Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-10-09T18:35:29Z No. of bitstreams: 0 / Made available in DSpace on 2017-10-09T18:35:29Z (GMT). No. of bitstreams: 0 / Neste trabalho foram determinadas as condições para a soldagem de chapas grossas de aço carbono ASTM A36 com aço baixo-liga temperado e revenido ASTM A514 Grau Q empregando-se o processo arame tubular. Para tanto foram soldadas diversas peças de testes com o intuito de se avaliar as condições mais adequadas de preparação e soldagem de juntas dissimilares destes materiais. A preparação foi realizada por meio de corte térmico. A temperatura de preaquecimento foi determinada através de modelos matemáticos, pelas recomendações das normas AWS D1.1 e DIN EN 1011-2 sendo posteriormente avaliada por intermédio do teste de soldabilidade tipo CTS Controlled Thermal Severity. Os parâmetros de soldagem foram determinados a partir da qualificação de um procedimento de soldagem, conforme a norma AWS D1.1. Foram avaliadas as consequências do emprego do tratamento térmico de alívio de tensões após soldagem (TTAT), pelos testes de dureza Vickers e impacto Charpy. A caracterização microestrutural foi realizada por meio de microscopia óptica e microscopia eletrônica de varredura. A caracterização das superfícies oxicortadas evidenciou os efeitos da descarbonetação e também da carbonetação. A temperatura de pré-aquecimento de 160°C determinada por meio da metodologia recomendada pelas normas AWS D1.1 e DIN EN 1011-2 mostrou-se satisfatória nos testes de soldabilidade. Foi possível a qualificação do procedimento de soldagem (EPS) com requisitos de impacto na condição "como soldado", porém na condição "após TTAT", os baixos valores de tenacidade obtidos no metal de solda, inferiores a 27J, não permitiram a qualificação de uma EPS com requisitos de impacto. Foi observada a ausência de trincas intergranulares tanto na zona afetada pelo calor quanto no metal de base ASTM A514, porém foi revelada a presença de microfases frágeis no metal de solda na condição "como soldado", especificamente na região da raiz, intensificadas pelo efeito da diluição. O aumento do teor de carbono na raiz, a presença de microfases frágeis, a grande fração de grãos colunares e de ferrita proeutetóide combinados com a baixa fração de ferrita acicular no metal de solda contribuíram para os baixos valores de tenacidade encontrados na condição "como soldado". Após o TTAT observou-se uma queda acentuada da tenacidade, inferior a 27J, do metal de solda devido à fragilização provocada pela precipitação e coalescimento de carbonetos de ferro. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-17T17:51:24Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-17T17:51:24Z (GMT). No. of bitstreams: 0 / Atualmente, uns dos grandes desafios para a indústria automobilística é aumentar o desempenho do conjunto mecânico responsável por selar a câmara de combustão interna de motores automotivos e também reduzir os seus custos de obtenção. O objetivo deste trabalho foi o de tratar termicamente insertos de assentos de válvulas (do inglês valve seat insert, VSI) obtidos pela rota de metalurgia do pó. Esta técnica possibilitou a substituição do cobalto e do chumbo, devido ao seu elevado custo e efeito toxicológico, respectivamente. Ao longo do trabalho foram avaliados VSI obtidos com três misturas de pós diferentes, sendo que os elementos comuns nestas três misturas foram os pós de ferro, sulfeto de manganês, carboneto de nióbio, grafite, estearato de zinco e cobre. Em cada uma destas misturas variou-se apenas os tipos de pós de aços rápidos e aço ferramenta utilizado, sendo estes o aço rápido AISI M3:2 (Mistura 1), aço rápido AISI M2 (Mistura 2) e aço ferramenta AISI D2 (Mistura 3). Os tratamentos térmicos aplicados aos VSI consistiram em têmpera ao ar e têmpera ao óleo, ambas seguidas de duplo revenimento em sete temperaturas equidistantemente diferentes, variando de 100 °C a 700 °C. Os ciclos dos tratamentos térmicos foram determinados por meio da utilização de termopares do tipo k acoplados à um sistema de aquisição de dados. As propriedades físicas e mecânicas dos VSI foram determinadas através da dureza aparente, densidade aparente e resistência à ruptura radial. A caracterização microestrutural foi realizada utilizando-se a microscopia óptica e microscopia eletrônica de varredura. A composição química foi determinada por meio da análise elementar e por espectrometria de fluorescência de energia dispersiva de raios X. Os melhores resultados em relação às propriedades mecânicas dos VSI foram obtidas para os insertos temperados ao ar e duplamente revenido a 600 °C para a Mistura 1 e Mistura 2, e a 500 °C para Mistura 3. Já para a têmpera ao óleo, as melhores respostas foram para os VSI obtidos com a Mistura 1 duplamente revenida a 400 °C e a, 300 °C para os componentes obtidos com a Mistura 2 e Mistura 3. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Verification of users’ identities are normally carried out via PIN-codes or ID- cards. Biometric identification, identification of unique body features, offers an alternative solution to these methods. Fingerprint scanning is the most common biometric identification method used today. It uses a simple and quick method of identification and has therefore been favored instead of other biometric identification methods such as retina scan or signature verification. In this report biometric security systems have been evaluated based on fingerprint scanners. The evaluation method focuses on copies of real fingers, artificial fingers, as intrusion method but it also mentions currently used algorithms for identification and strengths and weaknesses in hardware solutions used. The artificial fingers used in the evaluation were made of gelatin, as it resembles the surface of human skin in ways of moisture, electric resistance and texture. Artificial fingers were based on ten subjects whose real fingers and artificial counterpart were tested on three different fingerprint scanners. All scanners tested accepted artificial fingers as substitutes for real fingers. Results varied between users and scanners but the artificial fingers were accepted between about one forth and half of the times. Techniques used in image enhancement, minutiae analysis and pattern matching are analyzed. Normalization, binarization, quality markup and low pass filtering are described within image enhancement. In minutiae analysis connectivity numbers, point identification and skeletonization (thinning algorithms) are analyzed. Within pattern matching, direction field analysis and principal component analysis are described. Finally combinations of both minutiae analysis and pattern matching, hybrid models, are mentioned. Based on experiments made and analysis of used techniques a recommendation for future use and development of fingerprint scanners is made.

Measuring 3D surface geometry with precision and accuracy is an important part of many engineering and scientific tasks. 3D Scanning techniques measure surface geometry by estimating the locations of sampled surface points. In recent years, Structured-Light 3D scanners have gained significant popularity owing to their ability to produce highly accurate scans in real-time at a low cost. In this thesis we describe an approach for Structured-Light 3D scanning using a digital camera and a digital projector. We utilise the projective geometric relationships between the projector and the camera to carry out both an implicit calibration of the system and to solve for 3D structure. Our approach to geometric calibration is flexible, reliable and amenable to robust estimation. In addition, we model and account for the radiometric non-linearities in the projector such as gamma distortion. Finally, we apply a post-processing step to efficiently smooth out high-frequency surface noise while retaining the structural details. Consequently, the proposed work reduces the computational load and set-up time of a Structured-Light 3D scanner; thereby speeding up the whole scanning process while retaining the ability to generate highly accurate results. We demonstrate the accuracy of our scanning results on real-world objects of varying degrees of surface complexity. Introduction The projective geometry for a pair of pin-hole viewing devices is completely defined by their intrinsic calibration and their relative motion or extrinsic calibration in the form of matrices. For a Euclidean reconstruction, the geometry elements represented by the calibration matrices must be parameterised and estimated in some form. The use of a projector as the ‘second viewing’ device has led to numerous approaches to model and estimate its intrinsic parameters and relative motion with respect to the camera's 3D co-ordinate system. Proposed thesis work assimilates the benefits of projective geometry constructs such as Homography and the invariance of the cross-ratios to simplify the system calibration and the 3D estimation processes by an implicit modeling of the projector's intrinsic parameters and its relative motion. Though linear modeling of the projective geometry between a camera-projector view-pair captures the most essential aspects of the underlying geometry, it does not accommodate system non-linearities due to radiometric distortions of a projector device. We propose an approach that uses parametric splines to model the systematic errors introduced by radiometric non-linearities and thus correct for them. For 3D surfaces reconstructed as point-clouds, noise manifests itself as some high-frequency variations for the resulting mesh. Various pre and/or post processing techniques are proposed in the literature to model and minimize the effects of noise. We use simple bilateral filtering of the depth-map for the reconstructed surface to smoothen the surface while retaining its structural details. Modeling Projective Relations In our approach for calibrating the projective-geometric structure of a projector-camera view-pair, the frame of reference for measurements is attached to the camera. The camera is calibrated using a commonly used method. To calibrate the scanner system, one common approach is to project sinusoidal patterns onto the reference planes to generate reference phase maps. By relating the phase-information between the projector and image pixels, a dense mapping is obtained. However, this is an over-parameterisation of the calibration information. Since the reference object is a plane, we can use the projective relationships induced by a plane to implicitly calibrate the projector geometry. For the estimation of the three-dimensional structure of the imaged object, we utilise the invariance of cross-ratios along with the calibration information of two reference planes. Our formulation is also extensible to utilise more than two reference plane to compute more than one estimate of the location of an unknown surface point. Such estimates are amenable to statistical analysis which allows us to derive both the shape of an object and associate reliability scores to each estimated point location. Radiometric Correction Structured-light based 3D scanners commonly employ phase-shifted sinusoidal patterns to solve for the correspondence problem. For scanners using projective geometry between a camera and a projector, the projector's radiometric non-linearities introduce systematic errors in establishing correspondences. Such errors manifest as visual artifacts which become pronounced when fewer phase-shifted sinusoidal patterns are used. While these artifacts can be avoided by using a large number of phase-shifts, doing so also increases the acquisition time. We propose to model and rectify such systematic errors using parametric representations. Consequently, while some existing methods retain the complete reference phase maps to account for such distortions, our approach describes the deviations using a few model parameters. The proposed approach can be used to reduce the number of phase-shifted sinusoidal patterns required for codification while suppressing systematic artifacts. Additionally, our method avoids the 1D search steps that are needed when a complete reference phase map is used, thus reducing the computational load for 3D estimation. The effectiveness of our method is demonstrated with reconstruction of some geometric surfaces and a cultural figurine. Filtering Noise For a structured-light 3D scanner, various sources of noise in the environment and the devices lead to inaccuracies in estimating the codewords (phase map) for an unknown surface, during reconstruction. We examine the effects of such noise factors on our proposed methods for geometric and radiometric estimation. We present a quantitative evaluation for our proposed method by scanning the objects of known geometric properties or measures and then computing the deviations from the expected results. In addition, we evaluate the errors introduced due to inaccuracies in system calibration by computing the variance statistics from multiple estimates for the reconstructed 3D points, where each estimate is computed using a different pair of reference planes. Finally, we discuss the efficacy of certain filtering techniques in reducing the high-frequency surface noise when applied to: (a) the images of the unknown surface at a pre-processing stage, or (b) the respective phase (or depth) map at a post-processing stage. Conclusion In this thesis, we motivate the need for a procedurally simple and computationally less demanding approach for projector calibration. We present a method that uses homographies induced by a pair of reference planes to calibrate a structured-light scanner. By using the projective invariance of the cross-ratio, we solved for the 3D geometry of a scanned surface. We demonstrate the fact that 3D geometric information can be derived using our approach with accuracy on the order of 0.1 mm. Proposed method reduces the image acquisition time for calibration and the computational needs for 3D estimation. We demonstrate an approach to effectively model radiometric distortions for the projector using cubic splines. Our approach is shown to give significant improvement over the use of complete reference phase maps and its performance is comparable to that of a sate-of-the-art method, both quantitatively as well as qualitatively. In contrast with that method, proposed method is computationally less expensive, procedurally simpler and exhibits consistent performance even at relatively higher levels of noise in phase estimation. Finally, we use a simple bilateral filtering on the depth-map for the region-of-interest. Bilateral filtering provides the best trade-off between surface smoothing and the preservation of its structural details. Our filtering approach avoids computationally expensive surface normal estimation algorithms completely while improving surface fidelity.

The world has recently witnessed the widespread of 3D printing technology. In the shadow of this development a new means of freezing time was born: 3D figurines. A 3D figurine is a mini version of oneself; a little sculpture manufactured by 3D Printers. These 3D figurines are sold for a profit by so called 3D Print Stores to consumers. For the production of such a 3D figurine one needs 3D Body Scanners. It is from the perspective of a producer of 3D Body Scanners that this master thesis was written. The objective was to establish whether or not the company should tap into that new market segment of 3D Print Stores. Furthermore a market entry strategy was to be developed. Thus a marketing research study was performed. For the analysis of the market segment primary and secondary data was scrutinized, which was gathered through expert interviews and desktop research. The primary scope of the study was limited to Germany. Overall the market segment proved to be promising, as consumers regard 3D figurines as a more sophisticated alternative to a digital photo. Competition is currently low, but the threat of new players entering the segment is high. Thus a market entry strategy was elaborated that suggests tapping into the market as fast as possible; thereby obtaining a first mover advantage and pre-empting market space. Furthermore a differentiation strategy was proposed to shield against growing competition.

The objective of Master’s Thesis is to research the utilization of line optical sensors for object location´s and speed measurement in cooperation with PROTOTYPA company. At the beginning of the Thesis there is an explanation of CCD sensor components and photodiods working principals. Further are discussed particular methods of object sensing. There are schematics of different sensor locations and flying object. The other step deals with introduction to the question of ray impact on sensor in the way of using different light sources and optical systems. In the other part of the Thesis are presented two sensors, which have been chosen by PROTOTYPA company workers. Final part of the Thesis deals with description of executed experimental measurement with LCCD 2048S-14 type of sensor. Experiments are aimed for statical and dynamical processes. In statical part was checked displaying of fixed objects on CCD sensor in internal spaces on the assumption that changing of object-lens focalization, object´s high and shape. For the evaluation was used of MATLAB program. Dynamical part of measurement is aimed for moving objects.

The diploma thesis is focused to possibility utilizing of optical scanners TRITOP and ATOS for set up geometry of wheels. In background research are described the most important parameters of wheel suspension and devices for measuring these parameters. Practical part is concerned with progression of measurement, results and with determination coordinates of kinematic points. These points are made 3D model of forward and backward suspension wheels. This model helps to make kinematic characteristics and its progression due to attitude of wheel. In last part is described possibility to utilizing of optical scanner ATOS to common measurement of geometry wheels.

<p>Static terrestrial laser scanners have been increasingly used in three-dimensional data acquisition since it can rapidly provide accurate measurements with high resolution. Several scans from multiple viewpoints are necessary to achieve complete coverage of the surveyed objects due to occlusion and large object size. Therefore, in order to reconstruct three-dimensional models of the objects, the task of registration is required to transform several individual scans into a common reference frame. This thesis introduces three alternative approaches for the coarse registration of two adjacent scans, namely, feature-based approach, pseudo-conjugate point-based method, and closed-form solution. In the feature-based approach, linear and planar features in the overlapping area of adjacent scans are selected as registration primitives. The pseudo-conjugate point-based method utilizes non-corresponding points along common linear and planar features to estimate transformation parameters. The pseudo-conjugate point-based method is simpler than the feature-based approach since the partial derivatives are easier to compute. In the closed-form solution, a rotation matrix is first estimated by using a unit quaternion, which is a concise description of the rotation. Afterward, the translation parameters are estimated with non-corresponding points along the linear or planar features by using the pseudo-conjugate point-based method. Alternative approaches for fitting a line or plane to data with errors in three-dimensional space are investigated.</p><p><br></p><p>Experiments are conducted using simulated and real datasets to verify the effectiveness of the introduced registration procedures and feature fitting approaches. The proposed two approaches of line fitting are tested with simulated datasets. The results suggest that these two approaches can produce identical line parameters and variance-covariance matrix. The three registration approaches are tested with both simulated and real datasets. In the simulated datasets, all three registration approaches produced equivalent transformation parameters using linear or planar features. The comparison between the simulated linear and planar features shows that both features can produce equivalent registration results. In the real datasets, the three registration approaches using the linear or planar features also produced equivalent results. In addition, the results using real data indicates that the registration approaches using planar features produced better results than the approaches using linear features. The experiments show that the pseudo-conjugate point-based approach is easier to implement than the feature-based approach. The pseudo-conjugate point-based method and feature-based approach are nonlinear, so an initial guess of transformation parameters is required in these two approaches. Compared to the nonlinear approaches, the closed-form solution is linear and hence it can achieve the registration of two adjacent scans without the requirement of any initial guess for transformation parameters. Therefore, the pseudo-conjugate point-based method and closed-form solution are the preferred approaches for coarse registration using linear or planar features. In real practice, the planar features would have a better preference when compared to linear features since the linear features are derived indirectly by the intersection of neighboring planar features. To get enough lines with different orientations, planes that are far apart from each other have to be extrapolated to derive lines.</p><div><br></div>

The design and implementation of a handheld scanner that can help sight-impaired or even blind users to manually scan and read text is discussed in this dissertation. A thorough investigation of all the elements involved in such a system is presented and optimal solutions are proposed. A unique velocity compensation technique based solely on optical information obtained by the scanning device is discussed and a real time segmentation technique based on topological properties (Quasi-Topological Codes) of connected segments is presented. A skew detection algorithm is discussed that can trace typed and printed text manual1y scanned with skew up to 15 degrees and can guide blind users to properly scan a document. Real time extraction of quasitopological codes for automatic text recognition and the hardware implementation is also discussed in this work. A hierarchical optical character recognition method is proposed which is based on syntactic and metric analysis of the Quasi-Topological Codes and their position in the scanned image. The proposed method can recognize characters stretched to approximately two times their original width or rotated by a few degrees. Finally, an automated iterative learning process is discussed which includes generalization of the recognition logic and dynamic adaptation of the syntactic and metric recognition rules. / Ph. D.

Purpose – The purpose of this study is to analyze a supply chain, where manufacturing is outsourced, to identify risk zones where any quantity difference could occur, the cause of quantity difference and the measures that could be taken to reduce the quantity difference.   Method – In order to achieve the purpose a literature study and a case study has been carried out. The case study consisted of interviews, observations and document studies and have generated empirical data. In the analysis of the collected data a fishbone diagram has been established and pattern matching has been applied. Findings – The case company's supply chain was mapped to identify risk zones, risk factors, and measures for the risk factors. The biggest risk zones identified in the cas company was picking and the store's inventory. The risk factors that were considered to be contributing most to the quantity difference was the lack of communication, mistakes, lack of standards, lack of security and barcode scanners. The measures that have been presented are improving communication, introduction of new standards, upgrading of bar code readers, enhancing safety and eliminating the possibility of making mistakes. Implications – With the help of the proposals that the authors have developed, the identified risk factors could be counteracted. Before proposed measures are implemented, all personnel should first and foremost take part of the mapping of the supply chain to understand how things work together. Method discussion – To achieve reliable results triangulation has been used when interviews, observation and document studies have been conducted. The internal validity is considered to have been strengthened by pattern matching when empirical data has been compared with theory. Since the respondents' answers have been similar the internal validity has been further strengthened and therefore credible. / Syfte – Studiens syfte är att analysera en försörjningskedja, där tillverkningen är outsourcad, för att upptäcka riskzoner där en eventuell kvantitetsdifferens skulle kunna uppstå, orsak till kvantitetsdifferens samt vilka åtgärder som skulle kunna vidtas för att minska kvantitetsdifferens. Metod – För att uppnå syftet har litteraturstudier samt en fallstudie genomförts. Fallstudien har bestått av intervjuer, observationer samt dokumentstudier och har genererat empirisk data. Vid analys av insamlad data har ett fiskbensdiagram upprättats samt mönsterpassning tillämpats. Resultat – Fallföretagets försörjningskedja kartlades för att identifiera riskzoner, riskfaktorer samt åtgärder till riskfaktorerna. De största riskzonerna som identifierades på fallföretaget var plockning samt butikslager. De riskfaktorer som ansågs vara mest bidragande till kvantitetsdifferens var kommunikationsbrist, misstag, bristfälliga standarder, brist på bevakning samt streckkodsläsare. Åtgärderna som har presenterats är förbättring av kommunikation, införande av nya standarder, uppgradering av streckkodsläsare, förhöjning av säkerhet samt eliminering av möjlighet att begå misstag. Implikationer – Med hjälp av de åtgärdsförslag som författarna har tagit fram kan de identifierade riskfaktorerna motverkas. Innan studiens åtgärdsförslag implementeras bör all personal först och främst ta del av kartläggningen av försörjningskedjan för att förstå hur aktiviteterna samverkar. Metoddiskussion – För att uppnå ett tillförlitligt resultat har triangulering använts då intervjuer, observationer och dokumentstudier har genomförts. Den interna validiteten anses ha stärkts genom mönsterpassning då empiri har jämförts med teori. Eftersom att respondenternas svar har varit likartade anses den interna validiteten stärkts ytterligare och är därmed trovärdig.