Neste trabalho estudou-se o comportamento dos chumbadores grauteados, usados em ligações viga-pilar parcialmente resistentes a momento fletor. O foco da pesquisa foi a análise teórica e experimental do mecanismo resistente do chumbador inclinado. O programa experimental englobou 15 modelos, sendo que as variáveis analisados foram: a) diâmetros dos chumbadores, de 16 mm, 20 mm e 25 mm; b) inclinações dos chumbadores, de 0º (chumbador normal à interface), 45º e 60º; c) resistência à compressão do concreto adjacente ao chumbador, sendo usado concreto das classes C35 e C50; d) aplicação de força de compressão normal à interface. Os resultados experimentais indicaram aumentos significativos tanto na capacidade última quanto na rigidez a cisalhamento do chumbador. Foram realizadas simulações numéricas, onde foi verificada a sensibilidade dos resultados aos parâmetros inerentes à interface concreto - almofada de apoio, sendo desenvolvidas expressões para estimar tais parâmetros. Com base na análise experimental e em análises numéricas, foram propostos modelos analíticos que conseguiram representar de forma satisfatória a influência da inclinação e demais parâmetros analisados no mecanismo resistente do chumbador. / This research deals with the behavior of grouted dowels, used in partial moment resistant beam-to-column connections. The focus of the research was the theoretical and experimental analysis of dowels resistant mechanism. The experimental program include 15 models, and its variables analyzed were: a) the dowel diameter of 16 mm, 20 mm and 25 mm; b) the dowel inclination of 0° (dowels perpendicular to the interface), 45° and 60°; c) compressive strength of concrete adjacent to the dowels of classes C35 and C50, d) application of compression load, normal to the interface. Experimental results indicated significant increases in ultimate capacity and the shear stiffness of the dowels. Numerical simulations were carried out which identified the sensitivity of results to the parameters of the interface concrete bearing pad, and developed expressions to estimate such parameters are given. Based on experimental and numerical analysis analytical models have been proposed that could adequately represent the influence of inclination and other parameters in the mechanism resistant dowels.

[pt] Tradicionalmente, o projeto de pórticos em estruturas de aço assume que as ligações viga-coluna são rígidas ou flexíveis. As ligações rígidas, onde não ocorre nenhuma rotação entre os membros conectados, transferem não só momento fletor, mas também força cortante e força normal. Por outro lado, as ligações flexíveis são caracterizadas pela liberdade de rotação entre os membros conectados impedindo a transmissão de momento fletor. Desconsiderando- se estes fatos, sabe-se que a grande maioria das ligações não possuem este comportamento idealizado. De fato, a maioria das ligações transfere algum momento fletor com um nível de rotação associado. Estas ligações são chamadas semi-rígidas e seu dimensionamento deve ser executado de acordo com este comportamento estrutural real. Porém, algumas ligações viga-coluna estão sujeitas a uma combinação de momento fletor e esforço axial. O nível de esforço axial pode ser significativo, principalmente em ligações de pórticos metálicos com vigas inclinadas, em pórticos não-contraventados ou em pórticos com pavimentos incompletos. As normas atuais de dimensionamento de ligações estruturais em aço não consideram a presença de esforço axial (tração e/ou compressão) nas ligações. Uma limitação empírica de 5 por cento da resistência plástica da viga é a única condição imposta no Eurocode 3. O objetivo deste trabalho é descrever alguns resultados experimentais e numéricos para estender a filosofia do método das componentes para ligações com ações combinadas de momento fletor e esforço axial. Para se cumprir este objetivo, quinze ensaios foram realizados e um modelo mecânico é apresentado para ser usado na avaliação das propriedades da ligação: resistência à flexão, rigidez inicial e capacidade de rotação. / [en] Traditionally, the steel portal frame design assumes that beam-to-column joints are rigid or pinned. Rigid joints, where no relative rotations occur between the connected members, transfer not only substantial bending moments, but also shear and axial forces. On the other extreme, pinned joints, are characterised by almost free rotation movement between the connected elements that prevents the transmission of bending moments. Despite these facts, it is largely recognised that the great majority of joints does not exhibit such idealised behaviour. In fact, many joints transfer some bending moments associated with rotations. These joints are called semi-rigid, and their design should be performed according to their real structural behaviour. However, some steel beam-to-column joints are often subjected to a combination of bending and axial forces. The level of axial forces in the joint may be significant, typical of pitched-roof portal frames, sway frames or frames with incomplete floors. Current standard for steel joints do not take into account the presence of axial forces (tension and/or compression) in the joints. A single empirical limitation of 5 percent of the beam s plastic axial capacity is the only enforced provision in Annex J of Eurocode 3. The objective of the present work is to describe some experimental and numerical results to extend the philosophy of the component method to deal with the combined action of bending and axial forces. To fulfil this objective a set of sixteen specimens were performed and a mechanical model was developed to be used in the evaluation of the joint properties: bending moment resistance, initial stiffness and rotation capacity.

O presente trabalho tem por objetivo desenvolver uma formulação numérica baseada em Análise Isogeométrica para o estudo de problemas de interação fluido-estrutura (IFE) em aplicações envolvendo corpos rígidos submersos, onde escoamentos incompressíveis de fluidos Newtonianos com superfície livre são considerados. Propõe-se o emprego da Análise Isogeométrica por permitir a unificação entre os procedimentos de pré-processamento e análise, melhorando assim as condições de continuidade das funções de base empregadas tanto na discretização espacial do problema como na aproximação das variáveis do sistema de equações. O sistema de equações fundamentais do escoamento é formado pelas equações de Navier-Stokes e pela equação da conservação de massa, descrita segundo a hipótese de pseudo-compressibilidade, em uma formulação cinemática ALE (Arbitrary Lagrangean- Eulerian). A consideração da superfície livre no escoamento se dá tratando o fluido como um meio bifásico, através do método Level Set. O corpo rígido apresenta não linearidade na rotação e restrições representadas por vínculos elásticos e amortecedores viscosos, sendo a equação de equilíbrio dinâmico resolvida através do método de Newmark. O esquema de acoplamento sólido-fluido adotado é o particionado convencional, que impõe condições de compatibilidade cinemáticas e de equilíbrio sobre a interface sólido-fluido, analisando ambos os meios de maneira sequencial. A discretização das equações governantes é realizada através do esquema explícito de dois passos de Taylor-Galerkin, aplicado no contexto da Análise Isogeométrica. Por fim, são analisados alguns problemas da Dinâmica de Fluidos Computacional, de onde se concluiu que os resultados obtidos são bastante consistentes com os fenômenos envolvidos, com as ferramentas exclusivas da Análise Isogeométrica, como o refinamento k, melhorando a convergência dos resultados. Para escoamentos bifásicos, verificou-se que o método Level Set obteve resultados bastante promissores apresentando, entretanto, uma dissipação numérica excessiva. Propõe-se, para estudos futuros, a elaboração de esquemas numéricos que conservem melhor o volume da fase líquida do escoamento. / The present work aims to development of a numerical formulation based on Isogeometric Analysis for the study of Fluid-Structure Interaction problems in applications involving rigid bodies submerged, considering incompressible Newtonian flows with free surface. The use of the Isogeometric Analysis allows unification between the preprocessing and analysis steps, improving then the continuity of the base functions employed, both in the spatial discretization and approximation of the variables in the system of equations. The fundamental flow equations are formed by the Navier-Stokes and the mass conservation, described by de pseudo-compressibility hypothesis, in an ALE (Arbitrary Lagrangean-Eulerian) kinematic formulation. The free surface consideration of the flow is handled treating the fluid like a two- phase medium, using the Level Set method. The rigid body considers nonlinearity in rotation, and restrictions represented by elastic springs and viscous dampers, with the dynamic equilibrium equation being resolved using the Newmark’s method. The solid-fluid coupling scheme is the conventional partitioned, which imposes kinematics and equilibrium compatibility conditions on the solid-fluid interface, analyzing both mediums in a sequential manner. The governing equations are discretized using the explicit two step Taylor-Galerkin method, applied in an Isogeometric Analisys context. Finally, some Computational Fluid Dinamics problems are analysed, from which it was concluded that the results obtained are quite consistent with phenomena involved, with the unique tools of Isogeometric Analysis, such as k-refinement, improving the convergence of the results. For biphasic flows, it was verified that the Level Set method obtained very promising results, presenting, however, an excessive numerical dissipation. For future studies, it is proposed the elaboration of numerical schemes that better preserve the volume of the liquid phase of the flow.

Neste trabalho estudam-se os efeitos dependentes do tempo em vigas de concreto pré-moldado, protendidas ou não, com concretagem posterior formando um conjunto de seção composta com lajes alveolares, usual em pavimentos de edifícios, e ocasionando um estabelecimento da continuidade com ligação semi-rígida. Os esforços de restrição causados pelos efeitos de retração e fluência dos diversos concretos envolvidos e possível relaxação das cordoalhas de protensão nos extremos dessas vigas acarretam uma redistribuição de esforços função do tempo, causando deslocamentos axiais e rotações no elemento. Esta análise é feita utilizando a programação em elementos finitos CONS, própria para análise não-linear de estruturas em concreto construídas evolutivamente, aplicada a modelos representativos. O programa CONS apresentou bastante precisão na avaliação dos efeitos do tempo respaldado por estudos experimentais. Com base no estudo de dois modelos representativos de concreto pré-moldado foi observado que: a) os momentos de restrição acarretaram modificações sensíveis na região da ligação influenciando na fissuração da peça e no valor final de momento fletor, com alterações de até 80% para a viga de concreto armado, e inversão do sinal para a viga de concreto protendido; b) em comparação com as demais, as deformações axiais tiveram uma maior influência dos efeitos do tempo chegando a acréscimos posteriores à imposição do último carregamento de até 90% para a viga de concreto protendido; c) a retração diferencial entre concretos de idades distintas originou tensões de tração consideráveis em especial na região da interface. / In this research, time-dependent effects in precast concrete beams, prestressed or not, with posterior concreting resulting in a structure of a composite cross section with hollow core slabs, usual in buildings floors, and made continuous with semi-rigid connection are studied. The restraint stresses caused by the effects of the shrinkage and creep of the various concretes involved and possible relaxation of the prestressed tendons in the extremities of these beams imply in a rearrangement of time-dependent stresses, leading to axial deflection and rotations in the element. This analysis is made using the finite element based program CONS for non-linear analysis of progressively assembled concrete structures, applied in representative samples. CONS presented great accuracy in the evaluation of time effects supported by experimental studies. Based on a study of two precast concrete structures examples, it was observed that: a) the restraint stresses lead to sensible modifications in the connection, influencing on the cracking of the piece and in the final bending moment with changes of 80% for the reinforced concrete sample, and sign inversion for the prestressed one; b) In comparison among the others, the axial deformation had a greater influence in time effects in the samples analyzed, with increases after the last load of 90% in the prestressed example; c) the differential shrinkage between concretes of different ages has generated great tensile stresses, specially on the interface.

Este trabalho parte de um acervo pré-existente de provas de carga em placa (segundo os procedimentos ABNT-NBR-6489 e ASTM-D-1196) em solos da Formação Guabirotuba, importante unidade geológica da região metropolitana de Curitiba. O objetivo do trabalho é favorecer o entendimento destes solos no que diz respeito à sua competência como subleito para pavimentos industriais rígidos. É realizada uma revisão sobre modelos de fundação de pavimento, aspectos geológicos e geotécnicos da Formação Guabirotuba, e métodos de determinação do coeficiente de recalque. A análise baseia-se no coeficiente de recalque \"k\" obtido em trinta e duas provas de carga em placa e utiliza uma classificação prática dos solos, quanto ao seu nível de intemperismo: argilas cinzas \"inalteradas\", argilas vermelhas \"laterizadas\" e argilas variegadas \"intemperizadas\", as quais mostram valores decrescentes de coeficiente de recalque, nessa ordem. Notou-se que algumas correlações existentes na literatura permitiram obter razoáveis previsões do coeficiente de recalque, como aquelas baseadas em valores de SPT e de CBR. Os valores de coeficiente de recalque medidos para estes solos mostram-se superiores àqueles sugeridos por tabelas práticas. Devido à variabilidade de resultados encontrada e à influência do subleito no desempenho final do sistema de fundação, fica evidenciada a importância da realização de provas de carga em placa para obtenção dos parâmetros de dimensionamento de pavimentos industriais rígidos. / The present work employs a data base of plate load tests (performed according the ABNT-NBR-6489 and ASTM-D-1196 procedures) in soils of the Guabirotuba Formation, important geological unit of Curitiba metropolitan region. The purpose of the work is the improving of the knowledge of these soils related to their behavior as subgrade for rigid industrial pavements. It is provided a revision about pavements foundation models, geological and geotechnical aspects of the Guabirotuba Formation and methods of the determination of the modulus of subgrade reaction. The analysis is based on the modulus of subgrade reaction \"k\" from 32 plate loading tests and uses a practical classification of the soils, according to their weathering level: intact gray clays, lateritic red clays and weathered variagate clays that showed a derease of the modulus in this order. Some correlations were found to predict fair values of \"k\", such as those based on SPT and on DCP. It was also noticed that the values of the modulus of subgrade reaction obtained are higher than the usual recommendations of the literature. The variability and the influence of the subgrade in the final performance of the pavaments make evident the importance of the plate load tests for obtaining reliable design parameters.

by Chi-Min Pang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 110-[115]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Range Images --- p.1 / Chapter 1.2 --- Rigid Body Model --- p.3 / Chapter 1.3 --- Motivation --- p.4 / Chapter 1.4 --- Thesis Outline --- p.6 / Chapter 2 --- Object Recognition by Relaxation Processes --- p.7 / Chapter 2.1 --- An Overview of Probabilistic Relaxation Labelling --- p.8 / Chapter 2.2 --- Formulation of Model-matching Problem Solvable by Probabilistic Relaxation --- p.10 / Chapter 2.2.1 --- Compatibility Coefficient --- p.11 / Chapter 2.2.2 --- Match Score --- p.13 / Chapter 2.2.3 --- Iterative Algorithm --- p.14 / Chapter 2.2.4 --- A Probabilistic Concurrent Matching Scheme --- p.15 / Chapter 2.3 --- Formulation of Model-merging Problem Solvable by Fuzzy Relaxation --- p.17 / Chapter 2.3.1 --- Updating Mechanism --- p.17 / Chapter 2.3.2 --- Iterative Algorithm --- p.19 / Chapter 2.3.3 --- Merging Sub-Rigid Body Models --- p.20 / Chapter 2.4 --- Simulation Results --- p.21 / Chapter 2.4.1 --- Experiments in Model-matching Using Probabilistic Relaxation --- p.22 / Chapter 2.4.2 --- Experiments in Model-matching Using Probabilistic Concur- rent Matching Scheme --- p.26 / Chapter 2.4.3 --- Experiments in Model-merging Using Fuzzy Relaxation --- p.33 / Chapter 2.5 --- Summary --- p.36 / Chapter 3 --- Object Recognition by Hopfield Network --- p.37 / Chapter 3.1 --- An Overview of Hopfield Network --- p.38 / Chapter 3.2 --- Model-matching Problem Solved by Hopfield Network --- p.41 / Chapter 3.2.1 --- Representation of the Solution --- p.41 / Chapter 3.2.2 --- Energy Function --- p.42 / Chapter 3.2.3 --- Equations of Motion --- p.46 / Chapter 3.2.4 --- Interpretation of Solution --- p.49 / Chapter 3.2.5 --- Convergence of the Hopfield Network --- p.50 / Chapter 3.2.6 --- Iterative Algorithm --- p.51 / Chapter 3.3 --- Estimation of Distance Threshold Value --- p.53 / Chapter 3.4 --- Cooperative Concurrent Matching Scheme --- p.55 / Chapter 3.4.1 --- Scheme for Recognizing a Single Object --- p.56 / Chapter 3.4.2 --- Scheme for Recognizing Multiple Objects --- p.60 / Chapter 3.5 --- Simulation Results --- p.60 / Chapter 3.5.1 --- Experiments in the Model-matching Problem Using a Hopfield Network --- p.61 / Chapter 3.5.2 --- Experiments in Model-matching Problem Using Cooperative Concurrent Matching --- p.69 / Chapter 3.5.3 --- Experiments in Model-merging Problem Using Hopfield Network --- p.77 / Chapter 3.6 --- Summary --- p.80 / Chapter 4 --- Genetic Generation of Weighting Parameters for Hopfield Network --- p.83 / Chapter 4.1 --- An Overview of Genetic Algorithms --- p.84 / Chapter 4.2 --- Determination of Weighting Parameters for Hopfield Network --- p.86 / Chapter 4.2.1 --- Chromosomal Representation --- p.87 / Chapter 4.2.2 --- Initial Population --- p.88 / Chapter 4.2.3 --- Evaluation Function --- p.88 / Chapter 4.2.4 --- Genetic Operators --- p.89 / Chapter 4.2.5 --- Control Parameters --- p.91 / Chapter 4.2.6 --- Iterative Algorithm --- p.94 / Chapter 4.3 --- Simulation Results --- p.95 / Chapter 4.3.1 --- Experiments in Model-matching Problem using Hopfield Net- work with Genetic Generated Parameters --- p.95 / Chapter 4.3.2 --- Experiments in Model-merging Problem Using Hopfield Network --- p.101 / Chapter 4.4 --- Summary --- p.104 / Chapter 5 --- Conclusions --- p.106 / Chapter 5.1 --- Conclusions --- p.106 / Chapter 5.2 --- Suggestions for Future Research --- p.109 / Bibliography --- p.110 / Chapter A --- Proof of Convergence of Fuzzy Relaxation Process --- p.116

Made available in DSpace on 2017-07-10T14:38:31Z (GMT). No. of bitstreams: 1 RENNAN_MEIRA.pdf: 1775699 bytes, checksum: c942a970d534e03e29d864cafff3d525 (MD5) Previous issue date: 2016-04-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of green manure with different native species stands out among the alternative techniques for restoring them. This coexistence (green manure + forest species) may be influenced by the release of chemicals in the environment, a phenomenon known as allelopathy. Thus, the present work was divided in two sections made in the form of an article. In the first chapter, the objective of this study was to evaluate the allelopathic activity of aqueous extract of green manure Cajanus cajan (pigeon pea) by oxidative stress analysis of tomato, under laboratory conditions. As a result, there has been increased activity of superoxide dismutase, catalase and peroxidadase in minor proportions, however 10% of the enzymes were not effective in detoxification of tissues resulting in increased lipid peroxidation during germination, showing inhibitory effect, as well as in seedlings, resulting in lower root length and shoot in the proportion 10%. Therefore, the aqueous extract of pigeonpea has allelopathic activity, inhibiting the antioxidative system, causing damage membrane, delaying the germination of seeds and reducing the length of the root tomato seedlings. In the second chapter, the objective was to evaluate the allelopathic effect of green manure C. cajan on the pioneer species Bauhinia forficata (pata-de-vaca) and early secondary P. rigida (angico-vermelho), and to evaluate the allelopathic influence of the species pioneer of the early secondary species. The aqueous extract of C. cajan had a positive effect, especially in smaller proportions (2.5 and 5%) for the seeds and seedlings of B. forficata, as for P. rigida showed inhibitory effect in the highest proportions (7.5 and 10%). The aqueous extract of B. forficata on secondary P. rigid, delayed germination and decreased the number of germinated seeds per day, besides influencing seedling growth decreasing the average length of roots and shoots in the proportion 10%. Thus, the green manure C. cajan, has beneficial allelopathic effects on germination and early development of pioneer species B. forficata, but the same is not true of the initial P. rigida secondary species. Furthermore, the pioneering has inhibitory effects on P. rigida, with increasing proportion of the extract, during germination and early development / O uso da adubação verde com diferentes espécies florestais nativas, destaca-se entre as técnicas alternativas para restauração das mesmas. Essa convivência (adubação verde + espécies florestais) pode ser influenciada pela liberação de compostos químicos no ambiente, fenômeno conhecido como alelopatia. Deste modo, a presente dissertação foi dividida em dois capítulos elaborados na forma de artigo. No primeiro capítulo, o objetivo do trabalho foi avaliar a atividade alelopática do extrato aquoso do adubo verde Cajanus Cajan (feijão guandu) por meio da análise do estresse oxidativo sobre o tomate, em condições laboratoriais. Como resultado, houve aumento da atividade das enzimas superóxido-dismutase, catalase e peroxidadase nas menores proporções, no entanto a 10% as enzimas não foram eficientes na detoxificação dos tecidos resultando em maior peroxidação lipídica, durante a germinação, evidenciando efeito inibitório, assim como nas plântulas, resultando em menores comprimentos de raiz e parte aérea na proporção 10%. Portanto, o extrato aquoso de feijão guandu apresenta atividade alelopática, inibindo o sistema antioxidativo, ocasionando danos de membrana, retardando a germinação das sementes e diminuindo o comprimento radicular das plântulas de tomate. No segundo capítulo, o objetivo foi avaliar o efeito alelopático do adubo verde C. cajan, sobre a espécie pioneira Bauhinia forficata (pata-de-vaca) e secundária inicial Parapiptadenia rigida (angico-vermelho), além de avaliar a influência alelopática da espécie pioneira sobre a espécie secundária inicial. O extrato aquoso de C. cajan exerceu efeito positivo, principalmente, nas menores proporções (2,5 e 5%) para as sementes e plântulas de B. forficata, já para P. rigida apresentou efeito inibitório nas maiores proporções (7,5 e 10%). O extrato aquoso de B. forficata sobre a secundária P. rígida, atrasou a germinação e diminuiu o número de sementes germinadas por dia, além de influenciar no crescimento das plântulas diminuindo o comprimento médio da raiz e parte aérea, na proporção 10%. Desse modo, o adubo verde C. cajan, apresenta efeitos alelopáticos benéficos sobre a germinação e desenvolvimento inicial da espécie pioneira B. forficata, porém o mesmo não acontece sobre a espécie secundária inicial P. rigida. Além disso, a pioneira apresenta efeitos inibitórios sobre P. rigida, conforme o aumento da proporção do extrato, tanto na germinação quanto no desenvolvimento inicial.

Proteins are involved in numerous functions in the human body, including chemical transport, molecular recognition, and catalysis. To perform their function most proteins must adopt a specific structure (often referred to as the folded structure). A microscopic description of folding is an important prerequisite for elucidating the underlying basis of protein misfolding and rational drug design. However, protein folding occurs on heterogeneous length and time scales, presenting a grand challenge to both experiments and simulations. In computer simulations, challenges are generally mitigated by adopting coarse-grained descriptions of the physical environment, employing enhanced sampling strategies, and improving computing code and hardware. While significant advances have been made in these areas, for numerous systems a large spatiotemporal gap between experiment and simulations still exists, due to the limited time and length scales achieved by simulation, and the inability of many experimental techniques to probe fast motions and short distances. In this thesis, kinetic transition networks (KTNs) are constructed for various protein folding systems, via approaches based on the potential energy landscape (PEL) framework. By applying geometry optimisation techniques, the PEL is discretised into stationary points (i.e.~low-energy minima and the transition states that connect them). Essentially, minima characterise the low-lying regions of the PEL (thermodynamics) and transition states encode the motion between these regions (dynamics). Principles from statistical mechanics and unimolecular rate theory may then be employed to derive free energy surfaces and folding rates, respectively, from the KTN. Furthermore, the PEL framework can take advantage of parallel and distributed computing, since stationary points from separate simulations can be easily integrated into one KTN. Moreover, the use of geometry optimisation facilitates greater conformational sampling than conventional techniques based on molecular dynamics. Accordingly, this framework presents an appealing means of probing complex processes, such as protein folding. In this dissertation, we demonstrate the application of state-of-the-art theory, combining PEL analysis and KTNs to three diverse protein systems. First, to improve the efficiency of protein folding simulations, the intrinsic rigidity of proteins is exploited by implementing a local rigid body (LRB) approach. The LRB approach effectively integrates out irrelevant degrees of freedom from the geometry optimisation procedure and further accelerates conformational sampling. The effects of this approach on the underlying PEL are analysed in a systematic fashion for a model protein (tryptophan zipper\,1). We demonstrate that conservative local rigidification can reproduce the thermodynamic and dynamic properties for the model protein. Next, the PEL framework is employed to model large-scale conformational changes in proteins, which have conventionally been difficult to probe in silico. Methods based on geometry optimisation have proved useful in overcoming the broken ergodicity issue, which is associated with proteins that switch morphology. The latest PEL-based approaches are utilised to investigate the most extreme case of fold-switching found in the literature:~the α-helical hairpin to β-barrel transition of the C-terminal domain of RfaH, a bacterial transcription factor. PEL techniques are employed to construct the free energy landscape (FEL) for the refolding process and to discover mechanistic details of the transition at an atomistic level. The final part of the thesis focuses on modelling intrinsically disordered proteins (IDPs). Due to their inherent structural plasticity, IDPs are generally difficult to characterise, both experimentally and via simulations. An approach for studying IDPs within the PEL framework is implemented and tested with various contemporary potential energy functions. The cytoplasmic tail of the human cluster of differentiation 4 (CD4), implicated in HIV-1 infection, is characterised. Metastable states identified on the FEL help to unify, and are consistent with, several earlier predictions.

The Bistable Aerial Platform (BAP) has been developed in order to further enlarge the repertoire of devices available at the microscale. This novel device functions as a switch in that its platform can lock in two positions, up or down. Herein, it will be examined and explained, but a true understanding of its workings requires a better understanding of its compliant constituent parts. The Helico-Kinematic Platform (HKP), which serves as an actuator for the BAP, is currently under investigation by another researcher and will be merely touched upon here. The focus, therefore, will rest on the analysis of the Quadrantal Bistable Mechanism (QBM), the principle component of the BAP. A preliminary pseudo-rigid-body model, an aid for the understanding of compliant mechanisms, will also be examined for the QBM. The models developed for these two devices, the HKP and QBM, can later be combined to form a full model of the Bistable Aerial Platform.

視覺追蹤(visual tracking)一直是傳統電腦視覺研究中相當重要的議題，許多電腦視覺的應用都需要結合視覺追蹤的幫助才能實現。近年來擴增實境(augmented reality)能快速成功的發展，均有賴於視覺追蹤技術上之精進。擴增實境採用視覺追蹤的技術，可將虛擬的物件呈現在被追蹤的物體(真實場景)上，進而達成所需之應用。 由於在視覺追蹤上，被追蹤之物體易受外在環境因素影響，例如位移、旋轉、縮放、光照改變等，影響追蹤結果之精確度。本研究中，我們設計了一套全新的圖形標記方法作為視覺追蹤之參考點，能降低位移、旋轉與光照改變所造成追蹤結果的誤差，也能在複雜的背景中定位出標記圖形的正確位置，提高視覺追蹤的精確度。同時我們使用立體視覺追蹤物體，將過去只使用單一攝影機於二維影像資訊的追蹤問題，提升至使用三維空間的幾何資訊來做追蹤。然後透過剛體(rigid)特性找出旋轉量、位移量相同的物件，並且結合一致性隨機取樣(random sample consensus)之技巧以估測最佳的剛體物件運動模型，達到強健性追蹤的目的。 另外，我們可由使用者提供之影片資訊中擷取特定資料，透過建模技術將所產生之虛擬物件呈現於使用者介面(或被追蹤之物體)上，並藉由這些虛擬物件，提供真實世界外之資訊，達成導覽指引(或擴增實境)的效果。 實驗結果顯示，我們的方法具有辨識時間快、抗光照變化強、定位準確度高的特性，適合於擴增實境應用，同時我們設計的標記圖形尺寸小，方便適用於導覽指引等應用。 / Visual tracking is one of the most important research topics in traditional computer vision. Many computer vision applications can not be realized without the integration of visual tracking techniques. The fast growing of augmented reality in recent years relied on the improvement of visual tracking technologies. External environment such as object displacement, rotation, and scaling as well as illumination conditions will always influence the accuracy of visual tracking. In this thesis, we designed a set of markers that can reduce the errors induced by the illumination condition changes as well as that by the object displacement, rotation, and scaling. It can also correctly position the markers in complicated background to increase the tracking accuracy. Instead of using single camera tracking in 2D spaces, we used stereo vision techniques to track the objects in 3D spaces. We also used the properties of rigid objects and search for the objects with the same amount of rotation and displacement. Together with the techniques of random sample consensus, we can estimate the best rigid object motion model and achieve tracking robustness. Moreover, from the user supplied video, we can capture particular information and then generate the virtual objects that can be displaced on the user’s device (or on the tracked objects). Using these techniques we can either achieve navigation or guidance in real world or achieve augmented reality as we expected. The experimental results show that our mechanism has the characteristics of fast recognition, accurate positioning, and resisting to illumination changes that are suitable for augmented reality. Also, the size of the markers we designed is very small and good for augmented reality application.