets favorisaient les cibles plus proches, plus grandes, et les cibles alignées avec l’axe du mouvement. Toutefois nous avons été surpris de constater que les sujets ignoraient les coûts énergétiques du mouvement, tel que modélisés. Un biais pour minimiser les coûts du mouvement fut réintroduis lorsque la tâche fut divisée en séries de mouvements point-à-point, plutôt qu’un mouvement continu. Même si nous ne pouvons expliquer ce résultat surprenant, nous espérons qu’il inspire de futures études utilisant le paradigme expérimental de décision durant l’action. / Neurophysiological studies of decision-making have expanded over decades to involve many brain areas. The field broadened from neuroeconomics, mainly concerned with frontal regions, to perceptual or embodied decision-making involving several sensorimotor areas where neural activity is linked to the stimuli and actions necessary for the decision process. Current models of decision-making envision this neural activity as a competition between different actions that is resolved when enough activity favors one over the other. However, it is unclear how such models can explain decisions often present in natural behavior, where deliberation takes place while already engaged in an action. In this thesis, we examined the choices human subjects made as they were engaged in a continuous tracking task. While they were manually tracking a target on a flat screen, subjects were occasionally presented with a new target to which they could freely choose to switch, whereupon it became the new tracked target. As expected, we found that subjects were more likely to move to closer targets, bigger targets, or targets that were aligned to the direction of movement. However, we were surprised that subjects did not choose targets that minimized energetic cost, as calculated by a biomechanical model of the arm. A biomechanical bias was restored when the continuous movement was broken up into a series of point to point movements. While we cannot yet explain these findings with certainty, we hope they will inspire further studies using decide-while-acting paradigms.