A new approach to the absolute measurement of two-dimensional optical path differences is presented in this thesis. The method, which incorporates a white light interferometer and a hyperspectral imaging system, is referred to as Hyperspectral Interferometry. A prototype of the Hyperspectral Interferometry (HSI) system has been designed, constructed and tested for two types of measurement: for surface profilometry and for depth-resolved displacement measurement, both of which have been implemented so as to achieve single shot data acquisition. The prototype has been shown to be capable of performing a single-shot 3-D shape measurement of an optically-flat step-height sample, with less than 5% difference from the result obtained by a standard optical (microscope) based method. The HSI prototype has been demonstrated to be able to perform single-shot measurement with an unambiguous 352 (m depth range and a rms measurement error of around 80 nm. The prototype has also been tested to perform measurements on optically rough surfaces. The rms error of these measurements was found to increase to around 4× that of the smooth surface. For the depth-resolved displacement field measurements, an experimental setup was designed and constructed in which a weakly-scattering sample underwent simple compression with a PZT actuator. Depth-resolved displacement fields were reconstructed from pairs of hyperspectral interferograms. However, the experimental results did not show the expected result of linear phase variation with depth. Analysis of several possible causes has been carried out with the most plausible reasons being excessive scattering particle density inside the sample and the possibility of insignificant deformation of the sample due to insufficient physical contact between the transducer and the sample.

Structured light illumination (SLI) is the process of projecting a series of light striped patterns such that, when viewed at an angle, a digital camera can reconstruct a 3-D model of a target object's surface. But by relying on a series of time multiplexed patterns, SLI is not typically associated with video applications. For this purpose of acquiring 3-D video, a common SLI technique is to drive the projector/camera pair at very high frame rates such that any object's motion is small over the pattern set. But at these high frame rates, the speed at which the incoming video can be processed becomes an issue. So much so that many video-based SLI systems record camera frames to memory and then apply off-line processing. In order to overcome this processing bottleneck and produce 3-D point clouds in real-time, we present a lookup-table (LUT) based solution that in our experiments, using a 640 by 480 video stream, can generate intermediate phase data at 1063.8 frames per second and full 3-D coordinate point clouds at 228.3 frames per second. These achievements are 25 and 10 times faster than previously reported studies. At the same time, a novel dual-frequency pattern is developed which combines a high-frequency sinusoid component with a unit-frequency sinusoid component, where the high-frequency component is used to generate robust phase information and the unit-frequency component is used to reduce phase unwrapping ambiguities. Finally, we developed a gamma model for SLI, which can correct the non-linear distortion caused by the optical devices. For three-step phase measuring profilometry (PMP), analysis of the root mean squared error of the corrected phase showed a 60х reduction in phase error when the gamma calibration is performed versus 33х reduction without calibration.

Structured Light Illumination (SLI) is the process where spatially varied patterns are projected onto a 3-D surface and based on the distortion by the surface topology, phase information can be calculated and a 3D model constructed. Phase Measuring Profilometry (PMP) is a particular type of SLI that requires three or more patterns temporarily multiplexed. High speed PMP attempts to scan moving objects whose motion is small so as to have little impact on the 3-D model. Given that practically all machine vision cameras and high speed cameras employ a Field Programmable Gate Array (FPGA) interface directly to the image sensors, the opportunity exists to do the processing on camera. This thesis focuses on the design, implementation, testing, and evaluation of a camera-projector system to implement a PMP dual-frequency scheme for 3-D shape measurement on a single FPGA chip. The processor architecture is implemented and tested using the Xilinx Spartan 3 FPGA chip on an Opal Kelly development board. The hardware is described using VHDL and Verilog Hardware Description Languages (HDLs).

Made available in DSpace on 2015-05-14T12:56:05Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2455029 bytes, checksum: 0889fcfcf64d79338e5014d0a4360899 (MD5) Previous issue date: 2009-12-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main effect of the microabrasion in the enamel is significant erosion. However, there is a gap in the literature about validated and reproducible assessment of the depth of erosion in the enamel surface which is originally curve. AIMS: Evaluate depth of erosion and mineral loss of enamel produced by microabrasion technique in original coronary surface of human teeth. METHODS AND MATERIALS: 40 extracted human molars were randomly spited in four groups, with 10 specimens each, in accordance with the microabrasive treatment: AC- 18% hydrochloric acid and pumice, AF 37% phosphoric acid and pumice, OP Opalustre and WRM Whiteness RM. Each specimens had buccal surface´s laterals isolated so that the central area received the microabrasion treatment. After this procedure, transverse slices not demineralized were prepared and submitted to microradiography and analysis in Polarized Light Microscope. One own terminology had created for the morphology of the interface enamel normal-microabrasioned. This served as base to introduction of a profilometry technique with analysis of digital images, in order to get the depth of erosion on microabrasion´s area. The Intraclass Correlation Test was applied to test technique´s reproducibility. The mineral loss and the depth which it happened had analyzed by transverses plotted at equidistant points of the limit enamel normal-microabrasioned. The dates were analyzed with ANOVA test (p < 0.05). RESULTS: The profilometry technique achieved a good reproducibility (Intraclass Correlation Test of 0,9998) and was validated internally. The AC group was the most aggressive, with a greater depth of erosion (110,51 ± 41,21 &#956;m), and a greater mineral loss (13 ± 3 peso %), with significant difference between WRM group (p < 0,05; 9,41± 4,4 peso %) and OP group (p < 0,05; 9,0 ± 3,8 peso %). The OP group, on the other hand, was the less aggressive, with the lowest values in all parameters analyzed, presenting depth of erosion less than AC group (p < 0,0001), WRM group (p < 0,001; 86,24 ± 27,99 &#956;m) and AF group (p < 0,05; 74,46 ± 42,06 &#956;m). The others two groups achieved intermediate results for depth of erosion and mineral loss. The depth of mineral loss was greater than on AF group (31,38 ± 20,30 &#956;m), however, there wasn´t statistical difference between the groups. CONCLUSIONS: Based on own terminology for the interface enamel normalmicroabrasioned and on the implementation of new technique of profilometry, the agents tested showed a significant difference in the depth of erosion, which was consistent with the mineral loss. However, there wasn´t difference in the depth of mineral loss. Furthermore the new technique of profilometry is proposed to fill a gap in the literature, allowing the determination of physical depth of erosion in areas naturally curves of hard biological tissues. / O principal efeito da microabrasão no esmalte dental é uma erosão significativa. Porém, existe uma lacuna na literatura no que concerne à avaliação validada e reprodutível da profundidade de desgaste na superfície dental natural. OBJETIVOS: Avaliar a profundidade de desgaste e a perda mineral do esmalte dentário resultante da técnica de microabrasão na superfície coronária original de dentes humanos. MATERIAIS E MÉTODOS: 40 terceiros molares humanos extraídos foram divididos aleatoriamente em 4 grupos, de 10 espécimes cada, de acordo com o material microabrasivo utilizado: AC - ácido clorídrico a 18% e pedra-pomes, AF - ácido fosfórico a 37% e pedra-pomes, OP - Opalustre® e WRM - Whiteness RM®. Cada elemento teve as laterais da face vestibular protegidas para que apenas a área central fosse exposta aos agentes microabrasivos. Após o procedimento de microabrasão, cortes transversais não desmineralizados foram preparados e submetidos à radiomicrografia e análise em Microscopia de Luz Polarizada. Uma terminologia própria foi formulada para a morfologia da interface esmalte normalmicroabrasionado. Esta serviu de base à introdução de uma Técnica de Perfilometria com Análise de Imagens Digitais, com o intuito de obter a profundidade de desgaste ao longo da área microabrasionada. O teste de correlação intraclasse foi aplicado para testar a reprodutibilidade da técnica. A quantidade da perda mineral e a profundidade em que esta ocorreu foram analisadas em transversais traçadas em pontos eqüidistantes do limite esmalte normal-microabrasionado. Os dados obtidos foram analisados com o teste ANOVA (p < 0,05). RESULTADOS: A Técnica de Perfilometria obteve uma boa reprodutibilidade (coeficiente de correlação intraclasse de 0,9998) e foi validada internamente. O grupo AC foi o mais agressivo, apresentando a maior profundidade de desgaste (110,51 ± 41,21 &#956;m), e a maior perda mineral (13 ± 3 peso %), com diferenças significantes em relação aos grupos WRM (p < 0,05; 9,41± 4,4 peso %) e OP (p < 0,05; 9,0 ± 3,8 peso %). O grupo OP, por outro lado, foi o menos agressivo com os menores valores para todos os parâmetros analisados, apresentando uma profundidade de desgaste menor em relação aos grupos AC (p < 0,0001), WRM (p < 0,001; 86,24 ± 27,99 &#956;m) e AF (p < 0,05; 74,46 ± 42,06 &#956;m). Os outros dois grupos apresentaram resultados intermediários para profundidade de desgaste e quantidade de perda mineral. Não houve diferença quanto à profundidade de perda mineral CONCLUSÃO: Com base em uma terminologia própria para a interface esmalte normal-microabrasionado e na aplicação de uma nova Técnica de Perfilometria, os agentes testados mostraram uma significativa diferença quanto à profundidade de desgaste, que foi condizente com a perda mineral. A nova Técnica de Perfilometria propõe o preenchimento de uma lacuna na literatura, permitindo a determinação física de profundidade de desgaste em superfícies naturalmente curvas de tecidos biológicos duros.

High-resolution three-dimensional (3D) shape reconstruction of objects has huge potential for applications in the field of design, security, entertainment, biomedicine, industrial quality control etc. Of the available techniques, optical methods have the distinctive advantage of facilitating non-contact and non-intrusive measurements. Of late, integration of optical measurement system with the computer based data processing has improved the quality of the results. Of the available techniques, structured-light illumination (Fringe Projection) is the most effective, owing its simplistic experimental architecture and analysis. Traditional Fringe Projection techniques function with the use of fringes generated using interferometric methods. With the advent of digital light projectors, digitally generated fringes have taken the place of interferometry based fringes. Despite the technological advances that this field has witnessed over last couple of decades, digital fringe projection technique still suffers from various shortcomings. This thesis presents a strategic solution to the challenges faced by the technique in its application to out-of-plane deformation measurement of objects under impact loading. First part of the thesis reports the developmental work on building an LED-Grating based optical projection system for implementation of linear-fringe projection profilometry. Successful use of the developed system in measuring out-of-plane deformation experienced by multiple targets under impact loading with a time sapling of 20,000 frames per second is re-ported. However, for performing ballistic impact measurements using the liner-fringe projection method, an order of magnitude higher time-sampling is needed. This is due to the disadvantages associated with linear fringe projection technique: (1) results in wrapped phase map (2p ambiguity) estimation, and (2) the deformation/shift of the recorded fringe pattern in the modulation direction sets a limit on unambiguously measurable whole-plane displacement. Typically, fringe pitch dictates the limit of maximum detectable displacement, and thus to be able to capture larger deformation from the earlier state, coarser fringe pitch is required to be projected; while this adversely affects the resolution of measurement system. Hence, there is a need to develop a fringe projection system which has capability for whole-plane displacement without affecting the resolution and/or necessitating higher temporal-sampling. Circular Fringe Projection (CFP) technique is proposed in the second part of the thesis as a novel solution to address the above issues. CFP technique offers additional advantage of relaxing the temporal resolution requirements of the imaging system by decoupling the maximum measurable deformation rate and the frame rate of camera. A new image analysis method is also developed to extract the underlying phase distribution of the recorded circular-fringe patterns, as the conventionally used single-frame linear-fringe analysis methods are incompetent at demodulating the circular fringes. Experimental results obtained in 3D shape measurement and whole-field out-of-plane displacement measurements of a deforming object reported in this thesis, not only confirms the ability of the proposed CFP technique in overcoming the shortcomings of the widely used linear-fringe projection technique, but also its suitability for deployment in ballistic-impact measurements.

Made available in DSpace on 2014-12-17T14:58:20Z (GMT). No. of bitstreams: 1 ChristianoJMC_DISSERT.pdf: 5726380 bytes, checksum: 57b5c167cfa539dfe52a09cb70e8a00e (MD5) Previous issue date: 2013-01-14 / Universidade Federal do Rio Grande do Norte / To enhance the maintenance practices, Oil and Gas Pipelines are inspected from the inside by automated systems called PIG (Pipeline Inspection Gauge). The inspection and mapping of defects, as dents and holes, in the internal wall of these pipelines are increasingly put into service toward an overall Structural Integrity Policy. The residual life of these structures must be determined such that minimize its probability of failure. For this reason, the investigation on the detection limits of some basic topological features constituted by peaks or valleys disposed along a smooth surface is of great value for determining the sensitivity of the measurements of defects from some combinations of circumferential, axial and radial extent. In this investigation, it was analyzed an inductive profilometric sensor to scan three races, radius r1, r2, r3, in a circular surface of low carbon steel, equipped with eight consecutive defects simulated by bulges and holes by orbit, equally spaced at p/4 rad. A test rig and a methodology for testing in laboratory were developed to evaluate the sensor response and identify their dead zones and jumps due to fluctuations as a function of topological features and scanning velocity, four speeds different. The results are presented, analyzed and suggestions are made toward a new conception of sensor topologies, more sensible to detect these type of damage morphologies / Para melhorar as pr?ticas de manuten??o, oleodutos e gasodutos s?o inspecionados internamente por sistemas automatizados denominados PIG (Pipeline Inspection Gauge). Uma inspe??o e mapeamento de danos, como ressaltos e rebaixos, na parede interna desses dutos s?o cada vez mais inseridos em pr?tica para uma pol?tica de Integridade Estrutural. A vida residual dessas estruturas deve ser determinada a fim de minimizar as probabilidades de falha. Por esta raz?o, a investiga??o no limite de detec??o de algumas caracter?sticas topol?gicas b?sicas constitu?das por picos e vales dispostas ao longo de uma superf?cie lisa ? de grande valia para a determina??o da sensibilidade nas medi??es de defeitos de alguns n?veis de combina??es circunferencial, axial e radial. Nesta pesquisa, foi analisado um sensor perfilom?trico indutivo para inspecionar tr?s ?rbitas, de raios r1, r2 e r3 numa superf?cie circular de a?o baixo carbono, equipado com oito danos consecutivos simulados por rebaixos e ressaltos, por ?rbita, uniformemente espa?adas de p/4 rad. Uma bancada de ensaio e uma metodologia para teste em laborat?rio foram desenvolvidos para avaliar a resposta do sensor e identificar suas zonas cegas devido ? flutua??o dos saltos como uma fun??o das caracter?sticas topol?gicas e inspe??o de velocidades quatro velocidades distintas. Os resultados s?o apresentados, analisados e sugest?es s?o feitas na dire??o de uma nova concep??o de topologias de sensores, mais sens?veis para detectar esses tipos de morfologias de danos

The diploma thesis deals with the use of Laser-Induced Breakdown Spectroscopy (LIBS) for depth profiling and 3D mapping of the zinc-coated steel used in the automotive industry. Before creating depth maps and depth profiles, optimization of the experiment was performed. It was shown that the LIBS technique is suited for making depth profiles and depth maps. The theoretical part deals with the description of the LIBS instrumentation, characteristics of plasma, and assembling of scientific papers which reflect the up to date knowledge about depth profiling and mapping with the use of the LIBS technique. The experimental part describes the optimization of the experiment. Gate delay, the depth and the diameter of craters using the profilometer, the position of the focal plane relative to the sample surface, and selection of spectral lines with the smallest residual signal and small scattering of data were optimized. Depth profiles of zinc, iron, chromium and manganese with the depth map of zinc and iron were made, and also the depth resolution for both elements was calculated.

Les matrices en carbure de Tungstène et Cobalt (WC‐Co) sont utilisées dans les procédés de frappe à froid de l’acier pour leur exceptionnelle capacité à résister aux phénomènes d’usure. Ces travaux ont pour objectif de mieux comprendre les mécanismes complexes qui entrainent finalement la dérive des matrices vers l’état usé. Cette complexité vient des liens étroits entre la microstructure et les propriétés mécaniques macroscopiques de ces matériaux. Pour la compréhension des mécanismes de dérive vers l’usure, une stratégie de travail en quatre étapes est établie. La première étape est le prélèvement de matrices de frappe, avec différentes durées de vie, directement sur la chaîne de production. La deuxième étape est l’identification de la rhéologie. Elle s’accompagne de la modélisation numérique du procédé de frappe pour calculer le champ des contraintes et des déformations plastiques. La troisième étape est la caractérisation localisée de l’évolution de la surface selon trois axes : les propriétés tribologiques, morphologiques, et mécaniques. On quantifie ainsi la dégradation progressive des conditions de contact corrélée avec une fragilisation des surfaces et la décohésion de grains de carbures WC. Pour comprendre les mécanismes qui conduisent à la décohésion de grains, une stratégie de modélisation numérique à l'échelle mésomécaniques 2D est mise en place. L’énergie de rupture entre un grain et le reste du matériau est modélisée par des éléments cohésifs. Ces modèles montrent que la sensibilité de chaque grain à l’arrachement dépend non seulement des conditions de contact et de la ténacité du matériau, mais également de la taille et de la configuration du grain au voisinage de la surface. / Tungsten carbide and Cobalt (WC‐Co) dies are used for cold forming processes of steel because of their exceptional performances in resisting wear phenomena. This work aims to a better understanding of the complex damage mechanisms that eventually cause wear. This complexity comes from the existing relationships between their microstructure and their macroscopic mechanical properties. For a better understanding of the damage mechanisms leading towards wear, a four‐step strategy is presented. The first step is the cold heading dies sampling directly on the production line. They are collected at different lifetimes. The second step is the identification of the die rheology. It is followed by numerical modeling of the forging process to calculate the stress field and plastic strain magnitude. The third step is to characterize the local evolution of the surface properties along three axes: the tribological, the morphological and mechanical aspects. These analyses quantify the progressive decrease of contact conditions correlated with surface embrittlement and WC carbide grains debonding. To understand the mechanisms that lead to the grains debonding, a set of 2D mesoscale contact models are performed. The fracture energy between a WC grain and the rest of the material is computed using cohesive elements. These models show that the sensitivity to debonding depends not only on the contact conditions and the material fracture toughness, but also on the grain size and grain configuration in the vicinity of the surface.

No description available.

The effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined cast iron, lined cast iron, and polyvinyl chloride was measured using pipe coupons exposed for three months. Roughness of each pipe coupon was measured with an optical surface profiler before and after exposure to inhibitors. For most materials, inhibitor did not have a significant effect on surface roughness; instead, the most significant factor determining the final surface roughness was the initial surface roughness. Coupons with low initial surface roughness tended to have an increase in surface roughness during exposure, and vice versa, implying that surface roughness tended to regress towards an average or equilibrium value. For unlined cast iron, increased alkalinity and increased temperature tended to correspond with increases in surface roughness. Unlined cast iron coupons receiving phosphate inhibitors were more likely to have a significant change in surface roughness, suggesting that phosphate inhibitors affect stability of iron pipe scales. Similar roughness data collected with new copper coupons showed that elevated orthophosphate, alkalinity, and temperature were all factors associated with increased copper surface roughness. The greatest increases in surface roughness were observed with copper coupons receiving phosphate inhibitors. Smaller increases were observed with copper coupons receiving silicate inhibitor or no inhibitor. With phosphate inhibitors, elevated temperature and alkalinity were associated with larger increases in surface roughness and blue-green copper (II) scales.. Otherwise a compact, dull red copper (I) scale was observed. These data suggest that phosphate inhibitor addition corresponds with changes in surface morphology, and surface composition, including the oxidation state of copper solids. The effects of corrosion inhibitors on copper surface chemistry and cuprosolvency were investigated. Most copper scales had X-ray photoelectron spectroscopy binding energies consistent with a mixture of Cu2O, CuO, Cu(OH)2, and other copper (II) salts. Orthophosphate and silica were detected on copper surfaces exposed to each inhibitor. All phosphate and silicate inhibitors reduced copper release relative to the no inhibitor treatments, keeping total copper below the 1.3 mg/L MCLG for all water quality blends. All three kinds of phosphate inhibitors, when added at 1 mg/L as P, corresponded with a 60% reduction in copper release relative to the no inhibitor control. On average, this percent reduction was consistent across varying water quality conditions in all four phases. Similarly when silicate inhibitor was added at 6 mg/L as SiO2, this corresponded with a 25-40% reduction in copper release relative to the no inhibitor control. Hence, on average, for the given inhibitors and doses, phosphate inhibitors provided more predictable control of copper release across changing water quality conditions. A plot of cupric ion concentration versus orthophosphate concentration showed a decrease in copper release consistent with mechanistic control by either cupric phosphate solubility or a diffusion limiting phosphate film. Thermodynamic models were developed to identify feasible controlling solids. For the no inhibitor treatment, Cu(OH)2 provided the closest prediction of copper release. With phosphate inhibitors both Cu(OH)2 and Cu(PO4)·2H2O models provided plausible predictions. Similarly, with silicate inhibitor, the Cu(OH)2 and CuSiO3·H2O models provided plausible predictions.