Computer simulation of H and He effects in fusion reactor materials

Fusion power is an appealing source of clean and abundant energy. The radiation resistance of reactor materials is one of the greatest obstacles on the path towards commercial fusion power. These materials are subject to a harsh radiation environment, and cannot fail mechanically or contaminate the fusion plasma. Moreover, for a power plant to be economically viable, the reactor materials must withstand long operation times, with little maintenance. The fusion reactor materials will contain hydrogen and helium, due to deposition from the plasma and nuclear reactions because of energetic neutron irradiation. The first wall divertor materials, carbon and tungsten in existing and planned test reactors, will be subject to intense bombardment of low energy deuterium and helium, which erodes and modifies the surface. All reactor materials, including the structural steel, will suffer irradiation of high energy neutrons, causing displacement cascade damage. Molecular dynamics simulation is a valuable tool for studying irradiation phenomena, such as surface bombardment and the onset of primary damage due to displacement cascades. The governing mechanisms are on the atomic level, and hence not easily studied experimentally. In order to model materials, interatomic potentials are needed to describe the interaction between the atoms. In this thesis, new interatomic potentials were developed for the tungsten-carbon-hydrogen system and for iron-helium and chromium-helium. Thus, the study of previously inaccessible systems was made possible, in particular the effect of H and He on radiation damage. The potentials were based on experimental and ab initio data from the literature, as well as density-functional theory calculations performed in this work. As a model for ferritic steel, iron-chromium with 10% Cr was studied. The difference between Fe and FeCr was shown to be negligible for threshold displacement energies. The properties of small He and He-vacancy clusters in Fe and FeCr were also investigated. The clusters were found to be more mobile and dissociate more rapidly than previously assumed, and the effect of Cr was small. The primary damage formed by displacement cascades was found to be heavily influenced by the presence of He, both in FeCr and W. Many important issues with fusion reactor materials remain poorly understood, and will require a huge effort by the international community. The development of potential models for new materials and the simulations performed in this thesis reveal many interesting features, but also serve as a platform for further studies.Fusionskraft är en lockande framtida energikälla, eftersom den är ren, säker och i praktiken outsinlig. De kärnfysikaliska processerna är väl kända och med dagens och kommande testreaktorer är man nära att visa att ett fusionskraftverk är möjligt. Ett av de största återstående problemen är dock att konstruera väggmaterial som tål den extrema strålningen i en fusionsreaktor. För att fusionskraft skall bli kommersiellt lönsam bör reaktorväggarna hålla i långa tider med så lite underhåll som möjligt. I den reaktortyp som är längst utvecklad för ett kraftverk, tokamakreaktorn, innesluts den heta fusionsplasman av toroidala magnetfält. Läckaget från plasman styrs mot en s.k. divertor, som är designad för den intensiva strålningen av väteisotoper och helium. Denna strålning kan förändra ytans egenskaper och orsaka erosion av ytmaterial. Hela reaktorn kommer också att bestrålas av högenergetiska neutroner från fusionsprocessen. Dessa leder till kärnreaktioner i väggarna och skador genom kollisionskaskader. Väteisotoper och helium finns i fusionsreaktormaterialen både p.g.a. deposition från fusionsplasman och kärnreaktioner från neutronstrålningen. Väte och heliums inverkan på materialens egenskaper är därmed ett viktigt forskningsområde. Många av mekanismerna som styr uppkomsten av strålningsskador sker på atomnivå och på kort tidsskala, vilka är svårtillgängliga experimentellt, men lämpliga för molekyldynamiska simuleringar. I simuleringarna beskrivs växelverkan mellan atomer med hjälp av potentialer. Kvaliteten på potentialerna är avgörande för hur tillförlitliga simuleringarna är. I denna avhandling har nya potentialer utvecklats för system med volfram, väte och kol, samt helium i järn och krom. Volfram och kol används som divertormaterial, medan järn och krom är huvudbeståndsdelarna i stålet som används i reaktorn. Dessa potentialer gör det möjligt att studera system som tidigare inte var tillgängliga för molekyldynamiska simuleringar. Potentialerna är baserade på litteraturdata från experiment och elektronstrukturberäkningar, samt egna elektronstrukturberäkningar. I avhandlingen presenteras resultat som visar att helium har en betydande effekt på uppkomsten av strålningsskador i järnkrom och volfram, medan kroms inverkan på den energi som krävs för att flytta en atom från sin plats i järnkrom är obetydlig. Bildningen och migrationen av små heliumklustrar och helium-vakansklustrar har undersökts i järn och järnkrom, med resultatet att klustrarna kan vara betydligt mer rörliga än vad man tidigare har antagit

Complementing a Kaplan hydropower turbine with a battery energy storage : BESS sizing for shared FCR-N market participation and reduction of turbine control movements

Pohjoismaisen sähköjärjestelmän sähkönlaatu on huonontunut viime vuosikymmenten aikana ja samalla normaalin taajuusalueen ulkopuolella vietetty aika on kasvanut. Verkkoon liittyy tulevaisuudessa entistä enemmän uusiutuvaa energiaa hydyntäviä voimalaitoksia, jotka ovat luonteeltaan epäsäännöllisiä. Tämän työn tarkoituksena on tutkia energiavaraston asentamista Kaplan vesivoimaturbiinin rinnalle. Tämän vuoksi työssä tutkitaan olemassaolevia erilaisia teknologioita energian varastoimiseen. Näistä teknologioista valittiin yksi tähän tarkoitukseen sopiva. Energiavaraston teknologiaksi valittiin Lithium akku. Käytössä olevan vesivoimalaitoksen Kaplan -turbiineja käytiin testaamassa useampaan otteeseen. Näiden testien tarkoituksena oli muun muassa energiavaraston koon mitoittaminen, turbiinisäätimen parametrien testaus ja hienosäätö. Akkuihin perustuva energiavarasto voisi vähentää turbiinin ohjaustarvettu sen osallistuessa taajuusohjattuun käyttöreservikauppaan. Uusi ohjain, joka vastaisi kuorman jakamisesta energiavaraston ja turbiinin välillä on kehitteillä VEO:lla. Tässä työssä ehdotetulle ratkaisulle saatiin arvioitua noin 5 vuoden takaisinmaksuaika investoinneille.The frequency quality of the Nordic power system has deteriorated over the last decades. The number of minutes outside the normal frequency band area has increased. Furthermore, an oscillating behaviour of the grid has been observed with a growing amplitude. This oscillating behaviour increases the control work carried out by the hydropower turbines. One of the main reasons for this development is the growing amount of power generation that is coming from intermittent energy sources, such as wind and solar. The objective of the thesis is to explore the possibility to combine an electrical energy storage to an operational Kaplan turbine hydropower plant. To fulfil the objective, background work on different energy storage technologies was carried out by reviewing different technologies against each other for the sake of finding the most fitting technology for the purpose. A battery energy storage was chosen as the technology for the proposed application. Measurements were made on operational Kaplan turbines to narrow down the scale of needed energy and power output for the electrical energy storage. Tests were carried out on different turbine governor models to find an optimal control scheme for the turbine. A BESS could reduce the control movements of a Kaplan turbine operating in frequency control mode. A new controller that would share the primary frequency control regulation between the turbine and BESS is under development at VEO Oy. The payback time for an in-vestment was found to be approximately 5 years

Internet Addiction, Locus of Control and Resilience

The study investigates the difference in the Locus of Control and Resilience with respect to different levels of Internet Addiction as well as their impact on Internet Addiction among emerging adults. It assesses Internet Addiction levels, investigates the association between Internet Addiction, Locus of Control and Resilience and analyses gender difference. Internet Addiction Test by Young, Locus of Control (LOC-Scale) Scale developed by Rotter (1966) and The Brief Resilience Scale were used. Pearson’s product-moment correlation analysis was used to evaluate the association between Internet Addiction, Locus of Control and Resilience. An independent t-test was used to test whether there is a statistical difference between gender and internet addiction at different levels. One-way ANOVA was used to investigate the gender difference in Internet Addiction, Locus of Control and Resilience respectively. The research findings show that there is a significant relationship between Internet Addiction, Locus of Control and Resilience as well as significant gender difference in Internet Addiction. A significant difference in Resilience among the different levels of Internet Addiction was also found in the study

Market Orientation, Competitive Aggressiveness, and Firm Performance. An Empirical Study

Research in competitive dynamics has largely pertained to the series of competitive moves initiated by a firm to either retaliate or engage rivals to improve market position relative to competitors. In spite of the richness of literature, numerous of gaps remain in the stream of research, particularly in regard to the understanding of how a firm’s continuous creation of superior customer value contributes to competitive dynamics research. This study endeavors to address this gap by investigating the moderating effect of market orientation on the relationship between competitive aggressiveness and firm performance. Drawing upon Narver & Slater’s (1990) perspective of market orientation that underscores the importance cultural dimensions in the creation of superior customer value, this paper proposes that market orientation strengthens the relationship between competitive behaviour and firm performance, as market oriented firms possess superior knowledge to exploit more opportunities compared to competitors and are better equipped to defend market position against rivals. An empirical research is employed to investigate the hypothesized relationships among market orientation, competitive aggressiveness, and firm performance. The data were collected from three sets of survey data administered in 2014, 2016, and 2018 (n = 2008) targeting top management members in Finnish firms with over five employees. The proposed theoretical model of the research was validated with a Confirmatory Factor Analysis (CFA) and the hypothesized relationships were tested with a series of Structural Equation Model (SEM) analyses. Although the results of the study reveal that the direct effect of competitive aggressiveness on financial performance was significant and that market orientation positively influences the relationship between competitive aggressiveness and firm performance, these results were highly contextual in regard to firm size, market position, and market focus. The paper has three main contributions. First, although extant literature has examined the effect of competitive aggressiveness on firm performance, most of these studies have been limited to a single industry, leveraging U.S. centric data samples. This research brings the conversation to the Finnish context, examining firms across various industries, shedding light into a relatively unexplored context in competitive dynamics. Second, this research demonstrates the positive moderating role of market orientation between competitive aggressiveness and firm performance, and responds to calls to integrate market orientation within broader models in strategic management literature. Third, the research extends studies in the field of competitive dynamics by examining robustness of findings in regard to an organization’s market focus, size, and market position

“Beauty is how you feel inside”: Aesthetic judgements are related to emotional responses to contemporary music

While it has extensively been argued that aesthetic categories such as beauty have a direct relationship to emotion, there has only been limited psychological research on the relationship between aesthetic judgements and emotional responses to art. Music is recognised to be an art form that elicits strong emotional responses in listeners and it is therefore pertinent to study empirically how aesthetic judgements relate to emotional responses to music listening. The aim of the presented study is to test for the impact of aesthetic judgement on various psychophysiological response measures of emotion that were assessed in parallel in two contemporary music concerts, each with a different audience and programme. In order to induce different levels of aesthetic judgements in participants, we assigned them randomly to one of two groups in a between-subjects design in both concerts: One group attended a talk on the music presented, illustrating its aesthetic value, while the other group attended an unrelated talk on a non-musical topic. During the concerts, we assessed, from 41 participants in Concert 1 (10 males; mean age 23 years) and 53 in Concert 2 (14 males; mean age 24 years), different emotional response components: a) retrospective rating of emotion; b) activation of the peripheral nervous system (skin conductance and heart rate); c) the activity of two facial muscles associated with emotional valence (only Concert 1). Participants listened to live performances of a selection of contemporary music pieces. After each piece, participants rated the music according to a list of commonly discussed aesthetic judgement criteria, all thought to contribute to the perceived aesthetic value of art. While preconcert talks did not significantly impact value judgement ratings, through factor analyses it was found that aesthetic judgements could be grouped into several underlying dimensions representing analytical, semantic, traditional aesthetic, and typicality values. All dimensions where then subsequently shown to be related to subjective and physiological responses to music. The findings reported in this study contribute to understanding the relationship between aesthetic judgement processes and emotional responses to music. The results give further evidence that cognitive-affective interactions have a significant role in processing music stimuli