In this work, the doping processes of the SA type stepped Ge (100) surface by arsine (AsH3) and diborane (B2H6) gas flow have been simulated seperately by the possible adsorption and dissociation models. The most stable adsorption and dissociation models of AsH3 and B2H6 on stepped Ge(100) surface have been determined by the local minimum total energy and/or binding energy calculations based on Hartree-Fock Theory. The present calculations have shown that, the step region (both up and down terraces) of the stepped Ge (100) surface has the most attractive sites for the initial adsorption stages of the gas molecules. It has been found that the thermodynamically preferred structures in the dissociation paths of arsine and diborane are the same / AsH3 , BH3 (fragment of diborane), AsH2 and BH2 products prefer to be bounded to a single surface Ge atom, but AsH and BH prefer to be bridged between two adjacent surface Ge atoms. It has been also found that, at the first step of the adsorptions, AsH3 can only dissociate to AsH2, but BH3 can dissociate to both BH2 and BH. This remarkable result has showed that dissociation of BH3 on Ge(100) surface can be easier than AsH3&rsquo / s. According to the optimization calculations, the dissociation path has started with the adsorption of AsH3 (or BH3) on the electron deficient side (buckled down) of the Ge dimer bond and ended with the occupation of the empty Ge sites in the surface layers by As (or B) atom substitutionally. In the present work, the beginning of the n &ndash / (or p-) type doping of the stepped Ge(100) surface has been illustrated by the As (or B) electronic states obtained in the optical energy gap of Ge very close to HOMO (or LUMO) energy edge.

Stepped cascades are recognised for both aeration potential and energy dissipation, and have been employed in hydraulic structures for over 3,500 years. Yet little detailed information exists on their performance, especially pertaining to low-gradient cascades. This study presents a detailed investigation of both the macro and micro-scale flow properties on a low-gradient cascade (3.4º slope). Research is conducted on two large-size physical models: a 24m long multi-step cascade (10× 2.4m long steps), and a single-step model with identical step height and length. The large size of the model allows near full-scale data acquisition under controlled flow conditions, minimising potential scale effects. The study comprises three distinct components: 1. A global investigation of the general flow properties of nappe flow on a low-gradient, multi-step cascade. Unforeseen three-dimensional characteristics of the flow, including supercritical shockwaves and sidewall standing-waves downstream of nappe impact, are identified and examined by the study. Although comparable to similar phenomena at channel bends and expansions, these have not been previously described on stepped cascades. Energy dissipation on the cascade is investigated, and is found to be over twice that observed for a smooth chute of similar gradient. 2. A complete characterisation of the air-water structure of flow in a nappe regime. Significant outcomes of the analysis include: ⊕ Air-concentration Distribution: The air-concentration distribution at the lower nappe of the free-falling jet shows good agreement with an analytical solution of the diffusion equation. The experimental results from the study, and a reanalysis of existing data, indicate a distinct relationship between the turbulent diffusivity in the shear layer and distance from the step brink. This contradicts earlier investigations that assumed constant diffusivity. Strong aeration of the flow, with a large volume of spray, occurs downstream of the nappe impact. Depth-averaged air concentrations of 40% to 50% are observed within the spray region, decreasing towards the downstream end of the step. ⊕ Velocity Distribution: A theoretical analysis of the momentum transfer process imparts an improved understanding of the momentum transfer and velocity redistribution within the free-falling jet. An analytical solution based on twodimensional wake flow is developed, superseding existing solutions based upon a monophase free-mixing layer. ⊕ Bubble-frequency Distribution: A quasi-parabolic relationship between bubble frequency and time-average air concentration across a cross-section is observed. A theoretical explanation for the parabolic relationship is developed, and two correction factors are introduced to provide a better representation of the experimental data. ⊕ Air-bubble and Water-droplet Size Distributions: Chord-length distributions are compared with standard probability distributions, showing good agreement with standard Weibull, gamma and log-normal probability distributions within various regions of the flow on the step. A computer model is developed to model interaction between a bubbly transition from water to air and fluctuations of the free surface. 3. A parallel investigation of the oxygen aeration efficiency of a stepped cascade. Measured air-water property data is used to calculate the air-water interface area in bubbly flow, and to estimate the theoretical aeration efficiency of the stepped cascade based upon the integration of the mass transfer equation. The aeration performance of the stepped cascade model is also measured experimentally in terms of dissolved oxygen content. This analysis allows a unique, successful comparison of experimental dissolved oxygen measurements with the numerical integration of the mass transfer equation.

Vertedouros em degraus têm se tornado uma boa opção em barragens pela facilidade de construção e, principalmente, por apresentar uma dissipação significativa de energia ao longo de sua calha, o que faz com que a parcela de energia a ser dissipada por ressalto hidráulico a jusante da barragem diminua, ocasionando uma significativa redução nas dimensões da estrutura da bacia de dissipação. A aplicação de soleira terminal em bacias de dissipação provoca uma melhor distribuição das velocidades e um melhor comportamento da flutuação de pressões ao longo da bacia e a jusante, aumentando assim seu desempenho na dissipação de energia. A combinação destas duas formas de dissipação (vertedouro em degraus e bacia de dissipação com soleira terminal) pode ser utilizada como uma solução econômica e segura, entretanto, o dimensionamento dessas estruturas esbarra na falta de critérios e informações, principalmente quanto ao tamanho e posição ideal para o projeto de uma soleira terminal. No presente trabalho foram analisados os dados de pressões médias e flutuações de pressões no interior da bacia e a jusante da soleira terminal, sendo apresentadas metodologias para dimensionamento de tamanho e para posicionamento de uma soleira em função do número de Froude da entrada do ressalto hidráulico. Também está sendo apresentada uma metodologia para análise das pressões médias em bacia do tipo I (sem soleira), além de uma comparação do comportamento dos esforços em bacia com soleira e sem soleira, com vertedouro em degraus e vertedouro de calha lisa. Os dados utilizados foram obtidos em modelo experimental, construído no Laboratório de Obras Hidráulicas (LOH) do Instituto de Pesquisas Hidráulicas (IPH-UFRGS), através de transdutores de pressões fixados junto ao fundo do canal de ensaios para diversas vazões, considerando, além de bacia tipo I, diferentes tamanhos de soleira terminal, situadas em diferentes posições do canal. / Stepped spillways have become a good option in dams for ease of construction and especially to present a significant dissipation of energy throughout the spillway chute, which causes that the parcel of energy to be dissipated by hydraulic jump downstream of dam decreases, causing a significant reduction in the dimensions of the stilling basin structure. The application of end sill in stilling basins causes a better distribution of speeds and better behavior of the fluctuation of pressure along the basin and downstream, thus increasing their performance in energy dissipation. The combination of these two forms of dissipation (stepped spillway and stilling basin with end sill) can be used as an economical and safe solution, however, the sizing of these structures hindered by a lack of criteria and information, especially regarding the ideal size and position for design of an end sill. In this study the data mean pressures and pressure fluctuations within the basin and downstream of the end sill were analyzed, being presented methodologies for design the size and position of a sill as a function of the Froude number of the input of the hydraulic jump. A methodology for analysis of mean pressure in type I basin (without sill) is also being presented, and a comparison of the behavior of efforts in basin with and without end sill, with stepped spillway and flat spillway chute. The data were obtained in an experimental model built at the Laboratory of Hydraulic Works (LOH) at the Institute of Hydraulic Research (IPH-UFRGS), through pressure transducers attached at the bottom of the test channel for various flow rates, considering, in addition of type I basin, different sizes of end sill at different positions of the channel.

Vertedouros em degraus têm se tornado uma boa opção em barragens pela facilidade de construção e, principalmente, por apresentar uma dissipação significativa de energia ao longo de sua calha, o que faz com que a parcela de energia a ser dissipada por ressalto hidráulico a jusante da barragem diminua, ocasionando uma significativa redução nas dimensões da estrutura da bacia de dissipação. A aplicação de soleira terminal em bacias de dissipação provoca uma melhor distribuição das velocidades e um melhor comportamento da flutuação de pressões ao longo da bacia e a jusante, aumentando assim seu desempenho na dissipação de energia. A combinação destas duas formas de dissipação (vertedouro em degraus e bacia de dissipação com soleira terminal) pode ser utilizada como uma solução econômica e segura, entretanto, o dimensionamento dessas estruturas esbarra na falta de critérios e informações, principalmente quanto ao tamanho e posição ideal para o projeto de uma soleira terminal. No presente trabalho foram analisados os dados de pressões médias e flutuações de pressões no interior da bacia e a jusante da soleira terminal, sendo apresentadas metodologias para dimensionamento de tamanho e para posicionamento de uma soleira em função do número de Froude da entrada do ressalto hidráulico. Também está sendo apresentada uma metodologia para análise das pressões médias em bacia do tipo I (sem soleira), além de uma comparação do comportamento dos esforços em bacia com soleira e sem soleira, com vertedouro em degraus e vertedouro de calha lisa. Os dados utilizados foram obtidos em modelo experimental, construído no Laboratório de Obras Hidráulicas (LOH) do Instituto de Pesquisas Hidráulicas (IPH-UFRGS), através de transdutores de pressões fixados junto ao fundo do canal de ensaios para diversas vazões, considerando, além de bacia tipo I, diferentes tamanhos de soleira terminal, situadas em diferentes posições do canal. / Stepped spillways have become a good option in dams for ease of construction and especially to present a significant dissipation of energy throughout the spillway chute, which causes that the parcel of energy to be dissipated by hydraulic jump downstream of dam decreases, causing a significant reduction in the dimensions of the stilling basin structure. The application of end sill in stilling basins causes a better distribution of speeds and better behavior of the fluctuation of pressure along the basin and downstream, thus increasing their performance in energy dissipation. The combination of these two forms of dissipation (stepped spillway and stilling basin with end sill) can be used as an economical and safe solution, however, the sizing of these structures hindered by a lack of criteria and information, especially regarding the ideal size and position for design of an end sill. In this study the data mean pressures and pressure fluctuations within the basin and downstream of the end sill were analyzed, being presented methodologies for design the size and position of a sill as a function of the Froude number of the input of the hydraulic jump. A methodology for analysis of mean pressure in type I basin (without sill) is also being presented, and a comparison of the behavior of efforts in basin with and without end sill, with stepped spillway and flat spillway chute. The data were obtained in an experimental model built at the Laboratory of Hydraulic Works (LOH) at the Institute of Hydraulic Research (IPH-UFRGS), through pressure transducers attached at the bottom of the test channel for various flow rates, considering, in addition of type I basin, different sizes of end sill at different positions of the channel.

abstract: Advancements in thermal interface materials (TIMs) allows for the creation of new and more powerful electronics as they increase the heat transfer from the component to the heat sink. Current industrial options provide decent heat transfer, but the creation of TIMs with higher thermal conductivities is needed. In addition, if these TIMs are elastic in nature, their effectiveness can greatly increase as they can deal with changing interfaces without degradation of their properties. The research performed delves into this idea, creating elastic TIMs using liquid metal (LM), in this case galinstan, along with other matrix particles embedded in Polydimethylsiloxane (PDMS) to create an easy to use, relatively inexpensive, thermally conductive, but electrically insulative, pad with increased thermal conductivity from industrial solutions. The pads were created using varying amounts of LM and matrix materials ranging from copper microspheres to diamond powder mixed into PDMS using a high-speed mixer. The material was then cast into molds and cured to create the pads. Once the pads were created, the difficulty came in quantifying their thermal properties. A stepped bar apparatus (SBA) following ASTM D5470 was created to measure the thermal resistance of the pads but it was determined that thermal conductivity was a more usable metric of the pads’ performance. This meant that the pad’s in-situ thickness was needed during testing, prompting the installation of a linear encoder to measure the thickness. The design and analysis of the necessary modification and proposed future design is further detailed in the following paper. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2017

Vertedouros em degraus têm se tornado uma boa opção em barragens pela facilidade de construção e, principalmente, por apresentar uma dissipação significativa de energia ao longo de sua calha, o que faz com que a parcela de energia a ser dissipada por ressalto hidráulico a jusante da barragem diminua, ocasionando uma significativa redução nas dimensões da estrutura da bacia de dissipação. A aplicação de soleira terminal em bacias de dissipação provoca uma melhor distribuição das velocidades e um melhor comportamento da flutuação de pressões ao longo da bacia e a jusante, aumentando assim seu desempenho na dissipação de energia. A combinação destas duas formas de dissipação (vertedouro em degraus e bacia de dissipação com soleira terminal) pode ser utilizada como uma solução econômica e segura, entretanto, o dimensionamento dessas estruturas esbarra na falta de critérios e informações, principalmente quanto ao tamanho e posição ideal para o projeto de uma soleira terminal. No presente trabalho foram analisados os dados de pressões médias e flutuações de pressões no interior da bacia e a jusante da soleira terminal, sendo apresentadas metodologias para dimensionamento de tamanho e para posicionamento de uma soleira em função do número de Froude da entrada do ressalto hidráulico. Também está sendo apresentada uma metodologia para análise das pressões médias em bacia do tipo I (sem soleira), além de uma comparação do comportamento dos esforços em bacia com soleira e sem soleira, com vertedouro em degraus e vertedouro de calha lisa. Os dados utilizados foram obtidos em modelo experimental, construído no Laboratório de Obras Hidráulicas (LOH) do Instituto de Pesquisas Hidráulicas (IPH-UFRGS), através de transdutores de pressões fixados junto ao fundo do canal de ensaios para diversas vazões, considerando, além de bacia tipo I, diferentes tamanhos de soleira terminal, situadas em diferentes posições do canal. / Stepped spillways have become a good option in dams for ease of construction and especially to present a significant dissipation of energy throughout the spillway chute, which causes that the parcel of energy to be dissipated by hydraulic jump downstream of dam decreases, causing a significant reduction in the dimensions of the stilling basin structure. The application of end sill in stilling basins causes a better distribution of speeds and better behavior of the fluctuation of pressure along the basin and downstream, thus increasing their performance in energy dissipation. The combination of these two forms of dissipation (stepped spillway and stilling basin with end sill) can be used as an economical and safe solution, however, the sizing of these structures hindered by a lack of criteria and information, especially regarding the ideal size and position for design of an end sill. In this study the data mean pressures and pressure fluctuations within the basin and downstream of the end sill were analyzed, being presented methodologies for design the size and position of a sill as a function of the Froude number of the input of the hydraulic jump. A methodology for analysis of mean pressure in type I basin (without sill) is also being presented, and a comparison of the behavior of efforts in basin with and without end sill, with stepped spillway and flat spillway chute. The data were obtained in an experimental model built at the Laboratory of Hydraulic Works (LOH) at the Institute of Hydraulic Research (IPH-UFRGS), through pressure transducers attached at the bottom of the test channel for various flow rates, considering, in addition of type I basin, different sizes of end sill at different positions of the channel.

Neste trabalho apresenta-se uma avaliação do estado da arte de aspectos hidráulicos relacionados aos vertedores em degraus submetidos aos diferentes regimes de escoamento. Em uma segunda parte, é sugerida uma metodologia adimensional e simplificada para o pré-dimensionamento do comprimento de bacias de dissipação por ressalto hidráulico, além de uma abordagem conceitual voltada ao escoamento sobre um degrau. Entre os tópicos tratados na avaliação do estado da arte, pode-se citar, por exemplo, a dissipação de energia promovida pelos degraus, o risco de cavitação, a aeração do escoamento, o uso de aeradores de fundo e geometrias não convencionais. Quanto à metodologia desenvolvida, fundamentada na segunda lei do movimento de Newton associada à equação de Darcy-Weisbach, apresenta-se algumas comparações com dados experimentais de diferentes pesquisadores, além de exemplos de aplicação. Foi possível concluir, com a avaliação do estado da arte, que há um interesse crescente pelo conhecimento das características hidráulicas de vertedores em degraus. Através da metodologia desenvolvida, graças às comparações com dados experimentais de diferentes pesquisadores, foi possível concluir que não há um consenso absoluto sobre a magnitude do fator de resistência de Darcy-Weisbach. Com os exemplos de aplicação apresentados, notou-se que para um mesmo problema, o uso de diferentes métodos pode conduzir a projetos significativamente diferentes. / This work presents a state-of-the-art evaluation of aspects related hydraulic to stepped spillways submitted to the different flow regimes. In a second part, it is suggested a dimensionless and simplified methodology for preliminary design of the stilling basin length, besides a conceptual approach related to the free fall hydraulics. Among topics treaties in the state-of-the-art evaluation, it can cite, for example, the energy dissipation promoted by the steps, incipient cavitation, the air entrainment, the use of bottom aerator and unconventional geometries. Regarding the developed methodology, based in the Newton\'s law of motion associate to Darcy-Weisbach equation, it presents some comparisons with experimental data of different researchers, besides application examples. It was possible to conclude, with the state-of-the-art evaluation, that there is an increasing interest for hydraulics characteristic of stepped spillways knowledge. Through the developed methodology, after comparisons with experimental data of different researchers, was possible to conclude that there is not an absolute consensus about the Darcy-Weisbach friction factor magnitude. With the application examples, it noticed that for a same problem, the different methods use can lead for significantly different designs.

Este trabalho traz contribuições experimentais, numéricas e teóricas acerca dos escoamentos turbulentos em canais e vertedores em degraus. Com a exposição de resultados de diferentes autores, procurou-se apresentar uma visão histórica sobre a evolução do conhecimento ligado ao tema, bem como o seu estado-da-arte. Os resultados experimentais foram obtidos em um canal em degraus com 1V:1H. Procurou-se investigar o comportamento da superfície livre com o uso de um medidor ultrassônico de deslocamentos. Foi possível obter perfis médios bem definidos, compostos por um trecho inicial com a forma S2 e S3 e um trecho ondulado a partir do início da aeração superficial. Esses perfis formados por valores médios levaram à definição de profundidades características que compõem a onda e de um comprimento de transição ao escoamento bifásico entre o final do perfil S2 e o primeiro pico da onda. As comparações dos dados experimentais deste trabalho e dos resultados experimentais e numéricos de outros autores, referentes à posição de início da aeração e à altura de escoamento nesta posição, indicaram haver excelente concordância entre as diferentes propostas. Foram fornecidas expressões empíricas para a maior parte das quantidades medidas. Além dos valores médios, os sinais instantâneos obtidos com o ultrassom foram também analisados, tendo sido possível extrair informações sobre a distribuição da intensidade turbulenta, energia cinética turbulenta, número de Strouhal e coeficientes de assimetria e curtose. Estas quantidades estatísticas revelaram diferentes regiões ao longo do canal em degraus, incluindo a região de decaimento das mesmas, com posição final coincidente. Como resultado foi proposta uma expressão para calcular a posição vertical do início do escoamento uniforme. A segunda parte desta tese contém uma revisão sobre as equações e princípios básicos de mecânica dos fluidos e sobre aspectos essenciais relacionados a soluções numéricas. Ao comparar os resultados experimentais com soluções numéricas das equações de Navier-Stokes médias de Reynolds, conservação de massa e diferentes modelos de turbulência, concluiu-se haver excelente sobreposição das soluções aos experimentos. Isto foi possível com o uso do modelo não homogêneo para o escoamento com superfície livre e com os modelos de turbulência k-&#949, RNG k-&#949, SSG e zero-equação. Em seguida, utilizando-se o modelo k-&#949, foram realizadas simulações numéricas em domínios que correspondem a vertedores sem comportas e com dimensões de protótipo. Explorou-se também o uso do referido conjunto de equações na obtenção de informações sobre escoamentos em quedas sucessivas. Neste caso a análise dos resultados se concentrou nas profundidades ao longo do canal e da energia residual. A terceira parte da tese contém proposições e considerações teóricas e semi-empíricas. Entre elas, pode-se mencionar que foram apresentadas equações para previsão de perfis da superfície livre, fator de resistência, comprimento de transição, desenvolvimento da camada limite e coeficiente de reoxigenação. Finalmente, o último capítulo antes das conclusões traz discussões acerca dos três pontos de vista: experimental, numérico e teórico. / This work includes contributions from experimental, numerical and theoretical studies about turbulent flows in stepped chutes and spillways. Initially, previous results and proposals of different authors are presented, intending to furnish an overview of the historical evolution of the knowledge in this theme and its state-of-the-art. The experimental results were obtained in a stepped channel with step ratio 1V:1H. The behavior of the free surface was investigated using an ultrasonic displacement meter. It was possible to obtain well-defined time-averaged profiles, comprising a first stretch with the S2 and S3 forms, and a second wavy stretch, which was produced by the surface aeration. These profiles consist of average depths, and led to the definition of characteristics depths for the first \"wave\" and to a transition length between the end of the S2 profile and the first peak of the wavy region. Comparisons between the experimental data obtained in this study and experimental and numerical results of other authors, regarding the inception point and the water depth at this position, indicated excellent agreement between the different proposals. Empirical expressions are proposed here for most of the measured parameters. In addition to the analysis of the average values, also the instantaneous signals obtained with the ultrasound sensor were analyzed; allowing to obtain information about the distribution of the turbulent intensity, the turbulent kinetic energy, the Strouhal number, and the coefficients of skewness and kurtosis. The behavior of these statistical quantities revealed different regions along the stepped chute, and a final region of decay coincident for all quantities. As a result, an expression was proposed to calculate the vertical position of the beginning of the uniform flow. The second part of this thesis contains a review of the basic principles and equations of fluid mechanics and some key aspects related to numerical solutions. By comparing the experimental results with the numerical solutions of the Reynolds Averaged Navier-Stokes equations, the conservation of mass, and different turbulence models, it was concluded that there exist an excellent superposition between the numerical predictions and the experiments. This was made possible using an inhomogeneous model for the free surface flow and the turbulence models k-&#949, RNG k-&#949, SSG and zero-equation. Further, using the k-&#949 model, numerical simulations were carried out for uncontrolled spillways (without gates), considering prototype dimensions. The same set of equations was used for skimming flows and nappe flows. In the second case, the analysis focused on the water depths along the channel and on the residual energy. The third part of the thesis contains theoretical and semi-empirical formulations based on fluid mechanics\' principles. The presented equations are for predictions of free surface profiles, resistance factors, transition lengths, development of boundary layer and reaeration. Finally, the last chapter before the conclusions presents discussions about the three points of view: experimental, numerical and theoretical.

This thesis introduces, for the first time, Stepped Impedance Resonator (SIR) bandpass filters (BPF) based on Composite Right/Left-Handed (CRLH) transmission lines. In other words, a novel approach in design of BPFs for RF and microwave applications is successfully proposed and examined, which can serve both miniaturisation and performance enhancement purposes. In conducting this research, design, development and optimisation procedures and techniques for the proposed BPFs have been presented. Theoretical, numerical and experimental results have confirmed that these filters are capable of significantly reducing the size while maintaining the integrity of the filter performance; and in some cases, extensively enhancing the performance.Two λg/4-type CRLH SIRs are designed and characterised based on the available equations. ADS lumped-element equivalent circuit model and HFSS full-wave electromagnetic simulation, and measurement results prove that both CRLH SIRs surpassed their RH counterparts, in terms of both size and performance. Indeed, comparison of the first CRLH SIR with its RH counterpart revealed a 35% size (length) reduction. The second CRLH SIR design is measured to be 66% smaller than its RH counterpart and 14% smaller than the initial CRLH SIR. In addition, simulation and measurement results reveal that an intelligently designed CRLH SIR shows a better quality factor Q and input impedance |Zin| response, and provides higher design flexibility. Phase unwrapping and energy (current) flow analysis have been used to prove left-handedness of the CRLH SIRs. The concept is extended to propose multi-section (λg/2-type and tri-section SIRs) and tunable CRLH SIRs. Numerical analysis and obtained results show that the λg/2-type CRLH SIR benefits from a 45% size (length) reduction compared to its RH counterpart, and a better |Zin| response. The results obtained from the tri-section CRLH SIR (TSSIR), clearly show that the TSSIR is capable of relocating (and minimising) the multiple spurious resonance frequencies, while maintaining the same fundamental frequency f0. As such, no spurious frequency is observed before 8 GHz. Also, measurements indicated that the CRLH TSSIR is not only 30% smaller in length compared to its RH counterpart, it was even 28% smaller than a two-section RH SIR resonating at the same frequency of 2.5 GHz. In addition, the tuning capability of the ferrite CRLH SIR is illustrated when the operating frequency of the resonator is tuned from 5.1 GHz to 5.4 GHz, and 5.65 GHz for H0 = 2000, 2250, and 2500 Oe, respectively.These SIRs are then combined and configured to form two main categories of CRLH SIR bandpass filters: PCB filters based on RT Duroid and MMIC filters based on GaAs. In both filters, the homogeneity condition has been satisfied by ensuring that the longest length is much less than λg (in this case l = λg/12) for PCB-based filters and l = λg/14 for MMIC filters at the centre frequency of the filters. The first PCB-based CRLH SIR filter, which has been designed to operate at 2.75 GHz, is measured 24mm × 28mm. HFSS 3-D full-wave simulations and measurement results of this filter reveal that, with an insertion loss of -2.6dB and return loss of -21.5dB, the filter not only has a very good selectivity, but also is extremely efficient in extending the free-spurious stop-band, pushing the first spurious response to around 11 GHz (about 4×f0). The second PCB-based CRLH SIR filter has much smaller size, measuring overall filter dimensions of 6mm × 5.14mm. This filter also benefits from a smaller resonator size, improved overall coupling and a more controllable circuit. Theory, full-wave simulation and measurement results demonstrate that, with an insertion loss of -1dB and return loss of -34dB, the miniaturised CRLH SIR filter proves very successful as it was about 80% smaller in size compared to its RH counterpart with the same centre frequency, while maintaining the integrity of the filter performance. Moreover, the miniaturised CRLH SIR BPF is significantly more controllable in its dimensions and response due to the fact that more elementary parameters are available in the CRLH configuration.The MMIC CRLH SIR bandpass filters are then proposed with an emphasis on further size reduction with maintenance (or enhancement) of their transmission responses. As such, two classes of MMIC filters were designed: the first one is very small measuring 3.2mm × 3.4mm, with an insertion loss of -5.3dB at the centre frequency 3.1 GHz. The filter also shows good attenuation both before and after the passband with its first spurious frequency occurring at 13.52 GHz (i.e. > 4×f0). The second set of MMIC filters employed multilayer topology to reduce the filter size. It has been clearly shown that with an intelligent design, the size (dimension) limitations of the PCB-based filters have been overcome by using the MMIC technology, resulting in filters with significantly reduced sizes - design I: 1.32mm×3.35mm, and design II: 1.4mm × 1.5mm. It has also been observed that MMIC structures are generally exposed to inevitable losses, though steps can be taken to reduce such losses.

Stepped care is designed to provide mental health treatment in the most effective and efficient way. It aims to provide patients with low intensity interventions in the first instance and only move onto high intensity treatments if outcome is not 'successful'. However, there is a paucity of research about how health professionals make decisions about treatment and the experiences of patients within this decision-making process. Using a multi-method approach, this study aimed to explore health professional and patient decision-making in stepped care for anxiety and depression. 24 health professional interviews from three stepped care sites were conducted, which included the completion of an active information search (AIS) think-aloud task. In addition, 14 patients were interviewed about their experiences of decision-making whilst being managed within stepped care model. Qualitative interview data was analysed using the principles of Framework analysis, while some of the data collected in the AIS think-aloud task lent itself to quantitative analysis.This study revealed that three core tensions exist when making decisions within the stepped care model. These are 1. The notion of standardisation of outcomes versus the individual needs of patients; 2. The public health orientation of stepped care versus the therapeutic orientation of health professionals and; 3. The rhetoric about patient choices versus the realities of shared decision-making in a resource-limited system.The complexity of decision-making within the stepped care model was highlighted. The success of stepped care relies on ensuring that there is an adequate workforce to deliver the intended interventions, where this is not present health professionals are faced with difficult decisions and it is clear that those most affected are the less-experienced frontline workers. Scarcity of resources impacts heavily upon the decisions that are made. This can have a substantial impact upon variability in treatment decisions and on the ability to allow for patient choice to be incorporated. Decisions that are made for a patient are influenced by the need to provide them with the treatment that they want (which may not be regarded as what they need within the stepped care model nor necessarily by the health professional) and the capacity of the service. The problem that exists with primary care mental health is that the current demands exceed capacity. Optimal patient care is, in part, traded off by the need to meet the demands of the service. Improving the flexibility of the service may be one solution to the problem and adopting a stratified/stepped care approach might help to resolve some of the tensions and help to relieve some of the capacity issues.