Numerical and experimental study on electrokinetic phenomena in micro scales

Fernandes, Dolfred Vijay Dong-A Univ. 2012 국내박사

Building Brasilia: Modern architecture and national identity in Brazil

Fernandes, Ines Palma Princeton University 2003 해외박사(DDOD)

The creation of Brazil's national capital Brasília is the best-known achievement of Brazilian architecture. Following its inauguration in April 1960 Brasília became the focus of international debate. Up to the present moment this important chapter of world architecture and criticism has been little more than a footnote in the annals of architectural history. The present dissertation aims to fill this historiographic gap within the domain of architectural history, theory and criticism. The building of Brasília in the 1950's was both a confirmation of the country's wide acceptance of International Modernism and a demonstration of a very particular development of Modernism—one that assimilated cultural characteristics and regional requirements. The first part of the dissertation, “Modern Architecture in Brazil,” analyzes how this quality of being <italic> modern</italic> and <italic>truly Brazilian</italic> remains at the heart of Brasilia's symbolism and of the Brazilian Modern Movement in general. It also examines the particular contributions of Brasília's architects, Lúcio Costa and Oscar Niemeyer, in the formulation of a “national style”. The second part, “Building a New Brazil” looks into the political and socio-economic expectations permeating the creation of the new Brazilian capital from the 18<super>th</super> to the 20<super>th</super> century. The third part, “Brasília 1960: The City Miracle and Capital of the Future” focuses on the conception, construction and inauguration of the capital city between 1957 and 1960 and provides a panorama of the city's social history until the end of the democratic regime in 1964. The fourth part, “Brasília Today: The City Monument,” traces the development of Brasília from 1964 until today and presents the most recent renovation and expansion projects presumably to be built in the city within the next few years. The fifth and final part of the dissertation, “The Critical Discourse” traces the critical and contradictory reception of Brasília in the national and international professional circles. The concluding remarks discuss the various perspectives that have mediated the discourse on Brasília throughout, and provide an updated criticism of the Brazilian enterprise.

The spatial structure of turbulent Rayleigh-Benard convection

Fernandes, Richard Lawrence Joseph University of Illinois at Urbana-Champaign 2001 해외박사(DDOD)

The main objective of this study was to examine the spatial structure of turbulent Rayleigh-Benard convection in a high aspect-ratio experimental cell. Particle-image velocimetry was used to obtain an ensemble of velocity fields that was used to calculate the two-point velocity correlation tensor <italic>R_ij</italic>(<bold>x</bold>,<bold>x<super>′ </super></bold>). Proper orthogonal decomposition and linear stochastic estimation were used to interpret the information contained in the velocity correlation tensor. Turbulent Rayleigh-Benard convection in high aspect-ratio cells was found to be horizontally homogeneous, statistically axisymmetric about the vertical axis, and reflectionally symmetric about vertical planes. The visualization of the large-scale motions by linear stochastic estimation was consistent with vertical sections through circulation cells encompassing the layer depth. The two-dimensional proper orthogonal decomposition (POD) of the velocity correlation tensor was used to examine the distribution of turbulent kinetic energy among the scales. The large scales, represented by the low-order POD modes, were found to contain most of the kinetic energy. In particular, the nine lowest-order modes, which represent less than 0.1% of the total number of modes in the decomposition, carry approximately 60% of the energy. The large-scale structures, which were visualized by projecting individual PIV realizations onto a small set of the low-order modes, were consistent with vertical sections through circulation cells that encompass the layer depth. The circulation cells visualized in the present study are a manifestation, in the fully turbulent regime, of the cellular structures commonly observed at low Rayleigh numbers. The circulation cells are proposed as a physical description (not an explanation) of the phenomenon referred to in the literature as the <italic>wind of turbulence</italic>. They were found to contain approximately 40% of the total kinetic energy, and this fraction was found to be approximately independent of the Rayleigh number. This leads to the conclusion that the wind of turbulence (<italic>U</italic>) scales with the velocity fluctuations (<italic>u</italic>_fluct), <italic>U</italic> ∼ <italic>u</italic>_fluct. The visualizations indicate that the large-scale circulation engulfs the small-scale structures and advect them across the layer. The engulfment of small-scale buoyant elements may be the mechanism by which the large-scale circulation obtains the buoyancy required to maintain its kinetic energy.

Preserved implicit semantic differentiation in an alexic Wernicke's aphasic

Fernandes, Leyan Oi Lin University of Illinois at Urbana-Champaign 1999 해외박사(DDOD)

Lesions of Wernicke's area are typically associated with functional impairments in word comprehension. These impairments are traditionally assessed with neuropsychological measures that examine overt behavioral responses. The aspects or stages of semantic categorization processes that are disrupted, however, are unknown. These were probed with event-related brain potentials in a case of alexic Wernicke's aphasia. At 10 weeks post-infarct, the patient performed 3 tasks: a 2-category, non-semantic visual oddball; a 3-category, semantic visual oddball; and a word-to-picture card-sorting task. ERPs collected during the oddball tasks were analyzed using the bootstrap method, a non-parametric technique for estimating a population distribution from a single sample's data. In the non-semantic oddball paradigm, which served as a baseline for the semantic oddball paradigm, a classic P300 probability effect was obtained. In the semantic oddball paradigm, where the subject was asked to decide whether words were animals, N400 was larger for semantically anomalous fish words than for frequent mammal words. Evidence for P300 enhancement for rare, semantically distinct musical instrument words was not decisive. Response accuracy revealed no misclassifications of stimuli during the non-semantic task, but overt performance approximated chance for the semantic oddball and card-sorting tasks. The dissociation of N400 and overt performance reveals that implicit semantic differentiation can be preserved in alexic Wernicke's aphasia.

A Deliberative Account of Causation: How the Evidence of Deliberating Agents Accounts for Causation and its Temporal Direction

Fernandes, Alison Sutton Columbia University 2016 해외박사(DDOD)

In my dissertation I develop and defend a deliberative account of causation: causal relations correspond to the evidential relations we use when we decide on one thing in order to achieve another. Tamsin's taking her umbrella is a cause of her staying dry, for example, if and only if her deciding to take her umbrella for the sake of staying dry is adequate grounds for believing she'll stay dry. I defend the account in the form of a biconditional that relates causal relations to evidential relations. This biconditional makes claims about causal relations, not just our causal concepts, and constrains metaphysical accounts of causation, including reductive ones. Surely we need science to investigate causal structure. But we can't justify any particular account of causation independently of its relevance for us. This deliberative account explains why we should care about causation, why we deliberate on the future and not the past, and even why causes come prior in time to their effects. In chapter 1 I introduce the motivations for the project: to reconcile causation and our freedom as agents with the picture of the world presented by physics. Fundamental physics makes no mention of causes. And the lawlike character of the world seems to rule out freedom to decide. My dissertation offers a combined solution---I explain our freedom in epistemic terms and use this freedom to make sense of causation. In chapter 2 I draw on philosophy of action and decision theory to develop an epistemic model of deliberation, one based in requirements on belief. If we're to deliberate, our beliefs can't epistemically settle how we'll decide, yet our decisions must epistemically settle what we'll do. This combination of belief and suspension of belief explains why we rationally take ourselves to be free to decide on different options in deliberation. In chapter 3 I defend this model from near rivals that also explain freedom in terms of belief. Accounts of 'epistemic freedom' from David Velleman, James Joyce and Jenann Ismael appeal to our justification to form beliefs 'unconstrained' by evidence. Yet, I will argue, these accounts are susceptible to counterexamples and turn out to rely on a primitive ability to believe at will---one that makes the appeal to justification redundant. J. G. Fichte's Idealist account of freedom, based in a primitive activity of the 'I', nicely illustrates the kind of freedom these accounts rely on. In chapter 4 I develop the epistemic model of deliberation into a deliberative account of causation. I argue that A is a type-level cause of B if and only if an agent deciding on a state of affairs of type A in 'proper deliberation', for the sake of a state of affairs of type B would be good evidence of a state of affairs of type B obtaining. This biconditional explains why we should care about causal relations---they direct us to good decisions. But existing accounts of causation don't adequately explain why causation matters. James Woodward's interventionist account explicates 'control' and 'causation' in the very same terms---and so can't appeal to a relation between them to explain why we should care about causal relations. David Lewis' reductive account relies on standards for evaluating counterfactuals, but doesn't motivate them or explain why a causal relation analysed in these terms should matter. Delivering the right verdicts is not enough. The deliberative account explains why causation matters, by relating causal relations to the evidential relations needed for deliberation. In chapter 5 I use the deliberative account to explain causal asymmetry---why, contingently, causes come before their effects. Following an approach from Huw Price, because deliberation comes prior to decision, deliberation undermines evidential relations towards the past. So an agent's deciding for the sake of the past in proper deliberation won't be appropriate evidence of the past, and backwards causation is not implied. To explain why deliberation comes prior to decision, I appeal to an epistemic asymmetry, one that is explained by statistical-mechanical accounts of causation in non-causal terms. But statistical-mechanical accounts still need the deliberative account to justify why the relations they pick out as causal should matter to us. The deliberative account of causation relates causal relations to the evidential relations of use to deliberating agents. It constrains metaphysical accounts, while revealing their underlying explanatory structure. And it does not rule out explanations of causal asymmetry based in physics, but complements them. Overall this project makes sense of causation by foregrounding its relevance for us.

Mechanics of Biologically Inspired Structures and Flexible Mechanical Metamaterials

Fernandes, Matheus C Harvard University ProQuest Dissertations & Theses 2021 해외박사(DDOD)

In this dissertation, I focus on exploring biologically inspired structures and the mechanics of flexible porous metamaterials by utilizing both experimental and computational methods.For the biologically inspired structures portion of this dissertation, namely chapters 2 and 3, I focus on the architectural details of the glassy skeletal system from the hexactinellid sponge, Euplectella aspergillum. In chapter 2, I show that this sponge's meso-scale skeletal system, consisting of a square-grid-like lattice architecture overlaid with a double set of crossed diagonal bracings, exhibits the highest buckling resistance for a given amount of material when compared to related lattice structures. These findings are further confirmed thorough an evolutionary optimization algorithm, through which I demonstrate that the sponge-inspired lattice geometry occurs near the design space's optimum material distribution.At another level of structural hierarchy, in chapter 3 I show that its complex maze-like organization of helical ridges that surround its main skeletal tube, not only provide additional mechanical reinforcement, but perhaps more significantly, deliver a critical hydrodynamic benefit by effectively suppressing von Karman vortex shedding and reducing fluctuations in lift forcing over a wide range of biologically relevant flow regimes. By comparing the disordered sponge ridge geometry to other more symmetrical strake-based vortex suppression systems commonly employed in engineering contexts ranging from antennas to underwater gas and oil pipelines, I find that the unique maze-like ridge organization of the sponge can completely suppress vortex shedding rather than delaying the shedding to a more downstream location. These findings highlight the sponge ridge design's potential benefit in engineering applications.Lastly, in chapter 4, I utilize similar experimental and computational methods to study the response of porous mechanical metamaterials with well-defined periodicity for their ability to exhibit complex behavior as a result of their non-linear deformation. Although it is well known that buckling-induced planar transformations occur in 2D porous metamaterials, here I explore the emergence of 3D morphologies triggered by mechanical instabilities in an elastomeric block with tilted cylindrical holes. I demonstrate that the 3D deformation of these structures can be leveraged to tune surface properties including friction and light reflection, thus providing a new experimental platform for investigating deformation-dependent dynamics for tribological and optical applications.

Directional, shift-insensitive, complex wavelet transforms with controllable redundancy

Fernandes, Felix Carlos A Rice University 2002 해외박사(DDOD)

Although the Discrete Wavelet Transform (DWT) is a powerful tool for signal and image processing, it has three serious disadvantages. First, the DWT is shift sensitive because input-signal shifts generate unpredictable changes in DWT coefficients. Second, the DWT suffers from poor directionality because DWT coefficients reveal only three spatial orientations. Third, DWT analysis lacks the phase information that accurately describes non-stationary signal behavior. To overcome these disadvantages, we introduce the notion of projection-based complex wavelet transforms. These two-stage, projection-based complex wavelet transforms consist of a projection onto a complex function space followed by a DWT of the complex projection. Unlike other popular transforms that also mitigate DWT shortcomings, the decou pled implementation of our transforms has two important advantages. First, the controllable redundancy of the projection stage offers a balance between degree of shift sensitivity and transform redundancy. This allows us to create a directional, non-redundant, complex wavelet transform with potential benefits for image coding systems. To the best of our knowledge, no other complex wavelet transform is simultaneously directional and non-redundant. The second advantage of our approach is the flexibility to use any DWT in the transform implementation. We exploit this flexibility to create the Complex Double-density DWT (CDDWT): a shift-insensitive, directional, complex wavelet transform with a low redundancy of <math> <f> <fr><nu>3^m-1</nu><de>2^m-1</de></fr></f> </math> in <italic>m</italic> dimensions. To the best of our knowledge, no other transform achieves all these properties at a lower redundancy. Besides the mitigation of DWT shortcomings, our transforms have unique properties that will potentially benefit a variety of signal processing applications. As an example, we demonstrate that our projection-based complex wavelet transforms achieve state-of-the-art results in a seismic signal-processing application.

Measuring the seeds of thermal ion outflow

Fernandes, Philip A Dartmouth College 2015 해외박사(DDOD)

The ionosphere is the primary source for heavy ions which are ubiquitous in the terrestrial magnetosphere. Low-altitude energization in the auroral ionosphere results in bulk heating and transverse acceleration of ions, which begin to upwell and/or be accelerated upward by the mirror force, starting upflow and leading to the outflow process. The details of the processes that seed ion outflow at low altitudes are difficult to measure in situ and thus remain an open question. We examine the observational parameter regime in which ion upflow/outflow initiates. Emphasis is placed on making measurements of the thermal ion kinetic distribution function, allowing for accounting of processes which affect in situ plasma measurements. We consider an electrostatic analyzer (ESA) instrument capable of making the measurements necessary to quantify the roles of various heating mechanisms in initiating ion upflow in the low-altitude auroral ionosphere. We present the difficulties associated with making these measurements and identify instrument design choices that mitigate some of these measurement challenges. Analysis of ESA measurements of the thermal ion distribution function taken on the MICA auroral sounding rocket is presented. Using a Maxwellian model to replicate possible measured spectra, we calculate integrated parameters from the model and compare with equivalent parameters calculated from the in situ data. Through Liouville's theorem and the thin-sheath approximation we couple the measured and forward-modeled parameters such that measurements inside the sheath provide information about the state of the plasma outside the sheath. Throughout the MICA flight, ion upflow is observed and attributed to ambipolar electric fields and/or ion-neutral interactions. Late in the flight we observe quasi-static frictional process driving the ion temperature. Early in the flight we observe ion heating weakly correlated with ELF wave activity; our analysis suggests we must consider transverse heating by wave-particle interactions. The low-altitude observations of the MICA case study serve to inform future ionospheric modeling and simulations of, specifically, (a) the need to consider heating by wave-particle interactions at altitudes lower than previously considered viable, and (b) the occurrence of structured and localized upflows/downflows on a Type 2 field line before/below associated higher altitude heating processes.

Improving direct solar radiation in complex building envelopes with a computational genetic algorithm

Fernandes, Jose Maria Veiga University of California, Los Angeles 2007 해외박사(DDOD)

This thesis addresses the issue of relating the shape of building envelopes to solar positioning and direct solar radiation. Existing strategies for maximizing solar gains assume that most building surfaces are flat. By examining contemporary architecture, and the computer modeling tools utilized to produce it, a trend towards complex building forms beyond the simply planar emerges. The presented research outlines a method of applying computer genetic algorithms for improving direct solar radiation intake of complex non-planar surfaces. Experiments performing specific searches for optimal forms with improved direct solar radiation performance establish a relationship between surface shape and solar position as a function of the intensity of direct radiation throughout the year. A modeling tool was developed that allows for the parametric manipulation of surfaces for better solar performance. Using known techniques for solar positioning and for calculating clear sky direct radiation a method was developed to measure solar performance of Non-Uniform Rational BSpline Surfaces (NURBS). Using the developed surface rating method experiments were performed to determine the relationship between surface morphology, surface area, and the direct solar radiation received according to the movement of the sun. To this end a computational Genetic Algorithm (GA) is utilized as a search method to find better performing surfaces. Conclusions are drawn as to the geometric relationship between the developed surfaces and the positioning and direct radiation intensity of the sun at various hours, days, months, and seasons. The result is a prototype plug-in tool with which designers can select parameters to improve the solar gain performance of surface designs. The availability of a plug-in tool that is embedded inside commonly utilized modeling software is of significance for designers who seek to develop early-stage shapes that are energy efficient. This method is geared at designers modeling shapes that help in the reduction of energy consumption. Conclusions are drawn as to the new ability the tool provides and new directions are suggested for continuing research and development.

Moving toward Evidence-Based Practice: A Research Utilization Capacity Building Program

Fernandes, Angeline Boston University ProQuest Dissertations & Theses 2022 해외박사(DDOD)

Occupational therapy practitioners (OTPs) are reporting low levels of research application in everyday practice, causing a low frequency of evidence-based practice (EBP) implementation (Krueger et al., 2020; Myers, 2019a). A review of the literature demonstrates that individual level factors, such as lack of knowledge, skill, time, and resources for research use, coupled with organizational factors, such as low priority, support, and expectation for EBP, act as barriers to EBP (Wang et al., 2019). This doctoral project aims to build the capacity for research use at both the practitioner and the organization levels through an evidence-based multifaceted intervention program. It will impact the knowledge and skill for understanding and applying research evidence in practice and the frequency of research use in daily practice among school-based occupational therapy practitioners (Sb-OTPs), as well as the organization’s resources, priorities, and environment to support EBP. A mixed-methods design will be used, with a convenience sample of nineteen Sb-OTPs employed at a therapy agency that provides services through contract positions to local school districts. The program consists of four main components of education, provision of resources, working in groups, and organizational supports. The Knowledge-To-Action (KTA) framework (Graham et al., 2009) provides a context-focused iterative process to the program design, from problem identification to sustainability. Continual involvement of all stakeholders, assessment of barriers to tailor the intervention, and adaptation of the knowledge for use in the practice context are KTA-based core program features. The education component is informed by Social Cognitive Theory (SCT) (Bandura, 1986), brain-based learning strategies (Willis, 2006; Yee & Boyd, 2018), and literature supporting blended learning and digital health education formats (Brown et al., 2020; Hew & Lo, 2018; Liu et al., 2016). The program description, implementation, research evaluation plan, and program funding and dissemination are described in detail.