Plasmonic properties of self-assembled silver nanoparticles/nanowires array on periodically patterned Si (100) substrate are reported with special attention on the mechanism of nanoparticles self-assembly. The advantage of this bottom up approach over other self-assembling and lithographic methods is the flexibility to tune array periodicity down to 20 nm with interparticle gaps as low as 5 nm along the ripple. Ripple pattern have shallow modulation (~2 nm) still particles self-assembly was observed in non-shadow deposition. Therefore adatoms diffusion and kinetics is important on ripple surface for the self-assembly. PVD e-beam evaporation method used for deposition has proven to be superior to sputter deposition due to lower incident flux and lower atom energy. It was found that particles self-assembly largely dependent on angle of incidence, substrate temperature, and deposition direction due to ripple asymmetric tilt. Ostwald ripening observed during annealing on ripples substrate has striking dependency on ripple periodicity and was found to be different compared to Ostwald ripening on flat Si surface. In-situ RBS measurements of deposited silver on flat and rippled substrate confirmed different sticking of atoms on the two surfaces. The difference between maximum and minimum of the calculated local flux show a peak at an incidence angle of 70o with respect to surface normal. This explains the best alignment of particles at this angle of incidence compare to others. Self-assembled nanoparticles are optically anisotropic, i.e. they exhibit a direction dependent shift in LSPR. The reason of the observed anisotropy is a direction dependent plasmonic coupling. Different in plane and out of the plane dielectric coefficients calculated by modelling Jones matrix elements, confirms that nanoparticle/nanowire array are biaxial anisotropic (ex ¹ ey ¹ ez). The nanoparticles are predominantlyinsulating while nanowires are both metallic and insulating depending on the dimension. Silver nanoparticles/nanowires self-aligned on pre-patterned rippled substrate are presented for the first time as an active SERS substrate. Anisotropic SERS response in such arrays is attributed to different field enhancement along and across the ripples. Strong plasmonic coupling in elongated nanoparticles chain results in significantly higher SERS intensity then spherical nanoparticles/nanowires and non-ordered nanoparticles. Higher SERS intensity across the nanowires array in comparison to along the array (bulk silver) confirms electromagnetic field enhancement (hot-junction) is responsible for SERS phenomenon. Self-assembly of cobalt nanoparticle on ripple pattern substrate is also reported. Due to less adatom mobility and higher sticking cobalt self-assembly is possible only at much higher temperature. A strong uniaxial magnetic anisotropy was observed not observed for non ordered cobalt particles.

<p>As a cost-effective, healthy, and environmentally friendly personal mode of transportation, electric bicycles (E-bikes) are gaining an increasing market share from conventional bicycles and automobiles. Considering the legal rules in Ontario, Canada, a 500W motor makes the E-bike more attractive for travelling use. At the same time, the simple structure, high torque and power density, as well as the low cost of the switched reluctance machine (SRM) makes it a strong candidate for E-bikes.</p> <p>In this thesis, a 3-phase, external-rotor SRM with 6 stator poles and 10 rotor poles is designed for E-bike. The design of an external rotor arrangement of the 6-10 SRM topology has not previously been reported, hence it offers a new contribution to the published works. The machine design is initiated by the output power equation and is followed by a comprehensive finite element analysis (FEA). The external-rotor arrangement is chosen to facilitate ease of integration into the wheel hub structure of a typical pedal bicycle. The increasing rotor poles yield improved torque ripple reduction than more conventional (i.e. 6-4, 12-8 etc.) SRM design, which is an essential feature for low speed rider comfort.</p> <p>A new torque ripple reduction control scheme is investigated. Although the comparison shows that the torque sharing function has more positive result than angular position control with regards to torque ripple, this is at the expense of higher losses. Detailed thermal analysis ensures this machine is suitable to require no additional cooling system. The final machine design is experimentally tested via a full system prototype. Results highlight some limitation of the 2-D FEA in terms of the winding inductance calculation. Here, the end winding introduce more influence on short thickness machine, which will reduce its output power. However, its power-speed curve shows that this prototype machine has very strong overload ability.</p> / Master of Applied Science (MASc)

This thesis proposes novel methods and comprehensive analysis for power loss calculation, DC-link current and voltage ripple estimation, and bus bar design in two-level three-phase voltage source inverters (VSIs). A novel method of MOSFET voltage rise- and fall-time estimations for the switching power loss calculation is developed. The estimation accuracy is significantly improved by the proposed method. In order to provide a reference for thermal management design, inverter power loss analysis is presented. Using the parameters obtained from the semiconductor device datasheets and inverter operating conditions, power loss calculations of three types of devices, namely IGBT, MOSFET, and diode, are discussed. The conduction power loss calculations for these three devices are straightforward; and, the switching power loss of IGBTs and diodes can be obtained from the energy losses given by datasheets. However, many MOSFET datasheets do not provide the switching energy losses directly. Therefore, to acquire MOSFET switching energy losses, switching transient times must be estimated as accurately as possible. The impacts of inverter anti-parallel diode reverse recovery on the DC-link current and voltage ripples are investigated. According to the analysis, the impact of diode reverse recovery on the voltage ripple is negligible, while the RMS value of current ripple is influenced by both diode reverse recovery and inverter switching frequency. A novel method is developed to calculate the ripple current RMS value and the estimation accuracy is significantly improved. Depending on the calculated current and voltage ripples, DC-link capacitor selection is introduced. Generally speaking, failures in the DC-link capacitors take place more frequently than the failures in other parts of the inverter system, and plenty of research has been focusing on minimizing the required DC-link capacitance. As a result, the accurate estimations of DC-link current and voltage ripples are vital in the optimization methods. In addition, with the accurate estimations, the over-design in the DC-link capacitance could be reduced. Finally, the design of a practical bus bar is presented. The DC current distribution is aff ected by the numbers and locations of the DC input tabs, while the AC current distribution is influenced by the numbers and locations of the installation holes for DC-link capacitors and semiconductor devices. Furthermore, parasitic parameters of the bus bar, especially the stray inductance and voltage spikes caused by this inductance during switching turn-o transients, are also discussed from the angle of the design rules and correlation between the parameters and bus bar geometry structure. In the end, a bus bar is designed with balanced current distribution and low stray inductance. / Thesis / Doctor of Philosophy (PhD)

The continual development of high-power-density power electronic converters is driven particularly by modern transportation applications like electrical vehicles and more electric aircraft where the space and carrier capability is limited. However, there are several challenges related to transportation applications such as fault tolerance for safety concern, high temperature operation in extreme environments and more strict electromagnetic compatibility requirement. These challenges will increase difficulties for more electrical system adoption in the transportation applications. In this dissertation, comprehensive methodologies including more efficient energy storage solution, better power electronics devices capability, better packaging performance and more compact EMI filter design are analyzed and proposed for the goal of high power density converter design in transportation applications. / Ph. D.

In Quality Management and Total Quality Management (TQM) customer focus and customer value creation is of importance and in organisations it is of high priority. Quality Management has had an internal focus when it comes to customer value creation but in the 21st century there is a need for an outward orientation and to go beyond the organisational borders. Also an increasing interest in social, societal and environmental issues can be seen, for instance by customers, organisations, quality awards and within the quality area. An area that considers these issues is the societal entrepreneurial sector.   The purpose of this thesis has been to contribute to the knowledge and understanding about customer value creation from a system view. Additionally the purpose has been to contribute to the development of Quality Management. In order to fulfil the purpose, case studies have been performed. Cases within the societal entrepreneurial area have been studied and seven studies have been performed. Data have been collected through interviews, direct observations, participating observations and documents. All data have been collected empirically except in one study where a literature case study was used. The data were analysed through tools such as process mapping, attribute value mapping and rich picture process maps combined with analytical methods for case study research. The research journey started out from TQM and an internal perspective on customer value creation. As the studies went on, the system borders became wider as other areas important to customer value creation were identified: the customer value creating system went from an internal perspective to include an external perspective.    The findings contribute to earlier research findings and give a comprehensive and simplified picture of a complex phenomenon and an opportunity to understand customer value creation from a system view. This thesis provides an overall map of the customer value creating system. Additionally it contributes to the development of Quality Management by expanding the view on customer value creation to include both an internal and an external oriented perspective. It also contributes by suggesting a fifth step in the quality management movement ´System Quality Management´ that considers social, societal and environmental factors through continuous improvement before, during and after value creation for customers. Further it contributes with a developed view on customers and the concept of customer value creation.   The overall map provided includes three areas. Growth and development of societal entrepreneurial initiatives. The result shows important components for the creation of societal value based on the growth and development of societal entrepreneurial initiatives. Included are the processes, input and output important for societal value creation from unidentified needs until societal value can be delivered, management process and support process fields.  Customer value creation in the customer sphere.  Customer value has been found to be created beyond the use or purchase of a product or service. Value has also been found to be created for those that are not in direct contact with an initiative or its product or service. Customer value has been found to spread into society like ripples in a complex system of value creation. And Value Ripple Logic has been developed to describe this phenomenon. Management role in customer value creation. The management’s role in value creation has been found to be of importance in the creation of customer value in an indirect way through interaction with the surroundings and the initiative.  Factors and behaviours have been found which are connected to the leaders and their essential management processes along with their input and output.   The findings presented in this thesis have considerable potential for development. Further studies need to be done within the area concerning how customer value is created and to achieve an even more comprehensive picture of the customer value creating system and the suggested fifth step. The results presented in this thesis are a contribution to the knowledge and understanding about customer value creation from a system view and the development of the Quality Management. / <p>Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 6 accepterat för publicering och delarbete 7 inskickat.</p><p>At the time of the doctoral defence the following papers were unpublished: paper 6 accepted for publication and  paper 7 submitted.</p>

The aviation environment holds challenging application constraints for efficient hydraulic system noise reduction devices. Besides strong limits on component weight and size, high safety and reliability standards demand simple solutions. Hence, basic silencers like inline expansion chambers and Helmholtz-Resonators are state-of-the-art aboard commercial aircrafts. Unfortunately, they do not meet today’s noise attenuation aims regarding passenger comfort and equipment durability. Significant attenuation performance is expected from active concepts that generate anti-phase noise. However, such concepts remain a long term approach unless related costs, e.g. due to additional power allocation and real-time control equipment can be avoided. In this paper an active fluid borne noise attenuation concept is discussed that accounts for the mentioned constraints. An aircraft hydraulic pump is considered as main noise source. The active attenuator is an in-house rotary valve design. The basic feature is a known direct shaft coupling principle of pump and rotary valve, so no speed/ frequency control of the valve and no separate power supply are required. The common-shaft principle is further simplified here and proposed as integral feature of future “smart pumps”.

A finalidade inicial deste estudo foi desenvolver um modelo computacional multifísico de um acionamento eletrônico, composto por um motor de relutância 4/2 bifásico, um conversor eletrônico de potência, um controlador, os componentes mecânicos estruturais do motor e os acoplamentos entre os diferentes domínios físicos. Para a implementação do modelo proposto, foram utilizados recursos de simulações numéricas e acopladas do MEF (Método dos Elementos Finitos) em uma plataforma de simulação multifísica, de modo a realizar acoplamento entre três áreas do conhecimento: circuitos elétricos, campos eletromagnéticos e componentes mecânicos estruturais e de vibração. Uma vez desenvolvido o modelo multifísico, este foi associado a um procedimento de otimização dos ângulos de disparo que utiliza um modelo de algoritmos genéticos e, como um conjunto, estes foram aplicados na redução da vibração e da ondulação de torque do motor de relutância chaveado, resultando em uma nova metodologia para a abordagem desses problemas. De modo a comprovar os resultados obtidos nas simulações, foram realizados diversos ensaios experimentais para a validação de cada etapa do desenvolvimento, tais como levantamento das formas de onda de tensão e correntes, ensaios de vibração, etc. Os modelos desenvolvidos foram testados em função de modificações realizadas tanto nos parâmetros de controle do acionamento, como também em função de modificações mecânicas estruturais na geometria do rotor. / The initial purpose of this study was developing a multi-physical computational model of a power electronic motor drive, composed to a 2-Phase Switched Reluctance Motor (SRM) 4/2, a power electronic converter, a controller, motor mechanical and structural components and the coupling among different physical domains. For implementing of the proposed model, it was used FEM (Finite Element Method) coupled and numerical simulations resources in a multi-physic simulation platform, in order to accomplish the coupling among the three areas of knowledge: electrical circuits, electromagnetic fields and structural and mechanics components and vibration. Once finished the multi-physical model, it was associated with a optimization procedure of firing angles which uses genetic algorithm model and, as a whole, it was applied on the SRM vibration and torque ripple reduction, resulting in a new methodology to approaching these problems. In order to prove obtained simulation results, it was carried out several experimental tests to validate each development stage, such as the voltage and currents wave forms mapping, vibration tests, etc. The developed models were tested as much function of drive control parameters as the rotor geometry mechanical and structural modifications.

A finalidade inicial deste estudo foi desenvolver um modelo computacional multifísico de um acionamento eletrônico, composto por um motor de relutância 4/2 bifásico, um conversor eletrônico de potência, um controlador, os componentes mecânicos estruturais do motor e os acoplamentos entre os diferentes domínios físicos. Para a implementação do modelo proposto, foram utilizados recursos de simulações numéricas e acopladas do MEF (Método dos Elementos Finitos) em uma plataforma de simulação multifísica, de modo a realizar acoplamento entre três áreas do conhecimento: circuitos elétricos, campos eletromagnéticos e componentes mecânicos estruturais e de vibração. Uma vez desenvolvido o modelo multifísico, este foi associado a um procedimento de otimização dos ângulos de disparo que utiliza um modelo de algoritmos genéticos e, como um conjunto, estes foram aplicados na redução da vibração e da ondulação de torque do motor de relutância chaveado, resultando em uma nova metodologia para a abordagem desses problemas. De modo a comprovar os resultados obtidos nas simulações, foram realizados diversos ensaios experimentais para a validação de cada etapa do desenvolvimento, tais como levantamento das formas de onda de tensão e correntes, ensaios de vibração, etc. Os modelos desenvolvidos foram testados em função de modificações realizadas tanto nos parâmetros de controle do acionamento, como também em função de modificações mecânicas estruturais na geometria do rotor. / The initial purpose of this study was developing a multi-physical computational model of a power electronic motor drive, composed to a 2-Phase Switched Reluctance Motor (SRM) 4/2, a power electronic converter, a controller, motor mechanical and structural components and the coupling among different physical domains. For implementing of the proposed model, it was used FEM (Finite Element Method) coupled and numerical simulations resources in a multi-physic simulation platform, in order to accomplish the coupling among the three areas of knowledge: electrical circuits, electromagnetic fields and structural and mechanics components and vibration. Once finished the multi-physical model, it was associated with a optimization procedure of firing angles which uses genetic algorithm model and, as a whole, it was applied on the SRM vibration and torque ripple reduction, resulting in a new methodology to approaching these problems. In order to prove obtained simulation results, it was carried out several experimental tests to validate each development stage, such as the voltage and currents wave forms mapping, vibration tests, etc. The developed models were tested as much function of drive control parameters as the rotor geometry mechanical and structural modifications.

Submitted by PPG Engenharia El?trica (engenharia.pg.eletrica@pucrs.br) on 2018-10-31T13:57:50Z No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-11-01T11:50:43Z (GMT) No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) / Made available in DSpace on 2018-11-01T12:00:28Z (GMT). No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) Previous issue date: 2018-08-31 / Power converters are widely used in the context of power electronics. In the same way that transformers have a fundamental role in applications involving AC circuits, power converters modify voltage magnitudes in DC circuits. These devices can either present an output voltage higher than the input voltage, acting as a Boost converter, or lower, acting, in this case, as a Buck converter. The input and output signals can also present either a voltage source or a current source behavior, depending on the topology. This work presents a systematic study of the D converter operating in the continuous conduction mode, in permanent regime, including the qualitative and quantitative analyzes, resulting in a methodology of dimensioning of the converter, as well as its modeling in space of states, which makes feasible studies of control strategies for it. Although this is not a new topology, this converter has recently been reintroduced due to its ability to increase efficiency in the energy conversion process, especially in photovoltaic systems. However, this research is fully justified given the lack of similar work for the D converter topology. This study was validated from tests performed in the PSIM simulation software, in addition to MATLAB / SIMULINK. A laboratory prototype was specially constructed for validation purposes in a rapid prototyping platform, as well as the consequent implementation in a PCI, for use in future works. / Os conversores est?ticos s?o amplamente utilizados no contexto da eletr?nica de pot?ncia. Da mesma forma que os transformadores t?m papel fundamental nas aplica??es que envolvem circuitos alimentados em corrente alternada, os conversores est?ticos realizam a transforma??o de magnitudes de tens?o em circuitos de corrente cont?nua. Tais dispositivos podem tanto apresentar em sua sa?da um valor de tens?o superior em rela??o ao sinal de entrada, atuando como elevadores, quanto inferior, atuando, neste caso, como redutores. Estes tamb?m podem apresentar suas sa?das ou entradas com um comportamento de fonte de tens?o ou corrente, dependendo da topologia utilizada. Este trabalho apresenta um estudo sistematizado do conversor D operando no modo de condu??o cont?nua, em regime permanente, incluindo as an?lises qualitativa e quantitativa, resultando em uma metodologia de dimensionamento do conversor, bem como a sua modelagem em espa?o de estados, o que viabiliza estudos de estrat?gias de controle para o mesmo. Apesar de n?o se tratar de uma nova topologia, recentemente este conversor foi reintroduzido, devido a sua capacidade de aumentar a efici?ncia no processo de convers?o de energia, especialmente em sistemas fotovoltaicos. Esta pesquisa encontra justificativa dada a inexist?ncia de trabalhos semelhantes especificamente para a topologia do conversor D. Este estudo foi validado a partir de ensaios realizados no software de simula??o PSIM, al?m do MATLAB/SIMULINK. Um prot?tipo de laborat?rio foi especialmente constru?do para fins de valida??o em uma plataforma de prototipagem r?pida, bem como a consequente implementa??o do mesmo em uma PCI, para utiliza??o em trabalhos futuros.

With the invention of the cryptocurrency Bitcoin in 2009, the world's first blockchain application was developed. While academic research gradually begins to investigate cryptocurrencies more closely and attempt to understand their functioning, technology is rapidly evolving and ecosystems grow exponentially. The research is still scattered and chaotic and has not produced common guidelines. Therefore, the question remains: how sustainable cryptocurrencies and their digital ecosystems are.Only a few models and frameworks take a holistic view on digital sustainability. Only two frameworks were identified that take distributed ledger technologies (blockchain) or cryptocurrencies into consideration: the three governance strategies for digital sustainability of Linkov et al. (2018) and 10 basic conditions of sustainable digital artifacts according to Stuermer, Abu-Tayeh and Myrach (2016). These two frameworks were combined into a new integrated sustainability framework for cryptocurrencies. The developed integrated sustainability framework consists of four dimensions and 12 categories.Existing secondary data, self-conducted social media interviews and practical insights gained through an ASIC mining experiment were used to fill the framework with sufficient data. It confirms Bitcoin's sustainability problems in energy consumption and scalability, highlights Ethereum's great potential as a blockchain platform and explains the higher scalability and faster payment of Ripple and IOTA.While 2017 marked the temporary peak of the cryptocurrency hype, 2018 was a transformative year in which the leading cryptocurrencies were increasingly occupying more specialised niches.