Industrial power generation is an ever-changing practice. After the steam turbine was invented energy production developed with accelerated tempo. Coal replaced wood, oil replaced coal and after natural gas started being used as an energy source, no one could even imagine better and cleaner energy technologies. But in the 21st century renewable energy started its development. The western world decided to develop green, environmentally friendlier technologies with a strong desire to become independent form oil and gas exporters. Hydrogen energy and fuel cell technology are two of the most promising fields of energy study. The European Union and the USA regularly invest a lot of money for research in this area and rapidly develop an energy economy that is free from CO2 emissions. In this scientific report, the situation of hydrogen energy systems in the world but also with a large focus on Russia has been investigated. The main focus was made on successful international projects which have been created within last decades. Moreover, hydrogen production methods and fuel cell technology were described in detail. The cost to produce 1 kg of hydrogen gas based off of Russian economic figures and using water electrolysis and steam reforming process was estimated. Solid oxide and polymer electrolyte membrane fuel cells were considered in the analysis. The next step was to estimate effectiveness of combined technology with electrical power of 1 kW and economic feasibility of using such technology as stand-alone power generation system in the regions with decentralized electricity.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This doctoral thesis deals with the study, analysis and development of a new hybrid topology for voltage regulation of stand-alone microgeneration systems employing self-excited induction generators. The hybrid topology proposed considers a three-phase four-wire system and employs a distribution static synchronous compensator (DSTATCOM) in combination with banks of switchable capacitors (BCC) to perform the regulation of the terminal voltages of the induction generator. As a result of using the proposed topology, it is expected the regulation of the amplitude of the terminal voltages of the induction generator, with effective reduction of the power processed by DSTATCOM, regardless of the characteristic of the applied load. Therefore, it is considered the compensation of reactive currents of the system in terms of phase, amplitude and shape, performed by a suitable control system. The control structure applied to control the DSTATCOM and the switching of BCC ensures the regulation of voltages with low harmonic distortion (THD) and reduced distortion factor among voltages, in addition to keeping the generator currents sinusoidal and balanced. This thesis also investigates two distinct forms of frequency control using the electronic load control: (i) auxiliary load controlled by chopper element connected to the DC bus DSTATCOM and (ii) auxiliary load controlled by chopper element connected to the AC bus system through non-controlled three-phase rectifier. Simulation and experimental results are presented to validate and demonstrate the suitable performance of the proposed hybrid topology in the regulation of voltages and system frequency. The system is tested by load transient including three-phase and single-phase loads, linear and non-linear loads, resistive and reactive loads. / Esta tese de doutorado trata do estudo, análise e desenvolvimento de uma nova topologia híbrida de regulação das tensões de sistemas isolados de microgeração empregando geradores de indução auto-excitados. A topologia híbrida proposta considera um sistema trifásico a quatro fios e emprega um compensador síncrono estático de distribuição (DSTATCOM) em associação a bancos de capacitores comutáveis (BCC) para efetuar a regulação das tensões terminais do gerador de indução. Como resultado da utilização da topologia proposta, espera-se a regulação da amplitude das tensões terminais do gerador, com efetiva redução da potência processada pelo DSTATCOM, independentemente da característica da carga aplicada. Considera-se, portanto, a compensação de correntes reativas do sistema em termos de fase, amplitude e forma, realizada a partir de sistema de controle adequado. A estrutura de controle aplicada ao controle do DSTATCOM e à comutação dos BCC, garante a regulação das tensões com reduzida taxa de distorção harmônica (THD) e reduzido fator de desequilíbrio de tensão (FD), além de manter as correntes do gerador senoidais e balanceadas. Neste trabalho também são investigadas duas formas distintas de controle de frequência a partir do controle eletrônico de carga: (i) carga auxiliar controlada por elemento chopper conectada ao barramento CC do DSTATCOM e (ii) carga auxiliar controlada por elemento chopper conectada ao barramento CA do sistema através de retificador trifásico não-controlado. Resultados de simulação e resultados experimentais são apresentados para validar e demonstrar o bom desempenho da topologia híbrida proposta na regulação das tensões e frequência do sistema. O sistema é testado mediante transitórios de cargas trifásicas e monofásicas, lineares e não-lineares, resistivas e reativas.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-03-04T10:45:15Z No. of bitstreams: 1 leandrodamottaborges.pdf: 2242416 bytes, checksum: 10ac80b836250ec857dfe2dc8f819119 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-04-24T01:49:45Z (GMT) No. of bitstreams: 1 leandrodamottaborges.pdf: 2242416 bytes, checksum: 10ac80b836250ec857dfe2dc8f819119 (MD5) / Made available in DSpace on 2016-04-24T01:49:45Z (GMT). No. of bitstreams: 1 leandrodamottaborges.pdf: 2242416 bytes, checksum: 10ac80b836250ec857dfe2dc8f819119 (MD5) Previous issue date: 2013-09-27 / Este trabalho apresenta o estudo, dimensionamento e gestão de um sistema solar fotovoltaico isolado da rede elétrica para alimentar cargas de equipamentos de automação industrial. Um exemplo de aplicação são unidades de comando e sinalização ferroviária que, em alguns casos, são comandadas por relés e, mais atualmente, sendo substituídas por Controladores Lógico Programáveis. No sistema solar fotovoltaico isolado, o excedente de energia elétrica produzida nos painéis solares fotovoltaicos é armazenado em baterias eletroquímicas estacionárias de chumbo-ácido para posterior aproveitamento durante o período noturno e de baixa produção de eletricidade. Esse tipo de bateria apresenta efeito de memória, não pode sofrer descarga profunda ou ser submetida a tensões elevadas. Assim, este trabalho visa especificar e dimensionar um sistema solar fotovoltaico para aplicações em cargas de automação industrial isolados da rede elétrica, bem como assegurar elevada vida útil da bateria eletroquímica de chumbo-ácido sem prejudicar o rastreamento de máxima potência dos painéis solares fotovoltaicos. Para isso, uma estratégia de gestão de energia possibilita alterar o controle do conversor CC-CC que realiza a interconexão entre os painéis solares fotovoltaicos e a bateria eletroquímica. Resultados de simulação computacional apontam para o bom desempenho conceitual do sistema e seu potencial para a aplicação pretendida. / This work presents the study, design and management of a stand-alone photovoltaic system to feed industrial automation load. E examples of application are railway signaling unit controls, which in some cases are controlled by electromechanical relays and more currently being replaced by programmable logical controllers. In a stand-alone photovoltaic system, the excess of electricity produced in the photovoltaic panels is stored in lead-acid stationary electrochemical batteries for later use during the night and low electricity production periods. This kind of battery presents memory effect, cannot have deep discharge or be subjected to high voltages. Thus, this work aims to specify and size a solar photovoltaic system for applications in industrial automation loads isolated from the grid, as well as ensuring longer lifetime to electrochemical battery of lead-acid without harming the maximum power tracker of photovoltaic panels. For this, a strategy for changing power management enables the control of DC-DC converter that performs the interconnection of photovoltaic panels and electrochemical battery. Results of computer simulation indicate the good conceptual performance of the system and its potential for the intended application.

In modern healthcare organizations, work is increasingly team-oriented, which puts pressure on information technology to support staff collaborations. Healthcare organizations are lagging behind in the use of IT and often use outdated systems. A reason for this is the long and cumbersome process of IT-procurement. Stand-alone systems can help such organizations be more efficient, and receptive of the latest technologies, while conveying lower risks, and increased chances of successful implementation. Therefore, this study has investigated what problems can be expected, and how to manage them, when designing such systems. The study was conducted at the Department for Reconstructive Surgery at Karolinska University Hospital. Action research was used, and a system supporting the scheduling of doctors was deigned, implemented and evaluated. The study consists of an initial exploratory phase, a design and implementation phase, and an evaluation phase. The findings of this study indicate that the problems that can be expected when developing a stand-alone system at a small specialized healthcare department are: 1) that the hierarchies among staff may lead to failure to accept designs and the designs not taking all stakeholders into account, 2) that the complexity may lead to an inability to identify the real problems and define appropriate design-goals, and 3) that the combination of 1 and 2 hinders a mutual understanding of design-goals, problems, and solutions. To manage the problems, this study suggests the use of participatory design, user centered system design, and a computer supported collaborative work approach, and provides guidelines for using these to reach an effective implementation. / I moderna sjukhus arbetar man allt mer team-orienterat, vilket ställer krav på system och programvara att stödja samarbeten personalen emellan. Inom sjukvården sker anskaffandet av nya tekniker genom om offentlig upphandling, vilka är tungrodda processer som tar lång tid. Detta leder till att många sjukhus har utdaterade system som inte tjänar organisationernas bästa. Genom att anskaffa mindre, fristående system kan mottagligheten för de senaste teknikerna ökas, och med denna kan även en ökad effektivitet av administrativt arbete uppnås, till låg risk och med möjlighet till effektiv implementation. Av dessa anledningar har denna studie undersökt vilka problem som kan förväntas vid utveckling av sådana system, och hur dessa problem kan överbryggas. Studien utfördes på Kliniken för Rekonstruktiv Plastikkirurgi på Karolinska Sjukhuset i Solna. Vi använde oss av aktionsforskning, och utvecklade, implementerade samt utvärderade ett stödsystem för schemaläggningsprocessen på kliniken. Studien består av tre faser: en explorativ fas, en design- och implementationsfas, samt en utvärderingsfas. Resultaten visar på att de problem som kan förväntas när man utvecklar ett fristående system för en specialiserad kirurgklinik är: 1) att hierarkier inom personalstyrkan kan leda till att utformningen av system inte accepteras, och att system inte bistår alla intressenter, 2) att organisationens komplexitet gör det svårt att identifiera de underliggande problemen, och definiera ändamålsenliga målsättningar för utformningen av systemet, och 3) att kombinationen av 1 och 2 hindrar en ömsesidig förståelse för utformningen av systemet, de problem som finns, och hur man kan lösa dem. Vidare visar denna studie att problemen kan överbryggas genom att använda metoder för deltagande design, användarcentrerad design och en modell för synsätt kallad computer supported collaborative work under designprocessen. Vidare tillhandahåller studien riktlinjer för hur dessa metoder och synsätt kan användas för att uppnå en effektiv implementation.

By 2020, Thailand ensured 100% electricity access to its 72 million inhabitants. This was partly done by promoting off-grid energy systems in rural areas instead of using costly grid extensions. Although electricity is ensured for all, future challenges and objectives include- increasing the share of renewable energy and decreasing energy dependence while simultaneously meeting the increasing demand. Off-grid energy solutions for rural areas have been studied in many previous projects. The most optimal energy system concerning cost, resilience, and emissions can be found by quantifying natural resources, estimating electricity consumption, and comparing technologies. This project aims to evaluate how an existing off-grid system can be complemented in the future. This was done by using the optimization program HOMER. The village Ban Wangwon, located in Prachuap Khiri Khan, was for a long time without electricity access due to a law obstructing them from connecting to the grid. This changed when in 2018, households were mounted with PV and BESS. Energy demand in the village was determined in three scenarios based on the World Banks tier system for rural energy and the previous population growth. In addition, the availability of meteorological and natural resources, energy load profile, and price of technology were determined based on the literature review and a field study. According to the results, the most optimal energy system for today's electricity use, Scenario 1, regarding both cost and emissions, was a PV/BESS system. In scenarios 2 and 3, a PV/BESS/Bio configuration proved the most cost-effective, although not optimal regarding emission rates for future energy demand. However, this system sees much lower emissions compared to when diesel generators were included, which makes this suitable for reaching Ban Wangwons requirements. Using a bio generator optimally requires a centralized energy system, requiring settlements with landowners. The biomass fuel considered in this work was pineapple crowns due to the abundance of pineapple factories and farms in the area. After a sensitivity analysis, the most impactful variables proved to be fuel prices, bio generator efficiency, and discount rate. Only one type of solar panel and battery was considered, and the load was assumed to be constant, which hindered the credibility of the results. Future projects could investigate more thoroughly how pineapple waste can be utilized in energy production, how price changes in renewable energy affect the outcome, and how a microgrid would be constructed. The results were considered beneficial in achieving SDGs 1 No poverty, 7 Affordable and clean energy, 11 Sustainable cities and communities, and 13 Climate action. / År 2020 säkerställde Thailand tillgång till el för 100% av sina 72 miljoner invånare. Detta gjordes delvis genom att främja fristående energisystem på landsbygden istället för att använda dyra elnätsförlängningar. Även om el finns tillgängligt för alla, inkluderar framtida utmaningar och mål att öka andelen förnybar energi samt minska energiberoendet samtidigt som efterfrågan på energi ökar. Fristående energilösningar för landsbygden har studerats i många tidigare projekt. Det mest optimala energisystemet gällande kostnader, resilliens och utsläpp kan bestämmas genom att kvantifiera naturliga resurser, uppskatta elförbrukning och jämföra teknologier. I detta projekt utvärderas hur ett redan befintligt fristående system kan kompletteras i framtiden. Detta gjordes med hjälp av optimeringsprogrammet HOMER. Byn Ban Wangwon, belägen i Prachuap Khiri Khan, var länge utan elektricitet på grund av en lag som hindrade dem från att ansluta till nätet. Detta ändrades när hushåll utrustades med PV och BESS år 2018. Energibehovet i byn bestämdes i tre scenarier baserat på the World Banks tier-system för energi på landsbygden samt den tidigare befolkningsökningen. Meteorologiska och naturliga resurser, energianvändningsprofil och teknikpris bestämdes baserat på en litteratur- och fältstudie. Enligt resultaten var det mest optimala energisystemet för dagens elanvädning, Scenario 1, ett PV/BESS system, avseende både kostnader och utsläpp. För de två övriga framtidsscenariorna, Scenario 2 och 3, visade sig en PV/BESS/Bio-konfiguration vara mest kostnadseffektiv, trots att den medför utsläpp. Detta system har dock mycket lägre utsläpp jämfört med dieselelgeneratorer, vilket gör det bra för att nå Ban Wangwons krav. Tillämpning av en biogenerator skulle kräva ett centraliserat energisystem, vilket skulle kräva överenskommelser med markägare. Biomassan som användes i detta arbete var ananasrester på grund av den stora mängden ananasfabriker och plantager i området. Efter en känslighetsanalys visade sig de mest påverkande variablerna vara bränslepris, bio-generatorns effektivitet och diskonteringsräntan. Endast en typ av solpanel och batteri togs i åtanke och elbehovet antogs vara konstant, vilket hindrar trovärdigheten i resultaten. Hur ananasavfall kan användas i energiproduktionen, hur prisförändringar inom förnybarenergi påverkar resultatet och hur ett microgrid skulle kunna konstrueras är alla relevanta frågor för framtida projekt. Resultaten ansågs vara fördelaktiga för att uppnå FN:s hållbarhetsmål 1 Ingen fattigdom, 7 Hållbar energi för alla, 11 Hållbara städer och samhällen och 13 Bekämpa klimatförändringarna.

As of today, large unused potential for biogas production exist within the Swedish agriculture sector. The biogas production within this sector is, however, associated with several problems such as poor energy efficiency and non-profitable systems. This is to some degree due to lack of standardized technical solutions. International Micro BioGas AB (IMB AB) has been aided by KTH since 2014. This project investigates several innovations from IMB AB in regards to biogas production:  A mixing device  A building capturing waste heat from the digesters (building concept)  Insulation of the digester (cover concept)  Small-scale and modular package systems The innovations listed above are evaluated from energy, economic and environmental perspectives by doing a case study on the dairy farm Ogestad close to Gamleby, Sweden. Two cases are considered. In Case 1, the raw biogas is burned in a combined heat and power-unit (CHP) in order to produce electricity. In Case 2, raw biogas is upgraded in a small-scale upgrading unit to vehicle gas standards which is sold to the market. The results show that the mixing device is promising in terms of energy use. It is therefore recommended to move on with testing of the equipment. The cover concept and the building concept show similar performance from energy and environmental standpoints. The building concept is concluded not to be economically viable. The cost reduction by applying a modular concept where one product can be used on different sized farms is significant. However, the needed investment from the company is large. The goal of achieving a modular system is therefore concluded desirable. The subsidy from the Swedish board of agriculture covering 40 % of the investment cost, has a major impact on the profitability of the systems. Without this subsidy, the systems are not viable in terms of economy. In Sweden, the small-scale vehicle gas production (Case 2) was concluded the most profitable as well as the best-performing from energy and environmental standpoints. / Inom den svenska jordbrukssektorn finns stor potential för utvidgning av biogasproduktionen. Det finns dock många problem med småskalig biogasproduktion, exempelvis olönsamma och energimässigt ineffektiva system. International Micro BioGas AB (IMB AB) har identifierat att detta till viss del kan bero på bristfälliga tekniska lösningar. Detta då det inte finns någon standardisering av teknik på området. IMB AB har, i samarbete med KTH, sedan 2014 arbetat med olika aspekter av småskalig biogasproduktion. Detta arbete undersöker ett antal innovationer och koncept från IMB AB rörande biogassystem:  En ny metod för omrörning  En byggnad som återvinner värmen från rötkamrarna (byggnadskonceptet)  Ett nytt sätt att isolera rötkamrarna (huvkonceptet)  Småskaliga och modulära paketlösningar Innovationerna och koncepten ovan utvärderas från ett energitekniskt, ekonomiskt och miljömässigt perspektiv genom en fallstudie på mjölkgården Ogestad nära Gamleby i Sverige. Två användningsområden för biogasen analyseras. I Fall 1 (Case 1) bränns rågasen i en kraftvärmeanläggning för att producera elektricitet och värme. I Fall 2 (Case 2) uppgraderas rågasen till fordonsgaskvalitet som sedan säljs till marknaden. Resultaten visar att den nya omrörningsmetoden är lovande ur ett energiperspektiv och en rekommendation är att gå vidare med tekniken och göra experimentella studier. Byggnadskonceptet och huvkonceptet visade likvärdiga resultat ur energitekniskt och miljömässigt perspektiv. Byggnadskonceptet konstaterades vara ineffektivt ur ett ekonomiskt perspektiv. Kostnadsreduceringen som uppnås genom att systemet är modulärt och därmed kan produceras i stor skala till olika gårdsstorlekar, är signifikant. Det krävs dock en stor investering från företagets sida. För samtliga fall är systemens lönsamhet starkt beroende av Jordbruksverkets subvention på 40 % av investeringskostnaden och utan den ökar företagets investeringsbehov drastiskt. Med svenska förutsättningar är småskalig produktion av fordonsgas det mest lönsamma samt mest fördelaktiga ur ett miljö- och energiperspektiv.

Pt-aluminide (PtAl) coatings form an integral part of thermal barrier coating (TBC) systems that are applied on Ni-based superalloy components operating in the hot sections of gas turbine engines. These coatings serve as a bond coat between the superalloy substrate and the ceramic yttrium stabilized zirconia (YSZ) coating in the TBC system and provide oxidation resistance to the superalloy component during service at high temperatures. The PtAl coatings are formed by the diffusion aluminizing process and form an integral part of the superalloy substrate. The microstructure of the PtAl coatings is heavily graded in composition as well as phase constitution. The matrix phase of the coating is constituted of the B2-NiAl phase. Pt, in the coating, is present as a separate PtAl2 phase as well as in solid solution in B2-NiAl. The oxidation resistance of the PtAl bond coat is derived from the B2-NiAl phase. At high temperatures, Al from the B2-NiAl phase forms a regenerative layer of alumina on the coating surface which, thereby, lowers the overall oxidation rate of the superalloy substrate. The presence of Pt is beneficial in improving the adherence of the alumina scale to the surface and thereby enhancing the oxidation resistance of the coating. However, despite its excellent oxidation resistance, the B2-NiAl being an intermetallic phase, renders the PtAl coating brittle and imparts it with a high brittle-to-ductile-transition-temperature (BDTT). The PtAl coating, therefore, remains prone to cracking during service. The penetration of these cracks into the substrate is known to degrade the strain tolerance of the components. Evaluation of the mechanical behavior of these coatings, therefore, becomes important from the point of views of scientific understanding as well as application of these coatings in gas turbine engine components. Studies on the mechanical behavior of coatings have been mostly carried on coated bulk superalloy specimens. However, since the coating is brittle and the superalloy substrate more ductile when compared to the coating, the results obtained from these studies may not be representative of the coating. Therefore, it is imperative that the mechanical behavior of the coating in stand-alone condition, i.e. the free-standing coating specimen without any substrate attached to it, be evaluated for ascertaining the true mechanical response of the coating. Study of stand-alone bond coats involves complex specimen preparation techniques and challenging testing procedures. Therefore, reports on the evaluation of mechanical properties of stand-alone coatings are limited in open literature. Further, no systematic effort has so far been made to examine important aspects such as the effect of temperature and strain rate on the tensile behavior of these coatings. The deformation mechanisms associated with these bond coats have also not been reported in the literature. In light of the above, the present research study aims at evaluating the tensile behavior of free-standing PtAl coatings by the micro-tensile testing technique. The micro-tensile testing method was chosen for property evaluation because of its inherent ability to generate uniform strain in the specimen while testing, which makes the results easy to interpret. Further, since the technique offers the feasibility to test the entire graded PtAl coating in-situ, the results remain representative of the coating. Using the above testing technique, the tensile behavior of the PtAl coating has been evaluated at various temperatures and strain rates. The effect of strain rate on the BDTT of the coating has been ascertained. Further, the effect of Pt content on the tensile behavior of these coatings has also been evaluated. Attempts have been made to identify the mechanisms associated with tensile deformation and fracture in these coatings. The thesis is divided into nine chapters. Chapter 1 presents a brief introduction on the operating environment in gas turbine engines and the materials that are used in the hot sections of gas turbine engines. The degradation mechanisms taking place in the superalloy in gas turbine environments and the need for application of coatings has also been highlighted. The basic architecture of a typical thermal barrier coating (TBC) system applied on gas turbine engine components has been presented. The constituents of the TBC system, i.e. the ceramic YSZ coating, MCrAlY overlay as well as diffusion aluminide bond coats and, the various techniques adopted for the deposition of these coatings have been described in brief. Chapter 2 presents an overview of the literature relevant to this study. This chapter is divided into four sub-chapters. The formation of diffusion aluminide coatings on Ni-based superalloys has been described in the first sub-chapter. Emphasis has been laid on pack cementation process for the formation of the coatings. The fundamentals of pack aluminizing process, including the thermodynamic and kinetic aspects, have been mentioned in brief. The microstructural aspects of high activity and low activity plain aluminide and Pt-aluminide coatings have also been illustrated. The techniques applied for the mechanical testing of bond coats have been discussed in the second sub-chapter. The macro-scale testing techniques have been mentioned in brief. The small scale testing methods such as indentation, bend tests and micro-tensile testing have also been discussed in the context of evaluation of mechanical properties of bond coats. Since the matrix in the aluminide bond coats is constituted of the B2-NiAl phase, a description of the crystal structure and deformation characteristics of this phase including the flow behavior, ductility and fracture behavior has been mentioned in the third sub-chapter. In the fourth sub-chapter, reported literature on the tensile behavior and brittle-to-ductile-transition-temperature (BDTT) of diffusion aluminide bond coats has been discussed. In Chapter 3, details on experiments carried out for the formation of various coatings used in the present study and, their microstructural characterization, are provided. The method for extraction of stand-alone coating specimens and their testing is discussed. The microstructure and composition of the various coatings used in the present study are discussed in detail in Chapter 4. Unlike in case of bulk tensile testing, for which standards on the design of specimens exist, there are no standards available for the design of micro-tensile specimens. Therefore, as part of the present research work, a finite element method (FEM)-based study was carried out for ascertaining the dimensions of the specimens. The simulation studies predicted that failure of the specimens within the gage length can be ensured only when certain correlations between the dimensional parameters are satisfied. Further, the predictions from the simulation study were validated experimentally by carrying out actual testing of specimens of various dimensions. Details on the above mentioned aspects of specimen design are provided in Chapter 5. The PtAl coatings undergo brittle fracture at lower temperatures while ductile fracture occurs at higher temperatures. Further, the coatings exhibit a scatter in the yielding behavior at temperatures in the vicinity of BDTT. Therefore, the BDTT, determined as the temperature at which yielding is first observed in the stress-strain curves, may not be representative of the PtAl coatings. In Chapter 6, a method for the precise determination of BDTT of aluminide bond coats, based on the variation in the plastic strain to fracture with temperature, has been demonstrated. The BDTT determined by the above method correlated well with the variation in fracture surface features of the coating and was found representative of these coatings. In Chapter 7, the effect of temperature and strain rate on the tensile properties of a PtAl bond coat has been evaluated. The temperature and strain rate was varied between room temperature (RT)-1100°C and 10-5 s-1-10-1 s-1, respectively. The effect of strain rate on the BDTT of the PtAl bond coat has been examined. Further, the variation in fracture surface features and mechanism of fracture with temperature and strain rate are illustrated. The micro-mechanisms of deformation and fracture in the coating at different temperature regimes have also been discussed. The coating exhibited brittle-to-ductile transition with increase in temperature at all strain rates. The BDTT was strain rate sensitive and increased significantly at higher strain rates. Above BDTT, YS and UTS of the coating decreased and its ductility increased with increase in the test temperature at all strain rates. Brittle behavior occurring in the coating at temperatures below the BDTT has been attributed to the lack of operative slip systems in the B2-NiAl phase of the coating. The onset of ductility in the coating in the vicinity of BDTT has been ascribed to generation of additional slip systems caused by climb of dislocations onto high index planes. The coating exhibited two distinct mechanisms for plastic deformation as the temperature was increased from BDTT to 1100°C. For temperatures in the range BDTT to about 100°C above it, deformation was controlled by dislocations overcoming the Peierls-Nabarro barrier. Above this temperature range, non-conservative motion of jogs by jog dragging mechanism controlled the deformation. The transition temperature for change of deformation mechanism also increased with increase in strain rate. For all strain rates, fracture in the coating at test temperatures below the BDTT, occurred by initiation of cracks in the intermediate single phase B2-NiAl layer of the coating and subsequent inside-out propagation of the cracks across the coating thickness. Ductile fracture in the coating above the BDTT was associated with micro-void formation throughout the coating. The effect of Pt content on the tensile behavior of PtAl coating, evaluated at various temperatures ranging from room temperature (RT) to 1100°C and at a nominal strain rate of 10-3 s-1, is presented in Chapter 8. Irrespective of Pt content in the coating, the variation in tensile behavior of the coating with temperature remained similar. At temperatures below BDTT, the coatings exhibited linear stress-strain response (brittle behavior) while yielding (ductile behavior) was observed at temperatures above BDTT. At any given temperature, the elastic modulus decreased while the strength increased with increase in Pt content in the coating. On the other hand, the ductility of the coating remained unaffected with Pt content. The BDTT of the coating also increased with increase in Pt content in the coating. Addition of Pt did not affect the fracture mechanism in the coating. Fracture at temperatures below BDTT was caused by nucleation of cracks at the intermediate layer and their subsequent inside-out propagation. At high temperatures, fracture occurred in a ductile manner comprising void formation, void linkage and subsequent joining with cracks. The deformation sub-structure of the coating did not get affected with Pt incorporation. Short straight dislocations were observed at temperatures below BDTT, while, curved dislocations marked by jog formation were observed at temperatures above BDTT. The factors controlling fracture stress and strength in the PtAl coatings at various temperatures have also been assessed. The overall summary of the present research study and recommendations for future studies are presented in the last chapter, i.e. Chapter 9.

本研究的內容，主要是以居住在大台北地區20歲以上之就業者為研究對象，藉著問卷調查的方式，從需求面來探討消費者對重大疾病保險的看法與期許。分析方法分別為次數分配、因素分析、Cronbach α、單因子變異數分析、交叉分析。 本研究將保險購買評估準則，利用因素分析將之區分為「公司狀況與產品利益」、「過去與週遭經驗」、「保費及公司型態」、「感情與服務態度」及「專業能力」等五個因素。並探討各因素在購買經驗及人口統計變數上是否具顯著差異。另外分別針對購買和理賠經驗、購買動機、購買意願、資訊來源、人口統計變數與產品利益屬性等方面做卡方（χ2）獨立性檢定。研究發現： 1.就保險購買評估準則方面： 最受重視的是「公司狀況與產品利益」，其次則為「過去與週遭經驗」，而最不受重視的則為「保費及公司型態」。 2. 購買重大疾病保險之經驗、原因與資訊管道 （1）受訪者中投保重大疾病保險的比例有六成以上，整體而言，已婚者購買的比例大於未婚者；而隨著收入的增加其購買重大疾病保險的比例也增加。 （2）未購買及中斷購買原因主要是「保費負擔太重」、「對保障內容不滿意或不瞭解」以及「已有全民健保就足夠」。 （3）購買資訊管道以「保險業務人員的推銷」、「親友的介紹」以及「公司的團體保險」為主。 3. 產品利益屬性 （1）對於重大疾病保險未來發展方向的選擇，以「增加重大疾病的項目」、「結合其他醫療功能的保單」以及「增加給付方式的選擇」等三項為大部分受訪者的選擇。 （2）保險金給付的偏好方式，以一次金給付、分次終身給付及代付醫療費用三者之接受度最高。 （3）適當的重大疾病給付額度，大多數的受訪者認為應在101∼300萬之間。 / This study focus on labor people aged from 20 in metropolitan Taipei arena. By questionnaire interviews, we will study the customers' opinions and expectations to dread disease insurances from market demand. The analytical methods will be described as followings: Frequency Distribution, Factor Analysis, Cronbach α, One-Way Anova Analysis and Crosstable. The study classifies the purchasing evaluation criteria of insurance as five factors such as “Cooperation situation and product profit margin”, “Past and surrounding experiences”, “Insurance premium and cooperate types”, “Emotion and service attitudes” and “Professional”. And explores the possibilities of the apparent differences for each factor to purchasing experiences and demographic variables. On the other hand; we try to make χ2 independence evaluation to purchasing & reimbursement experiences, purchasing motivation, purchasing intention, information resources, demographic variables and product profit properties. We found: 1.The evaluation criteria of buying insurance: People more emphasize on “Cooperation situation and product profit margin” and followings by “Past and surrounding experiences”. And less emphasis on “Insurance premium and cooperate types” 2.The experiences, results and information channels for purchasing serious disease suffered insurance: (1)The proportion of holding policy for serious disease is 60% or above. Generally speaking, the proportion of married people policyholder is larger that the one of single people. And the more the income increases;the more the proportion of purchasing disease suffered insurance increases. (2)The main reasons of not purchasing or quitting are “Premiums are too expensive”, “Not really satisfy or understand the contents of insurance covered”, and “It’s quite enough for having public healthy insurance”. (3)The main information channels to purchase insurances are “The promotion of insurance sales people”, “Relatives & friends introduction”, and “Cooperation group insurance”. 3.Product profit properties: (1)For the options of dread disease insurance development, generally, there would be three items to be acceptable such as “Additional benefits of dread diseases”, “Combine with policies of other medical functions”, and “Additional options of payment mode”. (2)The preferred payment way of premiums will be “Pay off”, “Life Amortization ”, and “Pay medical expenses by agent” and more acceptable. (3)Most interviewees think that the reasonable benefit amount for dread disease insurance will target on between NT$1 million and NT$3 million.

Η διπλωματική εργασία που ακολουθεί, παρουσιάζει τη μελέτη και μοντελοποιήση ενός αυτόνομου υβριδικού συστήματος. Το αυτόνομο σύστημα που εξετάζεται είναι ένα υβριδικό σύστημα ηλεκτροπαραγωγής που αποτελείται από ένα φωτοβολταϊκό πάρκο, μία ανεμογεννήτρια, μία μονάδα υδρογόνου και δύο γεννήτριες βιομάζας και φυσικού αερίου. Για την μοντελοποίηση του συστήματος χρησιμοποιείται το πρόγραμμα σχεδιάσης και προσομοίωσης ηλεκτρικών συστημάτων PSCAD. Στην εργασία αυτή το ενδιαφέρον εστιάζεται στη συμπεριφορά του συστήματος στη μόνιμη κατάσταση λειτουργίας και στη συμπεριφορά σε κάποια μεταβατικά φαινόμενα. Τα μεταβατικά φαινόμενα που εξετάζονται είναι τα εξής: - Βραχυκύκλωμα των τριών φάσεων ως προς γη στο ζυγό της σύγχρονης γεννήτριας φυσικού αερίου - Συμπεριφορά συστήματος σε απότομη αποσύνδεση της ανεμογεννήτριας - Συμπεριφορά συστήματος σε διακοπή παροχής ρεύματος στην μονάδα υδρογόνου από το Φ/Β πάρκο Στο Κεφάλαιο 1 γίνεται μία γενικότερη αναφορά στο Φ/Β σύστημα. Στο Κεφαλαιο 2 γίνεται μία γενικότερη αναφορά στην αιολική ενέργεια. Στο Κεφάλαιο 3 γίνεται μία γενικότερη αναφορά στο υδρογόνο. Στο Κεφάλαιο 4 γίνεται μία γενικότερη αναφορά στην βιομάζα. Στο Κεφάλαιο 5 γίνεται μία γενικότερη αναφορά στο φυσικό αέριο. Στο Κεφάλαιο 6 γίνεται μία γενικότερη αναφορά στις σύγχρονες μηχανές και στο μαθηματικό τους υπόβαθρο. Στο Κεφάλαιο 7 περιγράφεται η δομή και τα στοιχεία που αποτελούν το αυτόνομο υβριδικό δίκτυο ηλεκτροπαραγωγής στο περιβάλλον του προγράμμματος μοντελοποιήσης, του PSCAD και παρουσιάζονται τα μοντέλα που απαρτίζουν το συνολικό σύστημα. Στο Κεφάλαιο 8 εξετάζεται η συμπεριφορά του συστήματος στη μόνιμη κατάσταση λειτουργίας. Στο Κεφάλαιο 9 εξετάζεται η συμπεριφορά του συστήματος στα τρία μεταβατικά φαινόμενα που έχουν προαναφερθεί, στο βραχυκύκλωμα των τριών φάσεων ως προς γη στο ζυγό της σύγχρονης γεννήτριας φυσικού αερίου, στην απότομη αποσύνδεση της ανεμογεννήτριας και στην διακόπη παροχής ρεύματος στην μονάδα υδρογόνου. / The thesis that follows, presents the study and the modelling of an autonomous hybrid system. The autonomous system that is examined is an electricity generating hybrid system that constists of a photovoltaic system, a wind generator, a hydrogen unit, a biomass generator and a natural gas generator. For the modelling of the system a designing and simulation program is used known as PSCAD. The main course of the current subject is the behavior of the system in the permanent situation of operation and the behavior of it in certain transient states. The transient states that are examined are the following: - Short-circuit of the three phases as for the ground on the natural gas generator bus. - Behavior of system in abrupt detachment of wind generator. - Behavior of system in abrupt detachment of the hydrogen unit. In Chapter 1 follows a theoretical analysis of the PV system. In Chapter 2 follows a theoretical analysis of the wind generator. In Chapter 3 follows a theoretical analysis of the hydrogen unit. In Chapter 4 follows a theoretical analysis of the biomass. In Chapter 5 follows a theoretical analysis of the natural gas. In Chapter 6 follows a theoretical and mathematical analysis of the synchronous machines. In Chapter 7 we describe the structure and the elements that constitute the autonomous hybrid system of electric generation in the environment of PSCAD. Also, the models that compose the total system are shown. In Chapter 8 is examined the reaction of system in the permanent situation of operation. In Chapter 9 is examined the reaction of system in the three transient states that have been mentioned before.