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This thesis focuses mainly on nonlinear dimensionality reduction. A comparison of a number of different extensions of the Isomap-algorithm found in the literature is presented as well as an introduction to the underlying theory. Further, two novel extensions of the algorithm are introduced. Residual variance is used as a means of quantifying performance and optimizing parameters. One of the novel approaches, NNL-Isomap, is applied to financial data sets such as the S&P 500, the results are compared with those from PCA and, when appropriate, well-known academic models. The thesis further introduces a selection of concepts from topological data analysis together with corresponding short explanatory examples as well as applies these concepts to some simple financial examples. Denna uppsats huvudfokus kretsar kring ickelinjär dimensionsreducering. En jämförelse av ett antal olika kända utvidgningar av Isomap-algoritmen ges, samt en introduktion till den bakomliggande teorin. Vidare presenteras två egenutvecklade utvidgningar av algoritmen. För att mäta prestanda samt optimera parametrar används residual variance-metoden. En av de egenutvecklade utvidgningarna, NNL-Isomap, appliceras på finansiella dataset såsom från S&P 500, och dess resultat jämförs med både det av PCA samt välkända akademiska modeller. Ett urval av begrepp härstammandes från topologisk dataanalys introduceras tillsammans med ett par korta exempel, dessa begrepp appliceras sedan på enklare finansiella exempel.

This report is about a novel approach to attenuation of fan noise in aerial vehicles, by way of implementing a ducted fan in the chassis of a four meter blended wing body plane. Three different one meter PVC pipes were used and their performances as silencers were tested by measuring the sound power level and calculating the insulation loss compared to a fan by itself. The ducts were either empty or lined with acoustic absorbents and micro perforated panels. Experiments were carried out in the reverberation room at KTH Marcus Wallenberg laboratory for sound and vibration research using the guidelines in ISO 3741 (2010). The results showed that the empty duct lead to a 15.3 dB(A) insulation loss with no decrease in thrust from the fan. The absorbent and micro perforated panel, however, lead to a 22.7 dB(A) insulation loss while giving a major decrease in thrust of more than one order of magnitude. The results show the failure of implementation of the latter two silencers due to choking, but also the success of the empty duct. This shows that there is room for improvement and perhaps even a future possibility of a successful implementation in a real vehicle.

The process of gentrification may be seen as black and white, as at least some of the academic discourse is centered around how gentrifiers are displacing locals. This paper reveals some insight into how the process of gentrification may be more complex. Gentrification is perceived to have an array of outcomes beyond the displacement of locals. This paper uses a qualitative method, using subjective experiences of gentrification, to renew the discussion on the topic. This was done by performing interviews with locals who live in London. Four interviews were conducted, which was limited yet did provide some perception insight. Two specific boroughs were also chosen, Tower Hamlets and Hammersmith and Fulham. The perception also derives from those who work in the creative industry, which consists of theaters, museums, games, and boutiques. This paper examines how this specific industry feels, positively or more negatively, about changes in their urban environment or to their creative business and how they overall perceive gentrification. The aim of this paper and the interview questions is to find out what is the creative industries' perspective on the gentrification process in London. This research was limited by the amount of interviews that were conducted as only four were performed. Although by analyzing the interviews in this paper, it can be seen that there are mixed responses about how the creative industry perceives gentrification.

This thesis report revolved around the cloning process of plasmids. Attempts of cloning the red fluorescent protein mCherry, and the green fluorescent protein EGFP from various plasmids, into other plasmids containing different cell-junction/cytoskeleton plasmids were made. These plasmids were first amplified using PCR, and then cloned using Gibson-Assembly, and then transfected into live HEK293T or MDCK-II cells. After the transfection, the cells were examined in a microscope. The results showed no signal or localization for the cloned plasmids in their respective corresponding channel, 561 nm for the red fluorescent protein mCherry or 488 nm for the green fluorescent protein EGFP. The step that went wrong was the PCR step in the cloning process, since the backbone vector was not successfully amplified. The reasons for this was either that the backbone vector was too long, the primers regions were to rich with Guanine and Cytoseine, or the primers being too long. Den här tesen kretsade kring kloningsprocessen för plasmider. Det gjordes försök att från plasmider klona in det röda fluorescerande proteinet mCherry, samt det gröna fluorescerande proteinet EGFP in i andra plasmider som innehöll olika cell-junction proteiner. Både det fluorescerande fragmenten och plasmid-vektorerna innehållande cell-junction proteinerna amplifierades med PCR. Sedan gjordes Gibson-Assembly som var själva kloningsmetoden. Efter det transfekterades HEK293T, samt MDCK-II celler med lösningen från Gibson-Assembly kloningen. Dessa celler undersöktes sedan i mikroskop. Resultatet visade inga tydliga signaler varken i 561 nm kanalen (mCherry), eller i 488 nm kanalen (EGFP), vilket betyder att kloningen inte fungerade. Steget som gick fel var PCR-steget i själva kloningsprocessen, då plasmid-vektorerna inte amplifierades. Anledningen till detta var antingen att själva plasmid-vektorerna var för långa, primer regionerna hade för mycket Guanin och Cytosin, eller att alla primers själva var för långa.

With a rapid transition towards renewable energy sources and increasing demand for electricity, we are facing major changes in the electricity grid. With increased congestion and reduction of inertia the grid is becoming more sensitive to rotor angle stability issues, such as the stability of interarea modes or power oscillation damping (POD). This thesis shows that the use of local measurements for POD improvement could lead to reduced transient rotor angle stability. Depending on fault location it is shown that reduction of the first swing is not always feasible, and depending on the controller the first swing could be amplified and in the worst case lead to a power blackout due to the tripping of generators and transmission lines. The reason for the behavior is, among other things, rooted in the fundamental limitations of using local measurements, where the estimate of the inter-area mode detects the wrong signs of the disturbance. Nonlinear simulations are performed in the nordic32 bus Simulink model in order to validate the results. Med en snabb övergång till förnybara energikällor och ökad efterfrågan på el står vi inför stora förändringar i elnätet. Med ökad belastning och minskad rörelsemängd blir nätet mer känsligt för problem relaterade till rotorvinkelstabilitet, så som stabiliteten av interareapendlingar eller kraftoscillationsdämpning (POD). Denna avhandling visar att användningen av lokal mätning för POD-förbättring kan leda till minskad transient rotorvinkelstabilitet. Beroende på var felet inträffar visas det att dämpning av den första svängningen inte alltid är möjlig, och beroende på regulatorndesign kan den första svängningen förstärkas och i värsta fall leda till en strömavbrott på grund av brotkopplade generatorer eller transmissionsledningar. Detta fenomen är bland annat sprunget ur de fundamentala begränsningarna i användnignen av lokal mätning, där estimeringen av interareapendlingen initialt estimerar fel tecken på störningen. Icke- linjära simuleringar utförs i nordic32 Simulink-modellen för att validera resultaten.

I takt med att tekniken utvecklas gör även underhållsstrategierna det. Trots detta är det många företag som fortfarande använder samma underhållsstrategier som man alltid gjort. Olika underhållsstrategier ser behovet av underhåll på olika sätt, allt från att vänta tills felet uppstår till att förebygga fel genom avancerad dataanalys och det kan därför vara svårt för underhållsorganisationer att välja rätt strategi. Detta arbete undersöker hur ett byte av underhållsstrategi kan påverka effektiviteten av underhållet i en större organisation, med fokus på kostnader, personalresurser och tillgänglighet på utrustning. PostNord har valts som fallstudie. De strategier som jämförs och utvärderas är; avhjälpande underhåll, förebyggande underhåll, tillståndsbaserat underhåll samt prediktivt underhåll. Resultatet påvisar ökad effektivitet för tre av fyra strategier, som också ser till företagets behov. Den efterföljande diskussionen av resultatet visar att det framtida behovet är oklart där främst två faktorer som påverkar; årliga volymminskningar samt morgondagens utdelningsmodell. Slutsatsen blir att det finns två olika rekommendationer beroende på hur det framtida behovet ter sig. Om det är ett fortsatt behov av hög tillgänglighet på maskinerna så rekommenderas en kombination av prediktivt underhåll och förebyggande underhåll på drifttid. Om det framtida behovet däremot påvisar att tillgängligheten inte kommer att påverka beslutet i samma grad rekommenderas en kombination av förebyggande underhåll på drifttid och tillståndsbaserat underhåll där tillståndsmätningar görs mot den data som samlas in idag. I båda rekommendationerna räknas fortfarande avhjälpande underhåll in som strategi för hantering av de akuta stopp som kan uppstå. Att titta på andra maskintyper där det framtida behovet framgår tydligare föreslås som fortsatt arbete. As technology evolves, so do maintenance strategies. Despite this, many companies tend not to change maintenance strategy. Maintenance strategies differ significantly in the way they address the need for maintenance, for some the strategy is to provide maintenance after a fault has occurred while others focus on preventing faults through advanced data analysis. With this diversity in approach, it may be difficult for maintenance organizations to choose the right strategy. This thesis examines how a change of maintenance strategy can affect the efficiency of maintenance in a larger organization, focusing on costs, personal resources and availability of the equipment. As a case study, PostNord has been the selected company for the study. The study compares and evaluates four maintenance strategies; corrective maintenance; preventive maintenance; condition-based maintenance; and predictive maintenance. The results show increased efficiency for three out of four strategies, which also meet the needs of the company. In the discussing the results in the context of PostNord, annual volume reductions and future distribution model, are identified as the two main factors that will affect the future validity and application of results. Subsequently, the conclusion consists of two recommendations depending on distribution model and annual volumes. If there is a continued need for high availability in the machines, then the combination of predictive maintenance and preventative maintenance on operating time is recommended. If the future need does impact on the need of availability, then a combination of preventive maintenance on operating time and condition-based maintenance where measurements are made against the data that are accessible today is recommended. Both recommendations still include corrective maintenance as a strategy for managing the emergency stops that may occur. To focus on machines with a clearer future need are recommended for continued work.

Social robots have a recognizable physical appearance, a distinct voice, and interact with users in specific contexts. Previous research has suggested a ‘matching hypothesis’, which seeks to rationalise how people judge a robot’s appropriateness for a task by its appearance. Other research has extended this to cover combinations of robot voices and appearances. In this paper, we examine the missing connection between robot voice, robot appearance, and deployment context. In so doing, we asked participants to match a robot image to a voice within a defined interaction context. We selected widely available social robots, identified task contexts they are used in, and manipulated the voices in terms of gender, naturalness, and accent. We found that the task context mediates the ‘matching hypothesis’. People consistently selected a robot based on a vocal feature for a certain context, and a different robot based on the same vocal feature for another context. We suggest that robot voice design should take advantage of current technology that enables the creation and tuning of custom voices. They are a flexible tool to increase perception of appropriateness, which has a positive influence on Human-Robot Interaction.

Introduction: Concussions in American Football are of a major concern due to highly reported injury rates. The importance of properly designed helmets have shown effect in reducing the risk of injuries, such as skull fractures. However, they are not as effective in reducing the risk of concussion. Helmets designed are required to pass standards and regulations for them to be allowed within the football leagues. The current test methods evaluate linear impacts, but lack evaluations of oblique impacts which are believed to cause concussions. Several test methods have been suggested, but little is known regarding how they compare. Objective: The purpose of this study was to compare three different test methods for evaluating helmet performance, utilizing finite element simulation. Three different helmet models were used for comparison, evaluating head kinematics. The helmet models were additionally ranked from best to worst based on their performances. Method: Three test methods, linear impactor, 45° angled linear impactor, and a drop test onto a 45° angled plate were simulated with three different open source helmet models. Simulations were conducted with one impact velocity at three impact locations. The influence of the interaction between helmet and head was also evaluated by altering the friction coefficient. Results: The test methods showed different results depending on helmet models, impact locations, and kinematics evaluated. Similarly, rankings of the helmets were varied based on methods and impact location. Little difference was observed after lowering the friction coefficient in majority of cases. The linear and angular acceleration for the drop side impact were mostly affected. Conclusion: Further evaluations of the test methods and comparison to real impacts is required to evaluate what method resembles head impacts best. Lowered friction coefficient had an effect for the drop impacts, but minor effect for other test methods

The Examination Timetabling Problem (ETP) is the problem of scheduling a number of exams during a set time period so that no students are required to sit two exams simultaneously. Despite the complexity of the problem, universities all over the world solve ETPs several times each year. Two known methods for solving ETPs is using either heuristics or Hopfield Neural Networks (HNN). This thesis compares the performance of a heuristic algorithm implemented with Local Search, Simulated Annealing and Tabu Search to the performance of a HNN algorithm. Both algorithms were executed on ten different ETPs reduced to Graph Colouring Problems (GCP). The results show that the heuristic algorithm always generated more satisfactory solutions to the ETPs than the HNN. The HNN was, however, implemented as software in this thesis. It is intended to be implemented as hardware and if this method were to have been used instead the HNN algorithm might have produced other results. At this stage the heuristic algorithm is more suitable than the HNN algorithm for solving ETPs. Schemaläggningsproblem för examinationer (ETP) syftar på problemet att schemalägga ett antal examinationer under ett bestämt tidsintervall så att ingen student behöver närvara på flera examinationer samtidigt. Det är ett komplext problem som universitet världen över behöver lösa flera gånger per år. Två kända metoder för att lösa ETPs är användning av antingen heuristiker eller Hopfield Neural Networks (HNN). Den här uppsatsen jämför prestandan av en heuristik implementerad med Lokal Sökning, Simulerad Härdning och Tabusökning med presentandan av en HNN-algoritm då båda metoderna exekveras på tio ETPs reducerade till Graffärgningsproblem (GCP). Resultaten visar att heuristiken alltid genererade mer tillfredsställande lösningar till schemaläggningsproblemen än HNN-algoritmen gjorde. HNN-algoritmen, som egentligen bör implementeras som hårdvara, implementerades dock som mjukvara i den här avhandlingen. Hade den implementerats som hårdvara istället hade kanske andra resultat producerats. För tillfället lämpar sig heuristiken bättre än HNN-algoritmen för att lösa ETPs.

Infrastructure investment and management often incur high capital cost that dictates the decision making during the planning phase. Future operation and maintenance costs have been considered but in different methods. With the pressure of existing aging infrastructure, the need to cut down maintenance cost has been highlighted. Currently, there is a lack of a standardized framework for decision making. Delay in decision making will lead to construction delay and increase in construction cost. This MSc thesis discusses the various frameworks available and proposes the optimal framework. Life Cycle Cost Analysis (LCCA) provides a methodology to evaluate an object, e.g. a road, through including investment, operation, maintenance, dismantling and landfill or recycling. Higher cost saving will be possible to achieve if LCCA can be applied during the planning phase of the construction. Thus, LCCA is studied and applied on a case study of a section along a 9- km road in south of Sweden. By considering the specific site conditions such as soil profile and road alignment, this thesis evaluates its effect on LCCA. Sensitivity analysis is carried out on the cost output due to uncertainty variable input of the data. The aim of this thesis is to formulate a generic model/tool for decision making based on LCCA methodology on the project level. The rules and regulations provided by Trafikverket (Swedish Transport Administration) and ISO standard for life cycle costing are used as parameters during the analysis. The model described above can be used in different countries if these parameters are redefined by adapting local standards and conditions. This thesis demonstrates the application of the model with a case study to discuss the difference between two different alternatives. The case study compares two alternatives for the same stretch of the road. The first alternative proposes a longer bridge while the second alternative provides a shorter bridge. The result shows that the first alternative has slightly lower LCC compared to the second alternative. Through understanding all the costs connected to the project, cost calculation has been adjusted to ensure accuracy of the data input. Finally, the result from the cost comparison is tested with Monte Carlo Simulation to manage uncertainty risks.