Image understanding and feature extraction for applications in industry and mapping

Bibliography: p. 212-220.The aim of digital photogrammetry is the automated extraction and classification of the three dimensional information of a scene from a number of images. Existing photogrammetric systems are semi-automatic requiring manual editing and control, and have very limited domains of application so that image understanding capabilities are left to the user. Among the most important steps in a fully integrated system are the extraction of features suitable for matching, the establishment of the correspondence between matching points and object classification. The following study attempts to explore the applicability of pattern recognition concepts in conjunction with existing area-based methods, feature-based techniques and other approaches used in computer vision in order to increase the level of automation and as a general alternative and addition to existing methods. As an illustration of the pattern recognition approach examples of industrial applications are given. The underlying method is then extended to the identification of objects in aerial images of urban scenes and to the location of targets in close-range photogrammetric applications. Various moment-based techniques are considered as pattern classifiers including geometric invariant moments, Legendre moments, Zernike moments and pseudo-Zernike moments. Two-dimensional Fourier transforms are also considered as pattern classifiers. The suitability of these techniques is assessed. These are then applied as object locators and as feature extractors or interest operators. Additionally the use of fractal dimension to segment natural scenes for regional classification in order to limit the search space for particular objects is considered. The pattern recognition techniques require considerable preprocessing of images. The various image processing techniques required are explained where needed. Extracted feature points are matched using relaxation based techniques in conjunction with area-based methods to 'obtain subpixel accuracy. A subpixel pattern recognition based method is also proposed and an investigation into improved area-based subpixel matching methods is undertaken. An algorithm for determining relative orientation parameters incorporating the epipolar line constraint is investigated and compared with a standard relative orientation algorithm. In conclusion a basic system that can be automated based on some novel techniques in conjunction with existing methods is described and implemented in a mapping application. This system could be largely automated with suitably powerful computers

The design and implementation of a flexible manufacturing system for a surface mounting production line

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering.The viability of introducing a Surface Mount production line is chiefly determined by the reliability characteristics of the components being used. Surface Mount Technology (SMT) is entirely new and although related to traditional through-hole processes, requires different components, assembly techniques and design methods. The purpose of the literature survey is primarily to determine whether surface mount components meet today's industrial requirements with respect to their manufacturing reliability and availability. A brief review of the evolution of SMT is also presented. This study finds that the implementation of SMT should be given highest priority by manufacturing companies in order to maintain their share of the marketplace. Surface Mount Technology embodies a totally new automated circuit assembly process, using a new generation of electronic comporents: surface mounted devices (SMDs). Smaller than conventional components, SMDs are placed onto the surface of the substrate. From this, the fundamental difference between SMD assembly and convencional through-hole component assembly arises; SMD component positioning is relative, not absolute. When a through-hole component is inserted into a pcb, either the leads go through the hales or they don't. An SMD, however, is placed onto the substrate surface, it's position only relative to the solder lands, and placement accuracy is therefore influenced by variations in the substrate track pattern, component size, and placement machine accuracy. Other factors influence the layout of SMD substrates. For example, will the board be a mixed-print ( a combination of through-hole components and SMDs) or an all-SMD design? Will SMDs be placed on one side of the substrate or both? And there are process considerations like what type of machine will place the components and how will they be soldered? This project describes in detail the processes involved in setting up an SMT facility. A simulation program was developed to verify the viability of these processes. The simulation program was also applied to an existing SMT facility and together with developed optimization software, attempted to identify and resolve some of the major problems. All this was achieved, and the extent to which simulation could be used as an efficient production tool, was highlighted.AC201

Outlier detection approach for PCB testing based on Principal Component Analysis, An

2011 Spring.Includes bibliographical references.Capacitive Lead Frame Testing, a widely used approach for printed circuit board testing, is very effective for open solder detection. The approach, however, is affected by mechanical variations during testing and by tolerances of electrical parameters of components, making it difficult to use threshold based techniques for defect detection. A novel approach is presented in this thesis for identifying boardruns that are likely to be outliers. Based on Principal Components Analysis (PCA), this approach treats the set of capacitance measurements of individual connectors or sockets in a holistic manner to overcome the measurement and component parameter variations inherent in test data. Effectiveness of the method is evaluated using measurements on different types of boards. Based on multiple analyses of different measurement datasets, the most suitable statistics for outlier detection and relative parameter values are also identified. Enhancements to the PCA-based technique using the concept of test-pin windows are presented to increase the resolution of the analysis. When applied to one test window at a time, PCA is able to detect the physical position of potential defects. Combining the basic and enhanced techniques, the effectiveness of outlier detection is improved. The PCA based approach is extended to detect and compensate for systematic variation of measurement data caused by tilt or shift of the sense plate. This scheme promises to enhance the accuracy of outlier detection when measurements are from different fixtures. Compensation approaches are introduced to correct the 'abnormal' measurements due to sense-plate variations to a 'normal' and consistent baseline. The effectiveness of this approach in the presence of the two common forms of mechanical variations is illustrated. Potential to use PCA based analysis to estimate the relative amount of tilt and shift in sense plate is demonstrated

Development of a computational model for predicting solar wind flows past nonmagnetic terrestrial planets

A computational model for the determination of the detailed plasma and magnetic field properties of the global interaction of the solar wind with nonmagnetic terrestrial planetary obstacles is described. The theoretical method is based on an established single fluid, steady, dissipationless, magnetohydrodynamic continuum model, and is appropriate for the calculation of supersonic, super-Alfvenic solar wind flow past terrestrial ionospheres

The Chemistry of some Di- and Tri-Phenylmethane dyes

Two series of dyes have been prepared: a comprehensive series of novel, unsymmetrical Malachite Green type dyes containing different amino substituents in the 4-positions of the phenyl rings and a series of symmetrical Michier's Hydrol Blue type dyes. Both series of dyes have been synthesised from the relevant carbinols or hydrols. The amino substituents used were dimethylamino, diethylamino, pyrrolidino, piperidino, morpholino, thiomorpholino and N-methylpiperazino. The rates of ailcalirie hydrolysis of the dyes at various hydroxide ion concentrations and temperatures have been investigated with a view to elucidating the reaction mechanism and the nature of substituent effects. The rate data obtained for each dye studied have been used to obtain thermodynamic activation parameters and to test the applicability of an isokinetic relationship in the dye systems. The various methods of computation and their results have been compared and discussed in relation to literature data for similar dyes. A stopped-flow technique was used for the kinetic investigation of the fast reactions associated with the unstable dyes studied. The analysis of kinetic data using single substituent parameter regression techniques has enabled substituent constants for piperidine, thiomorpholine and N-methylpiperazine to be interpolated. The steric and electronic effects of the terminal amino substituents on the visible absorption spectra of the dyes have been examined in solvents of varying acidity. The steric and electronic symmetry of the Malachite Green type dyes has been investigated and is discussed. The results from the spectral investigation and the kinetic study indicate that diphenylmethane dyes are considerably less stable than the corresponding triphenylmethane dyes and the reasons for this behaviour are discussed. In addition, piperidino, morpholino, thiomorpholino and N-methylpiperazino are less able to stabilise a dye by electron donation than dimethylamino, diethylamino and pyrrolidino and the reasons for this behaviour are also discussed. The 'H and 13C nmr spectra of the dyes and carbinols have been recorded. Certain chemical shifts have been used to determine the relative electron donor ability of the terminal amino groups. The results from the 'H and 13C nmr spectra are discussed in relation to the steric and electronic effects of the heterocycic moieties

Low Frequency Waves Upstream and Downstream of the Terrestrial Bow Shock

The thesis makes use of the four point measurements provided by the Cluster spacecraft mission and determines not only wave vectors but also dispersion relations, propagation patterns, and wave number spectra in the upstream and the downstream regions of the terrestrial bow shock. Furthermore, those wave properties are determined in a proper frame of reference, the plasma rest frame, by correcting the Doppler shift. In the upstream region the dispersion relation exhibits two branches which correspond to the right-hand polarized magnetosonic/whistler mode and the ion beam resonant mode, respectively. The upstream waves exhibit phase velocities oriented toward upstream along the magnetic field in the plasma rest frame. In the downstream region the dispersion relations show a transition to the mirror mode whose properties are frequently detected in the statistical study, too. Interestingly, the mirror modes have finite propagation speeds, possibly coupled to the background inhomogeneities known as the drift mirror mode. While the upstream waves propagate nearly parallel to the background magnetic field, the downstream waves propagate nearly perpendicular. On a statistical average there is an organization of wave propagation pattern: outward divergent in the upstream region; toward the magnetosheath flank region aligned with the plasma flow direction in the downstream region; and inward convergent in the magnetosheath flank. The wave number spectra are also directly determined for the magnetic field fluctuations in the shock upstream region and they are interpreted in light of turbulence. The fluctuations exhibit properties of not fully developed turbulence but intermittency, suggesting that there is not enough time for turbulence to become fully developed.Die CLUSTER-Raumsondemission ermöglicht erstmals Messungen an vier Raumpunkten im erdnahen Weltraum, damit man nicht nur Wellenvektoren, sondern auch Dispersionsrelationen und Ausbreitungsmuster der Wellen sowie Eigenschaften der Turbulenz nahe der Bugstoßwelle der Erde bestimmen kann. Außerdem können solche Eigenschaften durch die Berechnung der Doppler-Verschiebung im richtigen Rahmen, Plasma-Ruhesystem, dargestellt werden. Die Dispersionsrelationen im Upstream-Gebiet (vor der Bugstoßwelle) zeigen zwei Kurven, die der rechthändige zirkular polarisierte Mode und der Ionenstrahl-resonante Mode entsprechen. Im Downstream-Gebiet (hinter der Bugstoßwelle) zeigen die Dispersionsrelationen eine Kurve, die der Mirror-Mode entspricht. Die Eigenschaften der Mirror-Mode ist statistisch am häufigsten im Downstream-Gebiet beobachtet. Interessanterweise zeigen die Mirror-Mode eine endliche Ausbreitungsgeschwindigkeit. Die Mirror-Mode mag also mit der räumlichen Inhomogenetät gekoppelt werden. Während die Upstream-Wellen sich parallel zum Magnetfeld nach außen von der Erde ausbreiten, breiten sich die Downstream-Welle senkrecht zum Magnetfeld und nach innen zur Erde aus. Wellenzahlspektren im Upstream-Gebiet werden auch direkt bestimmt, und die Fluktuationen werden vom Blickwinkel der Turbulenz interpretiert. Die Upstream-Wellen stellen die Eigenschaften der intermittenten Turbulenz dar, d.h. das Upstream-Gebiet hat keine Zeit, um voll entwickelte Turbulent zu werden

Some potential precursor routes to aromatic polyesters via quinone methides

Poly(para-hydroxybenzoic acid) [pHBA] was discovered in the late 1950s and found to have chemical and mechanical properties which make it attractive for use as a high-performance polymer, potentially in engineering applications. However, the same properties make it difficult to fabricate into films or fibres. This thesis examines the philosophy of the precursor approach to intractable polymers as applied to the synthesis of aromatic polyesters generally and to pHBA specifically, by means of a review on the production of benzene derivatives by ring synthesis, and the polymerisation of 1,4-benzoquinone methides. Work undertaken includes the synthesis and characterisation of a precursor to 7,7-dichloro-1,4-benzoquinone methide, endo-cis-6-dichloromethylenetricyclo[6.2.1.0(^2,7)]undeca-4,9-dien-3-one, and the assignments of the (^1)H and (^13)C NMR spectra of endo-cis-6,6-dimethoxytricyclo- [6.2.1.0(^2,7)]undeca-4,9-dien-3-one (a correction to the published assignment) and its intramolecular 2+2 photocycloaddition product, 8,8-dimethoxypentacyclo- [8.1.0(^1,5).0(^2,9).0(^4,7).0(^6,10)]undecan-3-one