京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18388号 / エネ博第300号 / 新制||エネ||62(附属図書館) / 31246 / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 小西 哲之, 教授 宇根﨑 博信, 准教授 笠田 竜太 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Fusion Science and Technologyの条件：出版後6ヶ月内は掲載不可、ANS Scientific Publicationsを引用すること・ANSのwebsiteへのリンクを付けること、ボリューム番号・ページ番号・イシュウと年も含めること、Copyrigh (date) by the American Nuclear Society, La Grange Park, Illinois.を述べること。 / 京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19827号 / エネ博第333号 / 新制||エネ||67(附属図書館) / 32863 / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 長﨑 百伸, 教授 小西 哲之, 教授 水内 亨 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

Abstract Background Even though the topic of shared leadership has been thoroughly investigated throughout recent years in research, limited literature has focused on this process in the context of new ventures. Moreover, to the knowledge of the authors of this paper, no previous literature has explored how shared leadership evolves as new ventures go through the different phases of the entrepreneurial process, and new members join the team. Purpose The purpose of this study is to investigate the functioning and practice of shared leadership within new venture teams, and to explore if, how and why shared leadership evolves throughout the life cycle of new ventures as the size of the entrepreneurial team changes. Method This study adopted a qualitative approach. A total of nine semi-structured interviews (six co-founders from different new ventures and three new employees) were conducted and transcribed. The collected data was analyzed using template analysis, presented in the empirical findings, discussed in relation to the frame of reference in the discussion, and finally summarized in the conclusion. Conclusion Shared leadership continues to be essential throughout all of the phases of the entrepreneurial process. In the ideation phase, shared leadership is necessary as the different co-founders have different skills and experiences, and different individuals took charge at different times based on their expertise. Shared leadership continued to be essential in the start-up phase as new employees were hired to fill the knowledge-gaps in the new ventures. As the size of the new ventures was still rather small, it was still possible to involve most of the employees in the decision-making. As the size of the new ventures increased and they reached the growth phase, organizational restructuring was necessary and shared leadership was exercised in a different manner. A management team utilized shared leadership to take over-all decisions, the members of the management teams oversaw functional teams, and in those functional teams, shared leadership was utilized.

With the desire for conventional coal-fired power plants to perform flexible operations, the impact of this operation has become important to the field of steam turbine modelling. This study sought to develop a computationally inexpensive turbine model with minimal OEM intervention in order to predict the internal clearances of high-pressure and intermediate-pressure turbines from Eskom's current turbine fleet. The study saw the utilisation of the Nozzle Analogy theory to develop a 1D multistage turbine thermofluid model as well as the development of a representative 1D turbine process model in order to predict the internal temperature gradients promoted within a steam turbine during transient operation. From this model a further 3D FEA turbine model of both the HP and IP turbine units were developed from simple turbine diagrams to apply the predicted temperature boundaries and predict the thermal and structural response of turbine components during transient loading during a full Cold Start procedure. The result of this study was the successful validation of the 1D and 3D Turbine models against plant data from the candidate unit. This was in the form of known process data of unit performance, as well as thermocouple and differential expansion data taken from sensors housed on the turbine unit itself. Through the validation of these parameters, various calibrations techniques were developed over the course of the study with these techniques allowing investigators to gain insight into turbine aging, operator intervention as well as brought turbine component response. The successful establishment of the paired turbine model allowed investigators to evaluate the cold clearances defined during construction and maintenance of these turbine units in industry, which contributes greatly to the availability and efficiency of the unit during these transient operations. Additionally, the establishment of this model allowed for the investigation of the role that start up speed has on turbine component response. This study demonstrated that the development of such a modelling methodology was possible and yielded results with were accurate and insightful in understanding turbine component responses which are otherwise impossible to measure during real-world operation.

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Even though growth hacking is a new concept, it has become a buzz-word among entrepreneurs and start-ups. Various startups that have achieved extensive growth, such as Dropbox, Uber, Airbnb, have been sharing their success stories. However, to date, the focus of this concept was more on the practicalities instead of the theoretical research. With so many start-ups that fail to grow, it is important to research growth methodologies, that can help young entrepreneurs to successfully establish themselves. This paper studies growth hacking concept, by trying to understand how the growth hacking strategy works and how it could be used to retain a user-base in a start-up. With the help of an extensive literature review, interviews with the entrepreneurs and a case study analysis, this research provides (1) insights into the theory of growth hacking and retention marketing,(2) examples of its practices, and (3) an implementation of suggestions made based on the findings. The results of this study indicate that growth hacking is a broad concept and has numerous interpretations. Growth hacking framework has been applied at the early stages of start-ups, however, the growth hacking concept has not been defined as well as it has not been determined whether it is a relevant method to improve user retention. In this study, it was discovered that growth hacking practices can improve to set up theuser retention strategy. However, growth hacking strategies must be tailored and adapted to the entrepreneurial venture’s business model. / Även om growth hacking är ett nytt koncept, har det blivit ett buzz-word bland företagare och nystartade företag. Olika nystartade företag som använt growth hacking och uppnått omfattande tillväxt t.ex Dropbox, Uber och Airbnb har alla förmedlat sina framgångshistorier. Men hittills har fokus legat mer på det praktiska i stället för den teoretiska forskningen. Med så många nystartade företag som inte lyckas växa, är det viktigt att undersöka tillväxtmetodik, som kan hjälpa unga företagare att framgångsrikt etablera sig. Denna uppsats studerar growth hacking konceptet, genom att försöka förstå hur denna strategi fungerar och hur det kunde användas för att behålla en användarbas. Med hjälp av en omfattande litteraturgenomgång, intervjuer med företagare och en fallstudie, ger denna forskning (1) insikter i teorin om growth hacking och retention marknadsföring, (2) exempel på dess praxis, och (3) en implementering av förslag har gjorts baserat på resultaten. Resultaten av denna studie visar att growth hacking är ett brett begrepp och har många tolkningar. Growth hacking ramverk har tillämpats i tidiga stadier på nystartade företag, dock har growth hacking koncept inte definierats, liksom har det inte fastställts huruvida det är en relevant metod för att förbättra användarbevarande. I denna studie upptäcktes det att growth hacking metoder kan förbättra utvecklingen av strategier för bibehållning av användare. Dock måste growth hacking strategier vara skräddarsydda och anpassade till det entreprenöriella företagets affärsmodell.

Att arbeta hållbart blir allt viktigare, inte minst i byggbranschen som länge har kämpat för att skapa säkra arbetsplatser. För att vara en attraktiv arbetsgivare måste företag arbeta med hållbarhet ur fler aspekter av sina anställdas hälsa. Tillsammans med ökade krav på hållbarhet ökar även förväntningarna på mående på arbetsplatsen. Företag har goda skäl att ta hänsyn till detta även ur en produktivitetssynpunkt då forskning visat både att arbetet påverkar hur anställda mår och att deras mående påverkar deras prestation och i förlängningen projektets produktivitet. Studiens syfte är att bättre förstå hur projektorganisationer och dess medlemmar arbetar för att etablera socialt hållbara arbetsprocesser i uppstarten av produktion i ett infrastrukturprojekt. För att göra det kommer framväxten av rutiner samt vilka konsekvenser tröghet och splittring får för projektmedlemmarna studeras med fokus på välmående. I en kvalitativ intervjustudie undersöktes uppstarten av produktion i tre infrastrukturprojekt i Stockholm. Det visade sig att välmående och andra mjuka parametrar är mycket viktiga för projektens medlemmar och att rutiner i uppstarten av produktion inte reflekterar det. En del av orsaken kan förklaras ur ett rutinperspektiv: organisationen har en tröghet som gör det svårt för dem att byta ut sina rutiner och en ibland även splittring som gör det svårt att komma överens om gemensamma rutiner. Det är lättare för projektmedlemmarna att arbeta mot kortsiktiga mål än mot långsiktiga mål vilket blir tydligt när det kommer till arbete med välmående och andra mjuka parametrar. / Working sustainably is becoming significantly more important, especially in the construction industry which has struggled to create safe working environments for a long time. In order to be an attractive employer companies must work with sustainability from many aspects of their employees’ health. Sustainability demands have increased along with expectations of well-being in the workplace. Companies have reason to consider this also from a productivity perspective, research has shown that work affects the well-being of employees and well-being affects their performance which in turn affects project productivity. The purpose of this study is to better understand how project organizations and its members work to establish socially sustainable work processes in the start-up of production in an infrastructure project. To do so the development of routines along with the consequences of inertia and fragmentation have on the members of the project will be investigated, with a focus on well-being. In a qualitative interview study, the start of production in three infrastructure projects in Stockholm were investigated. It turned out that well-being and other soft parameters are very important to the project members and that project routines in the start of production do not reflect that. Partly the reasons for this can be explained from a routine perspective: the organization contains inertia which makes it difficult for them to change routines, in some cases they are also fragmented which makes it difficult to agree upon common routines. It is easier for the members of the projects to work towards short term goals than long term goals, which becomes clear when it comes to work aimed towards well-being and other soft parameters.

Due to the adverse effects of ammonia on the environment, many governments, including Canada, have imposed new regulations to reduce the discharge of ammonia wastewater effluent into natural receiving waters, which has resulted in the upgrade of ammonia removal at water resource recovery facilities (WRRFs) across the world. There is therefore a need to investigate present urban/peri-urban and rural challenges associated with municipal total ammonia (TAN) removal. In particular, there is a need to further advance and optimize technologies such as the moving bed biofilm reactor (MBBR) to meet these critical challenges. The first objective of this thesis is to validate an elevated loaded strategy for partial nitritation (PN) MBBR as an application for mainstream urban and peri-urban municipal wastewater treatment and to elucidate the mechanism of nitrite-oxidation suppression of this system. The second objective is to identify practical storage strategies for nitrifying MBBR units as rural municipal wastewater upgrade systems (lagoon systems), optimizing the TAN removal performance during seasonal discharge periods. In the context of the present climate change crisis and sustainable development requirements, there is an increased need for efficient TAN removal from urban and peri-urban municipal wastewaters. The application of the energy and cost-efficient partial nitritation/anammox (PN/A) technology to mainstream urban and peri-urban municipal wastewater can prove challenging because of limited ability to achieve the stable PN. Hence, there is a need for the validation of the present strategies for achieving effective and stable PN in the mainstream portion of conventional urban and peri urban WRRFs. The 45 days operation of a laboratory-scale, elevated loaded PN MBBR with average surface area loading rate (SALR) of 5.2 ± 0.1 g TAN/m²·d and a hydraulic retention time of 2h showed a successful and stable nitrite accumulation. The average surface area removal rate (SARR) of 2.3 ± 0.2 g TAN/m²·d (theoretical performance objective of 2.7 g TAN/m²·d), TAN removal efficiency of 43.1 ± 3.4% (theoretical performance objective of 53%) and NO₂- / (NO₂- + NO₃-) ratio of 82.4 ± 4.8% (theoretical performance objective of 100%) meets the necessary requirement to support subsequent cost-efficient anammox process. Biofilm analyses of the laboratory-scale, elevated loaded PN MBBR indicated that the attached biofilm was thick and dense, stable biofilm that did not show and biofilm loss or washout. Biofilm cell viability analyses was indicative of an active biofilm. The ratio of AmoA gene targets of the ammonia oxidizing bacteria (AOB) in the MBBR biofilm to the targeted gene region of the Nitrospira nitrite oxidizing bacteria (NOB) population demonstrates that NOB activity suppression of this technology was the dominant mechanism of nitrite-oxidation in the elevated loaded PN MBBR system. In North America, the TAN removal performance of waste stabilization ponds (also termed wastewater treatment lagoon systems), which are widely applied as rural WRRFs, is often not stable due to seasonal temperature variations. Nitrifying MBBR as an upgrade TAN removal unit has been successfully applied to improve TAN removal during winter. However, re-seeding the nitrifying MBBR biofilm during each seasonal operation period is not sustainable. There is therefore an urgent need for optimizing storage strategies of nitrifying MBBR carriers when used as TAN removal upgrade systems of rural WRRFs. The study of storage strategies for nitrifying MBBR as lagoon upgrading systems indicated the batch storage of the nitrifying MBBR biofilms with intermittent aeration could be an effective storage strategy for short-term (12 weeks) storage. Carriers stored in continuous flow aerated condition was shown to be the second most suitable storage method for nitrifying MBBR carriers for systems exposed to less than 12 weeks of storage. Carriers stored in dry condition, batch aerated conditions without flow, and continuous flow aerated condition for long-term (over 18 weeks) failed to achieve full nitrification following 18 days of operation conditions. Carriers stored in dry condition did not successfully achieve full nitrification for short-term and long-term storage and may not be applied to store full nitrification MBBR carriers. The study suggested that, compared to re-seeding start up strategy of the lagoon upgrading nitrifying MBBR biofilm, the use of the appropriate storage strategies, such as batch aerated conditions without flow, has the potential to shorten the start-up time and save energy during the non-discharge periods.

Organisational culture is a complex phenomenon that has received a lot of attention in research. Nevertheless, most of the studies on organisational culture concern the traditional organisation and there is a lack of research on how organisational culture is perceived in a start-up. Therefore, this study aims at examining the stories of organisational members working in a start-up operating seasonally. The study reveals that flexibility is perceived as a main principle of the organisation, and dives deeper into what flexibility represents for this type of the business. The flexibility is two-fold and is perceived as favourable but the organisational members also acknowledge disadvantages of flexible working and identify chaos and stress as the main disadvantage. This qualitative immersive study explains why flexibility as the principle of the business might sabotage the growth of the organisation. The study contributes to deeper understanding of organisational culture and its influence on effectiveness, understanding of what it means to be a start-up, and provides insights on challenges that start-ups operating seasonally need to deal with.

The bi-directional dc/dc converter is a very popular and effective tool for alternative energy applications. One way it can be utilized is to charge and discharge batteries used in residential solar energy systems. In the day, excess power from the PV panels is used to charge the batteries. During the night, the charged batteries will power the dc bus for loads in the house such as home appliances. The dual active bridge (DAB) converter is very useful because of its high power capability and efficiency. Its symmetry is effective in transferring power in both directions. However, the DAB converter has drawbacks in the start-up stage. These drawbacks in boost mode include high in-rush current during start-up, and the fact that the high side voltage cannot be lower than the low side voltage. A popular existing method to alleviate this problem is the use of an active clamp and a flyback transformer in the circuit topology to charge the high side before the converter is switched into normal boost operation. The active clamp not only helps eliminate the transient spike caused by the transformer leakage, but also continues to be used during steady state. However, this method introduces a new current spike occurring when the converter transitions from start-up mode to boost mode. To alleviate this new setback, an additional transitional stage is proposed to significantly reduce the current spike without the use of any additional components. The converter is current-fed on the low side, and voltage-fed on the high side. A simple phase shift control is used in buck mode and PWM control is used during the boost mode for both the start-up mode and the normal boost operation. This thesis discusses the performance results of a 48-400 V dc/dc converter with 1000 W power output. / Master of Science