Proper positioning of Microelectromechanical Systems (MEMS) components influences the functionality of the device, especially in devices where the motion is in the range of hundreds of micrometers. There are two main obstacles to positioning: off-axis displacement, and position determination. This work studies four large-displacement devices, their axial and transverse stiffness, and piezoresistive response. Methods for improving the device characteristics are described. The folded-beam suspension, small X-Bob, large X-Bob and double X-Bob were characterized using non-dimensional metrics that measure the displacement with regard to the size of the device, and transverse stiffness with regard to axial stiffness. The stiffness in each direction was determined using microprobes to induce displacement, and microfabricated force gauges to determine the applied force. The large X-Bob was optimized, increasing the transverse stiffness metric by 67%. Four-point resistance testing and microprobes were used to determine the piezoresistive response of the devices. The piezoresistive response of the X-Bob was maximized using an optimization routine. The resulting piezoresistive response was over seven times larger than that of the initial design. Piezoresistive encoders for ratcheting actuation of large-displacement MEMS are introduced. Four encoders were studied and were found to provide information on the performance of the ratcheting actuation system at frequencies up to 920 Hz. The PMT encoder produced unique signals corresponding to distinct ideal and non-ideal operation of the ratchet wheel actuation system. Encoders may be useful for future applications which require position determination.

The purpose of this research is to investigate the use of compliant mechanisms in space applications and design, analyze, and test a compliant space mechanism. Current space mechanisms are already highly refined and it is unclear if significant improvements in performance can be made by continuing to refine current designs. Compliant mechanisms offer a promising opportunity to change the fundamental approach to achieving controlled motion in space systems and have potential for dramatic increases in mechanism performance given the constraints of the space environment. A compliant deployment hinge was selected for development after industry input was gathered. Concepts for large-displacement compliant hinges are investigated. A design process was developed that links the performance requirements of deployment to the design parameters of a deployment hinge. A large-displacement monolithic compliant rotational hinge, the Flex-16, is designed, analyzed, and tested. It was developed for possible application as a spacecraft deployment hinge and designs were developed using three different materials (polypropylene, titanium, and carbon nanotubes) and manufacturing processes (CNC milling, electron beam manufacturing metal rapid prototyping, and a carbon nanotube framework) on two size scales (macro and micro). A parametric finite element model allowed for prediction of prototype behavior before fabrication. The Flex-16 hinge is capable of 90 degrees of deflection without failure or contact and can be designed to meet industry requirements for space.

[pt] O deslocamento de um líquido por outro em espaços anulares é comumente encontrado na indústria do petróleo, e a maioria deles envolve materiais não newtonianos. O espaço anular muitas vezes apresenta irregularidades causadas pela erosão, onde quantidades consideráveis de fluido de perfuração podem ser deixadas para trás durante o processo de deslocamento, comprometendo a qualidade da operação de cimentação. Motivados por esse processo industrial, testes de deslocamento entre líquidos a vazão constante foram realizados em espaços anulares cuja parede externa possui, em uma determinada posição axial, um aumento repentino de diâmetro seguido de uma diminuição repentina de diâmetro mais a jusante. O objetivo dos experimentos era determinar a eficiência do deslocamento em função da vazão, reologia dos fluidos e geometria da cavidade. Os resultados revelaram forte influência desses parâmetros na eficiência de deslocamento. Ao mesmo tempo, um estudo numérico foi desenvolvido. Simulações numéricas das equações de Navier-Stokes em geometria axissimétrica para fluidos incompressíveis foram acopladas ao método Level-Set para captura da interface. Fluidos com viscosidade constante e o modelo newtoniano generalizado com função viscosidade de Carreau-Yasuda foram utilizados. Isso permitiu simular deslocamentos entre dois fluidos newtonianos e entre um fluido newtoniano e outro não-newtoniano. Este foi utilizado tanto como fluido deslocador quanto como deslocado. Foram realizadas simulações para várias razões de diâmetros, viscosidades, tempos de relaxação, e números de capilaridade e de Reynolds. Identificamos quando a aproximação do espaço anular por duas placas paralelas pode ser aplicada e calculamos como a forma da interface depende dos parâmetros investigados. / [en] The displacement of a fluid caused by another one, inside annular spaces, is commonly found in the oil industry and most of these rearrangements involve non-Newtonian materials. The annular space often shows irregularities caused by erosion, in which considerable amounts of drilling fluid can be left behind during the displacement process, compromising the cementing operation efficiency. Motivated by that industrial process, fluid-fluid displacement tests at constant flow rate were performed in annular spaces in which their exterior walls displayed - in a determined axial position - an abrupt expansion followed by an abrupt contraction. The purpose of the tests were to determine the displacement efficiency as a function of flow rate, rheological properties and geometric cavity. The results revealed a strong influence of these parameters on the displacement efficiency. At the same time, a numerical research was developed. Numerical simulations of the Navier-Stokes equations in axisymmetric geometry for incompressible fluids were coupled to the Level-Set method to capture the interface. Fluids with constant viscosity and the generalized Newtonian model with viscosity function of Carreau-Yasuda were used. That allowed to simulate displacements between two Newtonian fluids and a Newtonian and a non-Newtonian fluid. This was used both as a displacer and as a displaced fluid. Simulations were performed for several diameters and viscosities ratios, relaxatation time, capilar and Reynolds numbers. We identified when the approximation of the annular space by two parallel plates can be applied and calculated how the shape of the interface depends on the investigated parameters.

[pt] Obras de infraestrutura, que se apresentam como indutoras de desenvolvi-mento, frequentemente resultam em deslocamento involuntário e reassentamento de pessoas que ocupam ou dependem da área em questão. Tais processos de deslocamento e reassentamento podem estar associados a impactos adversos, gerando empobrecimento para as pessoas afetadas, bem como podem gerar oportunidades de desenvolvimento, não apenas para a região que se beneficiará das novas infra-estruturas instaladas, mas também para as pessoas afetadas física e/ou economicamente. Entender a engrenagem e a dinâmica de deslocamentos involuntários e reassentamentos e os fatores que contribuem para que tais processos resultem em impactos negativos ou positivos é fundamental para implementar planos de reassentamento que efetivamente gerem oportunidades e contribuam para processos de desenvolvimento integral. Alguns aspectos são fundamentais nesta discussão, entre eles (i) planejamento eficaz e participativo, com engajamento da comunidade afetada em todas as etapas do processo; (ii) compensação e restauração dos padrões de vida e meios de subsistência para além de compensação monetária; (iii) monitoramento e acompanhamento antes, durante e após o processo do deslocamento e reassentamento. É imperativo que se adote uma abordagem mais holística para o reassentamento, que conduza tal processo como um programa de desenvolvimento. / [en] Infrastructure projects presented as inducers of development often result in involuntary displacement and resettlement of people who occupy or depend on the area. Such displacement and resettlement processes can be associated with adverse impacts, resulting in impoverishment of the affected people, as well as it can generate development opportunities, not only for the region that will benefit from the new infrastructure, but also for the people physically and /or economically displaced. Understanding the gear and dynamics of involuntary displacement and resettlement and the factors that contribute for these projects to result in adverse or positive impacts is essential to implement resettlement programmes that effectively generate opportunities and contribute to development. Some key aspects to be considered in this discussion are (i) effective and participatory planning, with the engagement of the affected people in all stages of the process; (ii) compensation and restoration of living standards and means of subsistence in addition to monetary compensation; (iii) monitoring before, during and after the displacement and resettlement process. It is imperative to adopt an holistic approach to development-induced resettlement which conducts such process as a development program.

Drawing from the ever-evolving processes that reproduce and re-define our everyday life in our living environment, this study explores the reverberations of flagship projects in the wider urban landscape. The power structures that formulate spatial production are discussed. Flagships are viewed as tangible representations of governmental and public authorities’ strategies. In-depth understanding of the consequences that stem from such implementations evidence the power dynamics in urban development processes. Stockholm’s vision for 2040 envisages the reinforcement of democratically sustainable development. This study delves into the socio-spatial earmarks that emerge from leading urban development projects in the wider urban landscape and more specifically in the adjoining to the project areas. To do so, this research looks into the urban development of the districts adjoining two large-scale projects, the Hammarby Sjöstad and the Royal Seaport.

How can we as architects interact with external practices, such as video games? Are there relevant aspects to be found, and what are the ways in which they could be approached? This project grounds itself in three different personal interests; architecture, digital design tools and video games, or more specifically: ”What kind of architectural expressions and spaces could be created if we design in the borderland between the real and the virtual game?” This is an experimental project that approaches a few aspects of video game design, as well as potential qualities of virtual worlds. It concerns itself with image based digital massing, level design as basis for program or composition on site, as well as being on the border between the real and the virtual. The result of the investigations is a playful collection of objects, arranged according to a loose, narrative sequence idea. The scene is geographically tied to a real location, but floats in a no-man’s-land between reality and game. In its current state, it is not a proposal for the actual, real world site, and at the same time it is not quite a game either. There is an ambivalence to the scene being at the pivot point of these two definitions. The objects have a structural and aesthetic nature that touches on low-polygon shapes as expression, using images for generating a grid-surface based outcome and exploring a transitioning between reality and virtuality through architectural representation.

This qualitative study sought insights into forced migrant youths’ sense of belonging. The study was part of the Youth Migration Project, an ongoing investigation of how young forced migrants construct their identities, sense of belonging, and future aspirations while perched on the edge of mainstream society – without normative entitlements or a voice in decision-making about their futures. Through purposive and snowball recruitment methods, the project gathered narratives of 52 forced migrant youth aged 11 to 17 who were born in conflict areas of Asia and Africa, primarily in Myanmar, Afghanistan, Syria, Pakistan, Iran, and Somalia. In the present study, I focused on the experiences of eight forced migrant female participants living in prolonged displacement in Malaysia. My guiding research question was: How do the processes and experiences of forced migration shape migrant youths’ sense of belonging? Through a mixed-method approach, including a novel, arts-based peer-mediated storyboard narrative method, now known as Storyboard Peers, and follow-up interviews, youth shared their migration narratives, the challenges they faced while living in Malaysia, and their expectations and aspirations for their futures. The theme of safety figured prominently in the girls’ accounts and I constructed the themes of physical safety and social safety to represent the data the girls contributed. The girls’ sense of belonging and feeling at home had a direct relationship with feeling safe, valued, and loved. I also found that their physical and social environments informed their sense of belonging. Sense of belonging is neither a static nor a fixed concept; rather it is a flexible, everchanging, and reconstructed with ongoing, everyday experiences, reflections on the past, and anticipations of what the future could hold. The girls’ accounts conveyed that feelings of “belongingness” and “at home” shifted from tangible places and familiar faces to abstract concepts such as love, peace, and family. Overall, feeling safe and “at home” were rooted in basic needs being met. My findings lead me to call for governments and nongovernmental organizations to significantly reduce the length of time that youth spend in transit, promote safety, combat discrimination, fulfill basic needs, and ensure access to education and healthcare. / Graduate

The ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on providing a way of assessing the reduction in capacity for main-shocks as compared to aftershocks and the effects and importance of both in a bridge. The reduction in capacity was defined using three different ratios: ultimate force, stiffness, and strain energy ratio. The ratios were computed relative to an undamaged state following both the main-shock scenario and the main-shock combined with aftershock scenario. The force, stiffness, and strain energy quantities were obtained from lateral pushover analyses along the two lateral bridge axes. Probabilistic demand models describing the loss in capacity were formulated by pairing intensity measures, based on real ground motions obtained from previous earthquakes, for the main-shock and aftershock with the capacity ratios, obtained from nonlinear dynamic time history analysis. Additionally, the reduction in capacity was conditioned on residual displacement and intensity measure in an attempt to discover the reduction in capacity ratio due to the contribution of residual displacement and therefore separate contributions from geometrical and material nonlinearities. This thesis demonstrates that the usage of strain energy ratio provides a definition of capacity that ultimately provides the best correlation between capacity and intensity measure.

The design and implementation of a micro-force displacement system was completed to test the force-displacement characteristics of square silicon diaphragms with side lengths of 4mm, 5mm, and 7mm with a thickness of 10um. The system utilizes a World Precision Instruments Fort 10g force transducer attached to a World Precession Instruments TBM4M amplifier. A Keithley 2400 source meter provided data acquisition of the force component of the system. A micro prober tip was utilized as the testing probe attached to the force transducer with a tip radius of 5um. The displacement of samples was measured using a Newport M433 linear stage driven by a Newport ESP300 motion controller (force readings at constant displacement intervals). An additional 3 linear stages were used to provide X and Y-axis positioning of samples beneath the probe tip. The system components were mounted to an optical bench to provide stability during testing. C# was used to deliver the code to the individual components of the system. In addition the software provides a graphic user interface for future users that includes a calibration utility (both X/Y and force calibration), live force-displacement graph, motion control, and a live video feed for sample alignment. Calibration of the force transducer was accomplished using an Adam Equipment PGW153e precision balance to assign force values to the voltage data produced from the transducer. Displacement calibration involved the use of a microscope calibration micrometer. The system was characterized with an equipment variability of ±1.02mg at 1.75um, and ±1.86mg at 3.5um with the ability to characterize samples with stiffness less than 279 mg/um. The displacement resolution of the system was determined to be 35 nm per step of the linear stages. The diaphragms created to test the machine were fabricated from 10um thick device layer SOI wafers. An etch consisting of 38g/l silicic acid, 7g/l ammonium persulfate, and 5% TMAH was used to reduce the formation of hillocks, and provide a consistent etch rate. A Gage R&R study was performed on the fabricated diaphragms, indicating that the deflection produced by the 4mm, 5mm, and 7mm diaphragms was resolvable by the machine. A model was developed to correlate theoretical results to the observed measured values.

Coastal areas are vulnerable to different natural hazards, including hurricanes, cyclones, tsunami, floods, coastal erosion, and saltwater intrusion. These hazards cause extensive social, ecological, economic, and human losses. Continued climate change and sea-level rise is expected to substantially impact the people living in coastal areas. Sea level rise poses serious threats for the people living in the coastal zone, which leads to coastal erosion, inundations in the low-lying areas, tidal water encroachment and subsequent salt-water intrusion, as well as the displacement of the people living along the coast. Coastal erosion is one of the biggest environmental threats in the coastal areas globally. In Bangladesh, coastal erosion is a regularly occurring and major destructive process, impacting both human and ecological systems at sea level. The Lower Meghna estuary, located in southern Bangladesh, is among the most vulnerable landscapes in the world to the impacts of coastal erosion. Erosion causes population displacement, loss of productive land area, loss of infrastructure and communication systems, and, most importantly, household livelihoods. For a lower middle-class country, such as Bangladesh, with limited internal resources, it is hard to cope with catastrophic natural hazards, such as coastal erosion and its related consequences. This research aims to advance the scientific understanding of past and future coastal erosion risk and associated changes in land change and land cover using geospatial analysis techniques. It also aims to understand the patterns and drivers of human perception of coastal erosion risk. To place the research questions and objectives in content, Chapter 1 includes a brief introduction and literature review of the coastal erosion context in Bangladesh. Chapter 2 assesses different methods of prediction to investigate the performance of future shoreline position predictions by quantifying how prediction performance varies depending on the time depths of input historical shoreline data and the time horizons of predicted shorelines. Chapter 3 evaluates historical land loss and how well predicted shorelines predict amounts of succeeding LULC resources lost to erosion. Chapter 4 focuses on the patterns and drivers of erosion risk perception using data from spatially explicit measures of coastal erosion risk derived from satellite imagery and a random sample survey of residents living in the coastal communities. In summary, this research advances our scientific understanding of past and future coastal erosion risk and associated changes in land change and land cover using geospatial analysis techniques. It also enhances the understanding of the patterns and drivers of human perception of coastal erosion risk by combining satellite imagery and social survey data. Compared to much of the coastal erosion literature, this work draws from a 35-year time series of satellite-derived shorelines at annual temporal resolution. This time depth enables us to employ a temporal design strategy expected to yield a robust characterization of space-time erosion patterns. This study also enabled us to assess how well predicted shorelines predict amounts of succeeding LULC resources lost to erosion by using long-term historical data. The innovative we use has potential applications to other deltas and vulnerable shorelines globally. While empirical results are specific to the project's study area, results can inform the region's shoreline forecasting ability and associated mitigation and adaptation strategies. / Doctor of Philosophy / Coastal erosion is a global problem. Coastal Bangladesh has one of the highest rates of erosion in the world. Erosion causes population displacement, loss of productive land area, loss of infrastructure and communication systems, and, most importantly, household livelihoods. With an aim to advance our understanding of coastal erosion hazard, this study assessed past and future coastal erosion risk and associated changes in land change and land cover and human risk perceptions using different geospatial and statistical analysis techniques. First, different methods of coastal erosion prediction were evaluated to investigate the performance of future shoreline position predictions. Second, the historical land loss was estimated and how well predicted shorelines predict amounts of succeeding LULC resources lost to erosion were assessed. Finally, the patterns and drivers of human perception of coastal erosion risk were explored.