This thesis investigates the use of high-power lasers for synchrotron radiation sources with high brilliance, from the EUV to the hard X-ray spectral range. Hereby lasers accelerate electrons by laser-wakefield acceleration (LWFA), act as optical undulators, or both. Experimental evidence shows for the first time that LWFA electron bunches are shorter than the driving laser and have a length scale comparable to the plasma wavelength. Furthermore, a first proof of principle experiment demonstrates that LWFA electrons can be exploited to generate undulator radiation. Building upon these experimental findings, as well as extensive numerical simulations of Thomson scattering, the theoretical foundations of a novel interaction geometry for laser-matter interaction are developed. This new method is very general and when tailored towards relativistically moving targets not being limited by the focusability (Rayleigh length) of the laser, while it does not require a waveguide. In a theoretical investigation of Thomson scattering, the optical analogue of undulator radiation, the limits of Thomson sources in scaling towards higher peak brilliances are highlighted. This leads to a novel method for generating brilliant, highly tunable X-ray sources, which is highly energy efficient by circumventing the laser Rayleigh limit through a novel traveling-wave Thomson scattering (TWTS) geometry. This new method suggests increases in X-ray photon yields of 2-3 orders of magnitudes using existing lasers and a way towards efficient, optical undulators to drive a free-electron laser. The results presented here extend far beyond the scope of this work. The possibility to use lasers as particle accelerators, as well as optical undulators, leads to very compact and energy efficient synchrotron sources. The resulting monoenergetic radiation of high brilliance in a range from extreme ultraviolet (EUV) to hard X-ray radiation is of fundamental importance for basic research, medical applications, material and life sciences and is going to significantly contribute to a new generation of radiation sources and free-electron lasers (FELs).

Im Rahmen experimenteller Untersuchungen wurden Stahlbetonplatten hergestellt, mit verschiedenen textilen Bewehrungen verstärkt, mit 125 % Gebrauchslast vorgeschädigt und anschließend unter Gebrauchslast mit einer Brandbelastung nach der Einheitstemperaturkurve (ISO-834, Cellulosic curve) beaufschlagt. Alle Platten hielten der Brandbelastung bei gleichzeitiger Biegebeanspruchung mehr als 60 Minuten stand und zeigten weder Betonabplatzungen noch andere optische Schädigungen auf. Die für dieses überraschend positive Ergebnis verantwortlichen Mechanismen werden diskutiert, sind aber noch nicht vollständig verstanden. Eine Schlüsselrolle spielt dabei vermutlich das gute Rissverhalten von Textilbeton und interne Umlagerungen zwischen Textil und Stahlbewehrung.

This research was aimed at the optimisation of the usability of content-rich computer and mobile based e-learning material. The goal was to preserve the advantages of paper based material in designing optimised modules that were mobile and computer-based, but at the same time avoiding the pitfalls of converting traditional paper based learning material for use on screen. A mobile eye tracker was used to analyse how students studied similar course content on paper, and on mobile device. Screen based eye tracking was also used to analyse how participants studied corresponding content on a desktop screen. Eye movements which were recorded by an eye tracker revealed the sequences of fixations and saccades on the text that was read by each participant. By analysing and comparing the eye gaze patterns of students reading the same content on three different delivery platforms, the differences between these platforms were identified in terms of their delivery of content rich, text based study material. The results showed that more students read online content on a computer screen than on mobile devices. The inferential analysis revealed that the differences in reading duration, comprehension, linearity and fixation count on the three platforms were insignificant. There were significant differences in saccade length. This analysis was used to identify strong aspects of the respective platforms and consequently derive guidelines for using these aspects optimally to design content rich material for delivery on computer screen and mobile device. The limitations of each platform were revealed and guidelines for avoiding these were derived / Computing / M. Sc. (Computing)

Introducing more intermittent renewable energy sources in the energy system makes the role of balancing power more important. Furthermore, an increased infeed from intermittent renewable energy sources also has the effect of creating lower and more volatile electricity prices. Hence, investing in balancing power is prone to high risks with respect to expected profits, which is why a good representation of electricity prices is vital in order to motivate future investments. We propose a stochastic multi-factor model to be used for simulating the long-run dynamics of electricity prices as input to investment valuation of power generation assets. In particular, the proposed model is used to assess the impact of electricity price dynamics on investment decisions with respect to balancing power generation, where a combined heat and power plant is studied in detail. Since the main goal of the framework is to create a long-term representation of electricity prices so that the distributional characteristics of electricity prices are maintained, commonly cited as seasonality, mean reversion and spikes, the model is evaluated in terms of yearly duration which describes the distribution of electricity prices over time. The core aspects of the framework are derived from the mean-reverting Pilipovic model of commodity prices, but where we extend the assumptions in a multi-factor framework by adding a functional link to the supply- and demand for power as well as outdoor temperature. On average, using the proposed model as a way to represent future prices yields a maximum 9 percent overand underprediction of duration respectively, a result far better than those obtained by simpler models such as a seasonal profile or mean estimates which do not incorporate the full characteristics of electricity prices. Using the different aspects of the model, we show that variations of electricity prices have a large impact on the investment decision with respect to balancing power. The realized value of the flexibility to produce electricity in a combined heat and power plant is calculated, which yields a valuation close to historical realized values. Compared with simpler models, this is a significant improvement. Finally, we show that by including characteristics such as non-constant volatility and spiky behavior in investment decisions, the expected value of balancing power generators, such as combined heat and power plants, increases. / I takt med att fler intermittenta förnyelsebara energikällor tillför el i dagens energisystem, blir också balanskraftens roll i dessa system allt viktigare. Vidare så har en ökning av andelen intermittenta förnyelsebara energikällor även effekten att de bidrar till lägre men också mer volatila elpriser. Därmed är även investeringar i balanskraft kopplade till stora risker med avseende på förväntade vinster, vilket gör att en god representation av elpriser är central vid investeringsbeslut. Vi föreslår en stokastisk flerfaktormodell för att simulera den långsiktiga dynamiken i elpriser som bas för värdering av generatortillgångar. Mer specifikt används modellen till att utvärdera effekten av elprisers dynamik på investeringsbeslut med avseende på balanskraft, där ett kraftvärmeverk studeras i detalj. Eftersom huvudmålet med ramverket är att skapa en långsiktig representation av elpriser så att deras fördelningsmässiga karakteristika bevaras, vilket i litteraturen citeras som regression mot medelvärde, säsongsvariationer, hög volatilitet och spikar, så utvärderas modellen i termer av årlig prisvaraktighet som beskriver fördelningen av elpriser över tid. Kärnan i ramverket utgår från Pilipovic-modellen av råvarupriser, men där vi utvecklar antaganden i ett flerfaktorramverk genom att lägga till en länkfunktion till tillgång- och efterfrågan på el samt utomhustemperatur. Vid användande av modellen som ett sätt att representera framtida priser, fås en maximal över- och underprediktion av prisvaraktighet om 9 procent, ett resultat som är bättre än det som ges av enklare modellering såsom säsongsprofiler eller enkla medelvärdesestimat som inte tar hänsyn till elprisernas fulla karakteristika. Till sist visar vi med modellens olika komponenter att variationer i elpriser, och därmed antaganden som används i långsiktig modellering, har stor betydelse med avseende på investeringsbeslut i balanskraft. Det realiserade värdet av flexibiliteten att producera el för ett kraftvärmeverk beräknas, vilket ger en värdering nära faktiska realiserade värden baserade på historiska priser och som enklare modeller inte kan konkurrera med. Slutligen visar detta också att inkluderandet av icke-konstant volatilitet och spikkarakteristika i investeringsbeslut ger ett högre förväntat värde av tillgångar som kan producera balanskraft, såsom kraftvärmeverk.

This licentiate thesis studies the differences between analogue and digital council meetings in how they are organized and how speaking times are distributed between men and women, and hard and soft issues. The study is based on Swedish municipal council meetings, which share similar features with national parliamentary meetings and seek legitimacy through meetings and debate. Perspectives on meeting sites and components are combined with a time perspective on parliamentary activity, where women's representation and formal meeting procedures are set in focus. By studying video recordings of six council meetings in three municipalities, time is used to measure components of three analogue and three digital meetings. Measures of relative speaking time or speech duration are constructed and applied to meeting structure and how women and men spend their speaking time. Findings indicate that the roles of meeting secretaries and chairmen changed when faced with new digital challenges. The meeting formality decreased in the digital meetings, which is in line with previous research. Women generally accounted for a smaller proportion of speaking time in relation to their numerical representation. They spent more of their speaking time debating soft issues, such as social care, while men spent more of their speaking time debating hard issues, such as economy and infrastructure. The findings are in line with previous research on the policy areas with which women and men most engage. In the digital meetings, differences between men and women where still observed, but less noticeable. This could be interpreted as the digital format having potential benefits for women's representation in certain circumstances. The findings have implications for the understanding on how digital parliamentary meetings strive to create legitimacy. However, more research is needed to be able to generalize beyond the specific context of this study and to understand the mechanisms that can explain differences between men's and women's speaking time. The contribution of the thesis lies primarily in the development of a new method for measuring speaking time which, in relation to previous research, presents greater robustness from a reliability and validity perspective. / Den här uppsatsen studerar skillnader mellan analoga och digitala fullmäktigemöten avseende hur de organiseras och hur talartider fördelas mellan män och kvinnor och hårda och mjuka frågor. Studien tar avstamp i fullmäktige som ett parlamentariskt möte på lokal nivå som söker genomflödeslegitimitet genom att sammanträda och debattera. Teoretiska perspektiv på mötesplatser och möteskomponenter kombineras med ett tidsperspektiv på parlamentarisk aktivitet där kvinnors representation och mötesprocedurer fokuseras. Genom att studera videoinspelningar av sex fullmäktigemöten i tre kommuner mäts hur tiden används i tre analoga och tre digitala möten. Måttet talartid konstrueras för att studera hur mötestiden struktureras och hur kvinnor och män spenderar sin talartid. Resultatet pekar på att mötessekreterares och ordförandes roller förändras när de ställs inför nya utmaningar i digitala möten och att formalitetsnivån sjunker i de digitala mötena, vilket är i linje med tidigare forskning om digitala möten. Kvinnor stod generellt för en mindre andel av talartiden i relation till deras numerära representation. De spenderade mer av sin talartid att debattera mjuka frågor som exempelvis social omsorg, medan männen spenderade mer av sin talartid åt att debattera hårda frågor som exempelvis ekonomi och infrastruktur. Resultatet är i linje med tidigare forskning om vilka politikområden som kvinnor och män engageras i. Skillnaderna bestod i de digitala fullmäktigesammanträdena, men de var inte lika påtagliga. En tolkning är att det digitala formatet kan gynna kvinnors representation under vissa omständigheter. Resultatet har implikationer för förståelsen om hur digitala parlamentariska möten bidrar till legitimitet. Dock behövs mer forskning för att kunna generalisera dessa fall bortom den specifika kontexten samt att förstå vilka mekanismer som kan förklara skillnader mellan män och kvinnors talartid. Uppsatsens bidrag ligger främst i utvecklingen av en innovativ metod för att mäta talartid som i relation till tidigare försök står sig robust utifrån ett reliabilitets- och validitetsperspektiv.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis proposes a family of non-isolated bidirectional converter in order to interface dc and ac variables. Such power electronics solutions guarantee: (i) bidirectional power flow between dc and ac converter sides, (ii) independent control in both converter sides, (iii) high level of integration with a reduction of one power switch and its drive circuits, (iv) implementation of two functions by using a unique power conversion stage and (v) reduction of the capacitor losses. Despite proposing new power converter solutions, this thesis presents an analysis of the converters in terms of pulse-width-modulation (PWM) strategy, dc-link capacitor variables, and suitable a control approach. Solutions for single-phase, three-phase and three-phase four-wire systems are proposed by employing a converter leg with three switches. A possible application of this converter is in Vehicle-to-Grid (V2G) systems and interfacing dc microgrid with a utility grid. In addition to the new power electronics converters proposed in this thesis, an experimental setup has been developed for validation of the simulated outcomes. The proof-of-concept experimental setup is constituted by: DSP, Drivers & Integrating Board, Power Supply and, Power Converter & Heat-Sink .

No description available.

True market prices of real estates, unlike bid prices, are often hard to reach. Nevertheless, this information is necessary for many direct and indirect real estate market subjects, especially for valuation purposes. Therefore the bid prices of concrete real estates are often used, but they are not generally equivalent market prices. And so it´s necessary to find some way to convert bid prices to market prices. This dissertation thesis shows definite approach to this issue. Market price and bid price rate is estimated by multi-dimensional linear regression model and non-linear estimations of simple regression. Multi-dimensional linear regression model estimates the values of this rate from other variables, like supply duration, price line according to localities and other. Non-linear estimations of regression function were used for the trend bid and market price modelling in dependence on number of the population in various localities.

This thesis examines the impact of external actors’ involvement on regional organizations’ mediation duration. Focusing on the context of Africa, the study employs a qualitative comparative analysis of two mediation cases to explore the causal relationship between extensive external actors’ involvement and mediation duration. The analysis draws on vastly collected qualitative data from various sources, including reports, news articles, practitioners’ memoirs, and other relevant publications. The finding reveals that extensive external actors’ involvement in regional organizations’ mediation process prolonged mediation duration, while modest external actors’ involvement is linked to a relatively shorter mediation duration. The prolonged mediation duration is attributed to factors such as competition among external actors, coordination challenges, lack of timely decision-making, and the initiation of parallel mediations. The implication of the findings contributes to a better understanding of the dynamics between external actors’ involvement and regional organizations’ mediation processes. It highlights the need for effective cooperation of external actors to enhance regional organizations’ mediation efficiency.

A traumatic brain injury is usually caused by a direct impact to the head and is a common cause of disability and death all around the world. The most effective method to predict brain injury today, is to use a finite element head model. In this investigation, the three injury predictors strain, strain rate, and the product of strain and strain rate were investigated using a rat brain finite element model. The main goal was to find which injury predictor most effectively would predict injury. To find the injury predictor with the highest area under curve value, comparisons between experimental results obtained from simulations and results from previously performed experiments on rats were made. To better understand how different factors can affect the severity of symptoms from a traumatic brain injury, a parametric study with a focus on rotational direction and rotational duration was conducted. Simulations were run on a rat brain finite element model for three rotational directions and three rotational durations.  The statistical analysis was completed for six experiments and nine brain regions. The three injury predictors were extracted from 26 simulations completed on a rat brain finite element model, and the maximum values of the 95th percentile for each brain region were extracted. The results showed that the product of the strain and the strain rate was the most effective injury predictor for four out of six experiments (unconscious time, EPM arm change, EPM open duration, and MWM session 3). The parametric study investigated rotation in the axial, coronal, and sagittal plane against the three rotational durations 1.5 ms, 3 ms, and 6 ms. The parametric study revealed that both the direction and duration of rotation importantly influence the extent of damage in traumatic brain injuries. The results showed that rotation in the axial plane and a 3 ms duration caused the most brain damage. It was also concluded that the results need to undergo additional verification to further define the relationships between the rotational direction, the rotational duration, and the injury predictors. / En traumatisk hjärnskada orsakas vanligtvis av våld mot huvudet och är en vanlig orsak till både funktionsnedsättningar och dödsfall världen över. Den effektivastemetoden för att kunna förutsäga en hjärnskada idag är att använda en finit elementmetodmodell av en hjärna.  I denna undersökning har de tre skadeprediktorerna belastning, belastningshastighet och produkten av belastningen och belastningshastigheten undersöktes med hjälp av simuleringar genomförda på en modell av en råtthjärna, byggd med hjälp av finita elementmetoden. Målet var att ta reda på vilken skadeprediktor som mest effektivt kunde förutsäga hjärnskada. För att hitta skadeprediktorn med högst area under curve-värde gjordes jämförelser mellan experimentella resultat från simuleringar mot resultat från tidigare utförda experiment på råttor. För att få en djupare förståelse för vilka parametrar som kan påverka graden av symptom från en traumatisk hjärnskada genomfördes en parametrisk studie med fokus på rotationsriktning och rotationstid. Nya simuleringar genomfördes på en finit elementmodell av en råtthjärna i tre rotationsriktningar och under tre rotationstider.  Den statistiska analysen utfördes på sex experiment och för nio regioner i hjärnan. Belastningen, belastningshastigheten samt produkten av belastningen och belastningshastigheten extraherades från 26 simulerade finita element råtthjärnor och maximumvärdet från den 95.e percentilen sparades. Resultatet av den statistiska analysen visade att produkten av belastningen och belastningshastigheten var den skadeprediktorn med bäst skadeförutsägelse för fyra av sex experiment(medvetslös tid, EPM arm förflyttning, EPM varaktighet i öppet utrymme och MWM session 3). Under den parametriska studien undersöktes axial, koronal och sagittal rotationsriktning mot de tre rotationstiderna 1.5 ms, 3 ms och 6 ms. Resultatet av den parametriska studien visade att både rotationsriktning och rotationstid spelar viktiga roller när det kommer till omfattningen av symptom som kan uppstå vid en traumatisk hjärnskada. För de undersökta delarna av hjärnan var den rotationsriktning som orsakade störst skada rotation i det axiala planet och den rotationstid som orsakade mest skada var vid 3 ms. Slutsatsen att resultatet bör genomgå ytterligare verifiering drogs. Detta för att ytterligare definiera sambanden mellan rotationsriktning, rotationstid och skadeprediktorerna.