Please read the abstract in the front section of this document / Dissertation (MChD (Periodontics and Oral Medicine))--University of Pretoria, 2007. / Oral Pathology and Oral Biology / unrestricted

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A ramjet inlet duct structure has been designed using nonlinear structural analysis to allow local plastic deformations which result in structural weight reduction. To establish the feasibility of reduced shell thickness, the Lower-Bound Theorem of limit analysis has been applied using an existing finite element analysis computer code intended for elastic analysis. The results of the analysis were verified by structural testing. Predicted stresses and deflections showed good correlation with measured values up to the point of failure. This work was supported by the U.S. Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio, under Contract No. F33615-72-C-1366.

Exploratory data analysis aims to study datasets through the use of iterative, investigative, and visual analytic algorithms. Due to the difficulty in managing and accessing the growing volume of unstructured data, exploratory analysis of datasets has become harder than ever and an interest to data mining researchers. In this dissertation, we study new algorithms for exploratory analysis of data collections using clusters and stories. Clustering brings together similar entities whereas stories connect dissimilar objects. The former helps organize datasets into regions of interest, and the latter explores latent information by connecting the dots between disjoint instances. This dissertation specifically focuses on five different research aspects to demonstrate the applicability and usefulness of clusters and stories as exploratory data analysis tools. In the area of clustering, we investigate whether clustering algorithms can be automatically "alternatized" and how they can be guided to obtain alternative results using flexible constraints as "scatter-gather" operations. We demonstrate the application of these ideas in many application domains, including studying the bat biosonar system and designing sustainable products. In the area of storytelling, we develop algorithms that can generate stories using distance, clique, and syntactic constraints. We explore the use of storytelling for studying document collections in the biomedical literature and intelligence analysis domain. / Ph. D.

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Dental implant guidance systems promise precise placement, but postoperative assessment with CBCT scans poses radiation risks. This study utilizes an optical scanning method to evaluate implant placement position and assess the accuracy of robotic assistance using the Neocis Yomi system. METHODS: In a longitudinal study at Boston University, Robotic-assisted dental implant Placement was evaluated. The test population excluded fully edentulous patients. The current cohort focused on eight patients: four were fully guided, and four were partially guided. Optical impressions were obtained with a CEREC Omnicam scanner and indexed using ELOS-accurate Scan Bodies. The preop virtual placement plan was merged with the actual post-op implant placement and then analyzed with Geomagic Control X software to measure deviations between planned and executed positions. RESULTS: In the four Fully guided patients, the deviation of the Implant at the platform level, midpoint, and apex was 1.3133mm, 1.4425mm, and 1.4355mm, respectively. In the four partially guided patients, the implant deviation at the platform, midpoint, and apex was 1.691mm, 1.0291mm, and 2.2226mm. CONCLUSION: Despite the study limitations, robotically assisted implant surgery demonstrates accuracy comparable to traditional guidance systems. The use of Intraoral optical scan bodies provides a radiation-free evaluation of the as planned vs. executed dental implant placement. This method should be adopted for future research.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis entails the stages of the development of an arterial catheter capable of being guided by the impedance of human tissue. Such a device would be desired in cases where it is not possible to locate the artery of a patient using anatomical landmarks. This design thus aims to improve the accuracy of first time placement of arterial catheters. The thesis entails the literature study done in order to initiate the development of said device, followed by preliminary concept design and evaluation. The thesis also contains a description of all experimental phases, done on in vitro tissue samples, in vivo samples in living porcine subjects and in vivo samples in living human patients. Experiments were performed to determine if any repeatable noticeable difference in tissue impedance could be identified and utilized in the hope of guiding this device using acquired differences in tissue impedance. The different stages of development for the prototype used in these tests are also described in detail. In addition, the results of the different tests are presented, which prove that there is a significant difference between blood tissue impedance and the surrounding tissue types encountered, allowing for guidance of the proximal tip of the arterial catheter, based on the tissue impedance measured. Finally, the thesis entails a description of further work which could be performed if this concept were to be considered as a marketable product. / AFRIKAANSE OPSOMMING: Hierdie tesis behels die verskillende stappe in die ontwerp van 'n kateter wat deur middel van die verskillende impedansie vlakke van biologiese weefsel gelei kan word in die menslikke liggaam. Sò ‘n toestel sal behulpsaam wees in gevalle waar plasing nie gedoen kan word met die behulp van anatomiese landmerke nie. Hierdie ontwerp mik dus om die akkuraatheid van die plasing van kateters te verbeter. Die tesis behels die literatuur studies benodig om sò 'n toestel te ontwerp, gevolg deur voorlopige konsep ontwerpe en die evaluasie van hierdie konsepte. Die tesis behels ook die verskillende eksperimentele fases van die projek; eksperimente op in vitro weefsel monsters, in vivo diere toetse en in vivo kliniese toetse op menslike weefsel. Al hierdie eksperimente is gedoen om te bepaal of enige herhaalbare, waarneembare verskil in weefsel impedansie geidentifiseer kan word en dus gebruik word met die hoop om diè teoretiese kateter te lei met behulp van diè verskil in weefsel impedansie. Die verskillende stappe van die ontwerp van die prototipes gebruik in hierdie eksperimente word ook in detail beskryf. Die resultate van die verskillende eksperimente word ook aangebied, wat bewys dat daar 'n beduidende verskil is tussen die impedansie van bloed weefsel en die impedansie van die aanliggende weefsel tipes, wat dus impliseer dat die proksimale punt van die kateter gelei kan word deur die gemete impedansie by die punt van die toestel, gebaseer op die resultate wat gevind is. Laastens behels die tesis ook 'n beskrywing van toekomstige werk wat gedoen kan word indien die konsep ontwikkel word tot 'n bemarkbare produk.