No matter how inspection techniques have been advanced, manual visual inspection is currently still the first and fundamental step in assessing civil infrastructure. If no sign of deterioration has been spotted in manual inspection, any future inspection actions is not necessary to take. However, manual inspection has been identified with several limitations including the qualitative nature of inspection results, the time-consuming inspection process, and the heavy reliance on inspectors' and/or engineers' experience. In order to overcome these limitations, automated visual inspection systems have been proposed to enhance and/or replicate the manual inspection process. A number of image processing methods have been developed in detecting defects (i.e. coating rusts) and damage (i.e. cracks) on civil infrastructure. Their effectiveness has been verified in inspecting structures, such as bridges, underground pipes, and tunnels. Although existing methods are effective in finding defects and damage from digital images, missing two important links limits their application for rapid infrastructure assessment and rehabilitation. The first link is the correlation between the defects/damage and the structural members that the defects/damage lie on. The second link is the relationship between the defects/damage and their impacts on the structural members. The purpose of this research is to investigate the way of establishing these two links. It is focused on the retrieval of critical structural members and defects/damage information from images/videos, and then the utilization of this information for automated and rapid assessment and rehabilitation of civil infrastructure. Specifically, a combination of techniques from the areas of visual pattern recognition, digital filtering, and machine vision have been used in order to develop a set of methods for concrete column recognition, crack properties retrieval, and air pockets and discoloration detection and evaluation. The methods proposed in this research were implemented in a Microsoft Visual Studio environment, and tested on the real images/videos of concrete structures inflicted with cracks, air pockets and discoloration. The test results indicated that the methods could automatically recognize concrete columns, correctly measure the properties of the cracks in a crack map, and accurately evaluate the impacts of air pockets and discoloration on the visual quality of concrete surfaces.

Master of Agribusiness / Department of Agricultural Economics / Ted C. Schroeder / The CNH Wichita Product Center has had a chronic leak problem with the Skid Steer Loaders. The objective of this project was to analyze the manufacturing plant leak data and make improvements to correct the issue. The objective is twofold: 1) to make process or design improvements on current products produced in the plant and 2) to make recommendations for future designs to prevent such leak issues from reoccurring. The manufacturing data had to be transformed into usable form and then it was analyzed mostly by utilizing Pareto Charts. The highest six problem leak points were chosen from the manufacturing data. Process changes were implemented on these particular leak joints and the results were analyzed using two proportions hypothesis tests. The process changes reduced the leak rate by an average percent reduction of 86 percent. The process changes implemented will also be applied to other similar joints, and results documented in the future. The future design recommendations made from the analyzed data included the increased use of o-ring face seal connections at certain locations and where possible, reducing the number of joints per machine.

After hot rolling, the presense of segregation in the center of wire-rod can lead to a nonuniform transformation, resulting in bands of martensite in the microstructure. This is considered to be a defect, called center-martensite, because it can cause cracks and breaks during wire drawing. To identify the mechanism for the formation of center-martensite in wire-rod, the structure, macrosegregation and microsegregation in unworked billets were characterized. Based on measurements of secondary dendrite arm spacings, cooling rates during solidification were estimated. It appears that the macrosegregation of carbon and manganese in the billets manifests itself as the microsegregation in wire-rod, which is an agent in forming the center-martensite. Thus, electromagnetic stirring is proposed as a means to reduce the macrosegregation in the billet and, thereby, reduce the occurrence of center-martensite in wire-rod.

Most current commercial automated IC inspection systems use gray-level or binary images for IC defect detection in spite of the fact that color permits defect detection where gray-level information is insufficient. Three color image processing techniques including the spectral-spatial clustering, principal components, and hue-saturation-value (HSV) color features have been investigated to evaluate the usefulness of color for IC defect detection. The AMOEBA spectral-spatial clustering algorithm, an un-supervised color segmentation approach, with a sequence of image processing procedures resulted in segmentation results with high accuracy and discriminated successfully an isolated and homogeneous defect with an unique color signature. The principal components transformation and the HSV color features, two color enhancement/separation algorithms, have proven useful for enhancing and isolating weak spectral signatures in the defect regions. The results of this investigation into the use of color are promising.

Single ventricle heart defects are present in two of every 1000 live births in the US. In this condition the systemic and pulmonary blood flow mix in the functioning ventricle, resulting in insufficient blood oxygenation to sustain life. As part of the palliation of these defects, the staged surgical procedure, known as the Fontan procedure, is performed. Here, the venous returns are directed to the pulmonary arteries, bypassing the right heart and forming the Total Cavopulmonary Connection (TCPC). Even though the palliation improves life expectancy, there are numerous long-term complications that become more prevalent as patients reach adulthood. Many of these complications have been related to the function of the single ventricle circulation, especially to the abnormal TCPC hemodynamics, for which this has been the focus of research throughout the years. Recent progress has been made with the availability of improved medical imaging techniques and computational modeling tools; however, there is limited information on how these evolve in time. In order to improve the Fontan palliation, image-based surgical planning has been used in the most complex cases to prospectively design the TCPC, aiming to improve the hemodynamics. Even though this paradigm has shown promising results, improvement is needed to provide more realistic predictions of the post-operative outcomes. To address this, in this thesis we have developed a novel surgical planning framework that allows us to: (i) model the interaction of the TCPC and global circulation hemodynamics, and (ii) assess the robustness of the surgical option proposed. Here, the single ventricle circulation is modeled using a lumped parameter model, coupled to a computational fluid solver to describe the local TCPC hemodynamics. With this framework, we can predict the immediate post-operative state, model various physiological scenarios, and assess the impact on the local hemodynamics and global circulation. This will allow us to provide information on the effect on the global hemodynamics to the clinical team. In addition to the surgical planning advancements obtained in this thesis, we have performed the largest longitudinal Fontan study to date in which we have evaluated the evolution of the Fontan physiology in time and the effect it has on the energy efficiency of the TCPC. In this thesis, we have studied the short and long-term effects that geometrical and physiological changes have on the Fontan hemodynamics. With this, we have improved the understanding of the Fontan physiology in terms of the short-term effects of Fontan palliation and the long-term deterioration of the changing single ventricle physiology.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Long term performance of a road pavement structure is significantly influenced by its potential to distribute traffic loading from the surface to the natural subgrade. The interlayer adhesion conditions play a substantial role in the induced stress-strain distribution across all layers of the entire structure. For layers constructed in stages like a granular base (GB) and a cement treated subbase (CTSB), the state of adhesion is questionable. Therefore a detailed investigation on the achievable adhesion and its influence on pavement performance is essential. In this study, the direct shear test was used to assess the interlayer adhesion strength in terms of resistance of the GB layer to slide on top of the CTSB. To evaluate the level of achieved shear strength, the interlayer shear results were compared to the inlayer strength for a granular base and cemented subbase. The shear test results were presented in terms of relationships between shear stress and displacement, shear stress and normal pressure and vertical and horizontal displacements. Based on frictional and dilatant approaches, shear test results demonstrated that the interlayer adhesion strength between the GB and CTSB is significantly influenced by the roughness conditions of the CTSB before placing the GB. Compacting materials of the base layer on top of the scarified CTSB produces a unified compound structure due to intimate interaction between the two layers. Moreover, the achievable adhesion depends on the maximum grain size available in the CTSB layer, confining pressure and moisture condition. The increase in maximum aggregate size deepens the interaction zone between the GB and scarified CTSB which results in high shear resistance. Ingress of water induces lubricant behaviour and weakens the shear resistance. In the design example, it was shown that the assumption of full adhesion between pavement layers, currently used in many design methods, over-estimates the pavement life. The routine construction process of placing the GB on top of quasi-smooth CTSB induces poor adhesion between the layers which therefore affects stress-strain distribution behaviour across all layers of the pavement structure and then reduces the life of every single layer. According to the design example, the granular base layer is the most susceptible to early failure due to its stress-dependent behaviour. The significant difference between pavement life when full adhesion is considered and when partial adhesion is allowed indicates that the achievable adhesion should be considered during the design of the structure rather than assuming full adhesion. Furthermore, the development of practical specifications and technical guidelines for improving the anticipated conditions in the field is recommended. / AFRIKAANSE OPSOMMING: Die langtermyngedrag van 'n plaveiselstruktuur word tot 'n groot mate beïnvloed deur die vemoë daarvan om om verkeerslaste vanaf af die oppervlakte na die natuurlike grondlaag te verprei. Die adhesie tussen die plaveisellae speel 'n belangrike rol in die verspreiding van spannings en vervormings deur al die lae van die struktuur. In lae wat in fases gebou word, soos 'n grofkorrelrige kroonlaag (GB) en 'n sementgestabiliseerde stutlaag (CTSB), is die adhesie onder verdenking. 'n Detailondersoek van die adhesie wat behaal kan word, en die invloed daarvan op plaveiselgedrag, is daarom noodsaaklik. In hierdie ondersoek is die direkte skuiftoets gebruik om die tussenlaag-adhesie vas te stel in terme van die weerstand van die GB-laag om oor die CTSB-laag te skuif. Om die vlak van skuifsterkte wat behaal kan word, te bepaal, is die tussenvlakskuifsterkte vergelyk met die interne skuifweerstand van die grofkorrelrige laag en van die gestabiliseerde laag. Die skuiftoetsresultate is uitgedruk in terme van die verbande tussen skuifspanning en skuifverplasing, tussen skuifspanning en normaalspanning en ook tussen vertikale en horisontale verplasings. Gebaseer op skuifweerstand en dilatansie het skuitoetsresultate gedemonstreer dat adhesie tussen die GB- en CTSB-lae baie beïnvloed word deur die ruheid van die CTSB voordat die GB gebou word. Indien die GB-laag bo-op 'n grofgemaakte CTSB-laag geplaas word, word 'n baie goeie verband en interaksie tussen die twee lae verkry. Die beskikbare adhesie hang ook af van die maksimum korrelgrootte in die CTSB-laag, die inperkspanning en die waterinhoud. Die toename in maksimum aggregaatgrootte maak die interaksiesone tussen die GB en die grofgemaakte CTSB dieper en dit lei tot hoër skuifweerstand. Infiltrasie van water dien as smeermiddel wat die weerstand verlaag. In die ontwerp-voorbeeld is gedemonstreer dat die aanname van volle adhesie tussen plaveisellae, soos wat tans in baie ontwerpmetodes gedoen word, tot oorskatting van die leeftyd van die plaveisel lei. Die normale konstruksiemetode waarin die GB-laag bo-op 'n semi-gladde CTSB-laag geplaas word, lei tot swak adhesie tussen die lae wat verspreiding van spannings en vervormings deur die plaveisel minder gunstig maak en die leeftyd van alle lae in die plaveisel verlaag. Volgens die ontwerp-voorbeeld is die grofkorrelrige kroonlaag die vatbaarste vir voortydige faling as gevolg van die sy spannings-vervormingsgedrag. Die beduidende verskil tussen plaveiselleeftyd wanneer volle adhesie aanvaar of slegs gedeeltelike adhesie toegelaat word, illustreer dat die werklike haalbare adhesie gebruik moet word eerder as om volle adhesie te aanvaar. Verder word die onwikkeling van praktiese spesifikasies en tegniese riglyne om die verwagte toestande in die plaveisel beter in ag te neem, voorgestel.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy