Cette thèse traite dela mise en correspondance de séquences appliquée au word spotting (localisation de motsclés dans des images de documents sans en interpréter le contenu). De nombreux algorithmes existent mais très peu d’entre eux ont été évalués dans ce contexte. Nous commençons donc par une étude comparative de ces méthodes sur plusieurs bases d’images de documents historiques. Nous proposons ensuite un nouvel algorithme réunissant la plupart des possibilités offertes séparément dans les autres algorithmes. Ainsi, le FSM (Flexible Sequence Matching) permet de réaliser des correspondances multiples sans considérer des éléments bruités dans la séquence cible, qu’ils se situent au début, à la fin ou bien au coeur de la correspondance. Nous étendons ensuite ces possibilités à la séquence requête en définissant un nouvel algorithme (ESC : Examplary Sequence Cardinality). Finalement, nous proposons une méthode d’appariement alternative utilisant une mise en correspondance inexacte de chaines de codes (shape code) décrivant les mots. / This thesis deals with sequence matching techniques, applied to word spotting (locating keywords in document images without interpreting the content). Several sequence matching techniques exist in the literature but very few of them have been evaluated in the context of word spotting. This thesis begins by a comparative study of these methods for word spotting on several datasets of historical images. After analyzing these approaches, we then propose a new algorithm, called as Flexible Sequence Matching (FSM) which combines most of the advantages offered separately by several other previously explored sequence matching algorithms. Thus, FSM is able to skip outliers from target sequence, which can be present at the beginning, at the end or in the middle of the target sequence. Moreover it can perform one-to-one, one-to-many and many-to-one correspondences between query and target sequence without considering noisy elements in the target sequence. We then also extend these characteristics to the query sequence by defining a new algorithm (ESC : Examplary Sequence Cardinality). Finally, we propose an alternative word matching technique by using an inexact chain codes (shape code), describing the words.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011 / Smart (SMA-Shape Memory Alloy) Technology continues to advance rapidly as engineers move closer to and understand better the industrial and commercial needs for SMA. As a matter of fact, all types of products, which exercise some type of control over their function, are rapidly making their way into the marketplace [36] Nonetheless, nowhere has been evidence in the development of a SMA impeller. Unlike traditional impellers with no control over their function and sometimes fixed angle of attack, this paper demonstrates numerical investigations using analytical algorithms (Matrix laboratory programming and excel spread sheet) and advanced computer simulation package, Engineering Fluid dynamics (EFD) into the feasibility of using a smart impeller to study the performance of a pumping system and the best angle of attack for a Shape Memory Impeller. Primarily, Bench mark data and dimensions are obtained from a standard centrifugal pump run on a FM21 demonstration unit. Using the same standard centrifugal pump, and keeping all other dimensions the same but altering the angle of attack, EFD simulations where made. From analytical algorithm and EFD comparison, it was evident that the best angle of attack is 12 degree at the outlet angle with respect to the inlet angle. From EFD results, it is palpable that, by increasing the angle of attack from 35 degree to 45 degree at the outlet there will be huge increase in flow rate by 63.47% There is also a slight decrease in the impeller Torque from 35 degrees to 42 degrees by 0.72%. It is economically feasible to work at an outlet angle of 42 degrees due to increase in efficiency of 62.1% and a drop in torque of 0.72% by varying the outlet angle from 35 degrees to 42 degree. Understanding how critical actuator design is, it should be suggested that any shape memory impeller should never be used in critical components without a prior history of thermal and mechanical loading. Therefore, a NiTi impeller constitutive model can be designed, with impeller blades made from NiTi plates, trained to remember its best angle of attack (Martensitic phase). NiTi shape memory metal alloy (plates-blades) can exist in a two different temperature-dependent crystal structures (phases) called martensite [9](lower temperature-normal pumping condition) and austenite [9] (higher temperature or parent phase-trained best angle of attack.)

The entrainment rate of Ferrosilicone (FeSi) particles was measured in a 140 mm perspex column with air as the fluidising medium. Two different types of FeSi were used, namely atomised FeSi, which is mostly spherical in shape with smooth surfaces, and milled FeSi, which is irregular with rough surfaces. Both the FeSi mixtures had the same solid density and the similar average particle diameters ranging from 38 µm to 50 µm. The size and density of these particles put them on the border between Geldart A and Geldart B powders, similar to the high temperature Fischer-Tropsch catalyst. The atomised FeSi had a slightly higher concentration in fines (8.6% vs 1.8%), but except for the difference in particle shape, the two mixtures had otherwise very similar physical properties. A substantial difference in entrainment rate was measured between the atomised and milled FeSi, where the atomised had an entrainment rate of about six times higher than the milled FeSi throughout the range of superficial velocities tested. It was shown that the higher entrainment rate cannot be attributed only to the higher fines concentration, but that the difference in particle shape had a significant effect on the entrainment rate. Several two dimensional shape characterisation techniques were used in attempt to quantify the difference between the atomised and the milled FeSi. Of these the particle circularity managed to differentiate the best between the two particle mixtures. The circularities of the atomised and the milled FeSi were found to be 0.782 and 0.711 respectively. The measured circularity was used instead of a sphericity to adjust for the effect of particle shape on the terminal velocity of the particles. The adjusted terminal velocity was then used in the elutriation rate constant correlations to see which of the popular correlations in literature predicts the entrainment rate of the FeSi the best. All of the correlations gave a poor performance in predicting the measured entrainment rates. The two correlations that performed the best were that of Choi et al. (1999) (AARE = 72.6%) and Geldart et al. (1979) (AARE = 79%). It was concluded that single particle drag and single particle terminal velocities are not adequate to incorporate the effect of particle shape on entrainment rate. The method i by which shape affects entrainment rate therefore deserves further investigation. Further studies should also be done to develop a three dimensional shape descriptor that predicts bulk behaviour better. / Dissertation (MEng)--University of Pretoria, 2008. / Chemical Engineering / unrestricted

A shape memory alloy (SMA) is an intermetallic compound able to recover, in a continuous and reversible way, a predetermined shape during a thermal cycle while generating mechanical work. In this thesis, its use in developing an actuator for a machining process is investigated. The actuator is to drive the tool cross feed into an aluminium workpiece in a finishing lathe operation. The actuator structure was designed with an output shaft to transfer the movement and force of the SMA wire outside the device. The actuator was fabricated and the experimental setup was assembled which also included a power supply control circuit, displacement sensor, temperature sensor and current sensor for feedback, and data collection and monitoring within software. PID control was implemented within the software that regulated the power supplied to the SMA, thereby providing the position control. This study covers the mechatronics system design and development of the actuator, the experiments carried out to determine performance and the results. Open loop tests were conducted to determine the maximum stroke, the effect of cooling and response to radial forces. These tests revealed the expected non-linearity of the SMA. The actuator achieved the rated maximum stroke of 3-4 percent. The forced cooling test showed a general improvement of approximately 65 percent with fans. The radial force tests showed the value of the maximum stroke remained unaffected by force. The results from the closed loop tests responses with a tuned PID controller produced a stable system for various displacement setpoints. The actuator had a feed rate of 0.25 mm/s and an accuracy of 0.0153mm, which was within the acceptable accuracy for turning operations. The system was deemed accurate for a conventional lathe machine cross feed.

A multi-functional (sensing -actuating) greenhouse ventilation window heated/cooled naturally by convection was designed to overcome different industry challenges in terms of designing smart applications. This ventilation window design includes a three-pulley system to reduce the load on the NiTi actuator and enhance its long-life time. In addition, using the NiTi actuator allows energy saving due to natural phase transformation induction (i.e. convection) and high force generation compared to the small NiTi wire mass. Structural analysis was used to determine the force generated in the “C-shaped” NiTi wire after loading. Transient thermal and structural analysis also was used to investigate the strain rate effects on the shape memory response of “C shaped” NiTi alloy element under different thermomechanical loadings and boundary conditions. Two types of loading have been applied isothermally or at adiabatic conditions. The results showed a significant effect of the high loading rates on increasing the stress plateau which is caused by the corresponding shift in the transformation temperatures. As a result, it could be expected that the actuator life time could be reduced when a rapid, as opposed to a slow loading rate, is adopted. In addition, the dynamic loading of the NiTi leads to a decrease of the recoverable strain. Experimental work was done to validate the simulation model by testing a commercial NiTi sample dynamically and compare the macroscopic displacement during mechanical loading and the strain recovery process.

Les implants cochléaires (IC) sont utilisés pour traiter la surdité profonde en insérant chirurgicalement un réseau d'électrodes dans l'organe de l'audition, la cochlée. Les images tomodensitométriques (TDM) pré et post-opératoires sont utilisées couramment pour la planification chirurgicale et l'évaluation de l'implantation cochléaire. Cependant, en raison de la petite taille et de la topologie complexe de la cochlée, l'information anatomique qui peut être extraite des images est limitée. Le premier axe de ce travail vise à définir des méthodes automatiques de traitement d'images adaptées à la forme en spirale de la cochlée pour étudier en étudier la variabilité à partir d'images de micro-TDM (μTDM) haute résolution. Le deuxième axe vise à développer et à évaluer un nouveau modèle paramétrique de forme cochléaire. Le modèle est appliqué pour extraire des paramètres cliniquement pertinents spécifiques au patient, tels que la profondeur d'insertion maximale des portes électrode. Grâce à la quantification de l'incertitude, fournie par le modèle, la fiabilité des segmentations issues de TDM a pu être évaluée par rapport à la vérité terrain fournie par μTDM. Enfin, le dernier axe concerne un modèle de forme cochléaire (et de ses sous-structures) et d'apparence combiné dans un cadre bayésien probabiliste génératif. La méthode de segmentation proposée a été appliquée à une grande base de données de 987 images de TDM et a permis la caractérisation statistique de la variabilité anatomique cochléaire ainsi que la quantification de la symétrie bilatérale. Ce travail ouvre la voie à de nouvelles applications cliniques telles que l'amélioration du diagnostic en identifiant les formes cochléaires pathologiques ; la planification préopératoire du choix de l'électrode et de l'axe d'insertion ; l'estimation postopératoire de la position de l'électrode et évaluation de l'implantation ; et la simulation d'implantation cochléaire. / Cochlear implants (CI) are used to treat hearing loss by surgically inserting an electrode array into the organ of hearing, the cochlea. Pre- and post-operative CT images are used routinely for surgery planning and evaluation of cochlear implantation. However, due to the small size and the complex topology of the cochlea, the anatomical information that can be extracted from the images is limited. The first focus of this work aims at defining automatic image processing methods adapted to the spiral shape of the cochlea to study the cochlear shape variability from high-resolution μCT images. The second focus aims at developing and evaluating a new parametric cochlear shape model. The model is applied to extract patient-specific clinically relevant metrics such as the maximal insertion depth of CI electrode arrays. Thanks to the uncertainty quantification, provided by the model, we can assess the reliability of CT-based segmentation as compared to the ground truth segmentation provided by μCT scans. Finally, the last focus concerns a joint model of the cochlear shape (and its substructures) model and its appearance within a generative probabilistic Bayesian framework. The proposed segmentation method was applied to a large database of 987 CT images and allowed the statistical characterization of the cochlear anatomical variability along with the quantification of the bilateral symmetry. This work paves the way to novel clinical applications such as improved diagnosis by identifying pathological cochlear shapes; preoperative optimal electrode design and insertion axis planning; postoperative electrode position estimation and implantation evaluation; and cochlear implantation simulation.

In part one we show that for a compact, metric, locally path-connected topological space X, the shape group of X - as defined in Foundations of Shape Theory by Mardesic and Segal - is isomorphic to the inverse limit of discrete homotopy groups introduced by Conrad Plaut and Valera Berestovskii. We begin by providing the reader preliminary definitions of the fundamental group of a topological space, inverse systems and inverse limits, the Shape Category, discrete homotopy groups, and culminate by providing an isomorphism of the shape and deck groups for peano continua. In part two we develop work and provide further classification of Sharkovskii topological groups, which we call Sharkovskii Groups. We culminate in proving the fact that a locally compact Sharkovskii group must either be the real numbers if it is not compact, or a torsion-free solenoid if it is compact.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18587号 / 工博第3948号 / 新制||工||1607(附属図書館) / 31487 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 北條 正樹, 教授 北村 隆行, 教授 琵琶 志朗 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Topology Optimization has been proven to be a useful tool in discovering non-intuitive optimal designs subject to certain design constraints. The results of Topology Optimization are either represented as a tessellation object composed of thousands of triangular surfaces, or as a point cloud. In either case, the results of Topology Optimization are not suited for use in subsequent steps of the design process which require 3D parametric CAD (Computer Aided Design) models. Converting Topology Optimization results into parametric CAD geometry by hand is an extremely tedious and time consuming process which is highly subjective. This thesis presents a shape recognition algorithm that uses a feature by feature CAD-centric approach to convert Topology Optimization results into parametric CAD geometry. This is accomplished by fitting 2D cross section geometry to various parts of a given feature through the use of Shape Templates and then constructing 3D surfaces through the set of 2D cross sections. This algorithm aids in measuring the geometric approximation error of the generated geometry as compared to the optimal model, and standardizes the process through automation techniques. It also aids the designer / engineer in managing the direct tradeoff between closeness of geometric approximation (measured by volumetric comparison) and model complexity (measured by the number of parameters required to represent the geometry).

Actuator applications of shape memory alloys have typically been limited by their phase transformation temperatures to around 100 degrees C. However, recently with a focus on aerospace and turbomachinery applications there have been successful efforts to increase the phase transformation temperatures. Several of these alloy development efforts have involved ternary and quaternary elemental additions (e.g., Pt, Pd, etc.) to binary NiTi alloys. Experimentally assessing the effects of varying composition and thermo-mechanical processing parameters can be cost intensive, especially when expensive, high-purity elemental additions are involved. Thus, in order to save on development costs there is value in establishing a methodology that facilitates the fabrication, processing and testing of smaller specimens, rather than larger specimens from commercial billets. With the objective of establishing such a methodology, this work compares thermo-mechanical test results from bulk dog-bone tensile Ni29.5Ti50.5Pd20 samples (7.62 mm diameter) with that of thin wires (100 μm-150 µm diameter) extracted from comparable, untested bulk samples by wire electrical-discharge machining (EDM). The wires were subsequently electropolished to different cross-sections, characterized with Scanning Electron Microscopy, Transmission Electron Microscopy and Energy Dispersive X-Ray Spectroscopy to verify the removal of the heat affected zone following EDM and subjected to Laser Scanning Confocal Microscopy to accurately determine their cross-sections before thermo-mechanical testing. Stress-strain and load-bias experiments were then performed on these wires using a dynamic mechanical analyzer and compared with results established in iv previous studies for comparable bulk tensile specimens. On comparing the results from a bulk tensile sample with that of the micron-scale wires, the overall thermomechanical trends were accurately captured by the micron-scale wires for both the constrained recovery and monotonic tensile tests. Specifically, there was good agreement between the stress-strain response in both the martensitic and austenitic phases, the transformation strains at lower stresses in constrained recovery, and the transformation temperatures at higher stresses in constrained recovery. This work thus validated that carefully prepared micron-diameter samples can be used to obtain representative bulk thermo-mechanical properties, and is useful for fabricating and optimizing composition and thermomechanical processing parameters in prototype button melts prior to commercial production. This work additionally assesses potential applications of high temperature shape memory alloy actuator seals in turbomachinery. A concept for a shape memory alloy turbine labyrinth seal is also presented. Funding support from NASA’s Fundamental Aeronautics Program, Supersonics Project (NNX08AB51A) and Siemens Energy is acknowledged.