published_or_final_version / abstract / Applied Geosciences / Master / Master of Science

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Gyroscopic stabilization can be used to maintain an otherwise unstable body in an upright position. Devices equipped with gyroscopes can balance upon a small area or point without falling over when the gyroscopic stabilizing force is greater than a rotational force or moment from an out-of-balance load that causes the device to tip. A new concept for a gyroscopically stabilized platform has been proposed in the form of a schematic diagram. The proposed system comprises of four interconnected gyroscopes that react to the tipping of an inherently unstable external body. The purpose of this research is to evolve a design for, and establish the feasibility of building the proposed stable platform using available materials and technology. If feasible, the gyroscopically stabilized platform will be made at the most practical and economic size. Louis Brennan developed a 37 tonne monorail that was maintained in the upright position with two 3 tonne counter rotating gyroscopes. The Brennan monorail is analysed to better understand the behaviour of a similar coupled gyroscopic stabilization system. The reactions between the components that maintain the monorail in the stable position are studied and comparisons are made between the proposed stable platform and the Brennan system. A mathematical analysis of the proposed system is presented. The equations of motion for the system are derived using the Lagrangian Formalism. The characteristic equation of the system is then determined and from this a set of stability conditions imposed on the design of the physical parameters of the stable platform. The general solutions to the equations of motion are then derived. Expressions that model the behaviour of two of the variables that describe the motion of the stable platform are determined. A systematic approach is adopted for establishing a new concept for the proposed system. Testing of the initial stable platform prototype (Prototype A) showed the system did not behave as intended. The platform was optimised further and this resulted in a second prototype, Prototype B. Prototype B exhibiting the desired oscillatory motion about the vertical of the platform. Predictions made using the mathematical model are compared with empirical results. The mathematical model was found to be an accurate method for predicting the response of the stable platform.

CSLIP2 (De Natale, 1987) is the only slope stability program that utilizes a "direction set" optimization routine in its search for the minimum safety factor. However, CSLIP2 which employs Powell's Conjugate Direction Method permits only the horizontal and vertical directions (x and y) to be used as the initial direction set. The efficiency of the existing search routine is improved by replacing the x-y coordinate directions with initial directions that are parallel to and perpendicular to the principal axis of the safety factor contours.

Recording a video sequence with a camera during movement often produces blurred results. This is mainly due to motion blur which is caused by rapid movement of objects in the scene or the camera during recording. By correcting for changes in the orientation of the camera, caused by e.g. uneven terrain, it is possible to minimize the motion blur and thus, produce a stabilized video. In order to do this, data gathered from a gyroscope and the camera itself can be used to measure the orientation of the camera. The raw data needs to be processed, synchronized and filtered to produce a robust estimate of the orientation. This estimate can then be used as input to some automatic control system in order to correct for changes in the orientation This thesis focuses on examining the possibility of such a stabilization. The actual stabilization is left for future work. An evaluation of the hardware as well as the implemented methods are done with emphasis on speed, which is crucial in real time computing. / En videosekvens som spelas in under rörelse blir suddig. Detta beror främst på rörelseoskärpa i bildrutorna orsakade av snabb rörelse av objekt i scenen eller av kameran själv. Genom att kompensera för ändringar i kamerans orientering, orsakade av t.ex. ojämn terräng, är det möjligt att minimera rörelseoskärpan och på så sätt stabilisera videon. För att åstadkomma detta används data från ett gyroskop och kameran i sig för att skatta kamerans orientering. Den insamlade datan behandlas, synkroniseras och filtreras för att få en robust skattning av orienteringen. Denna orientering kan sedan användas som insignal till ett reglersystem för att kompensera för ändringar i kamerans orientering. Denna avhandling undersöker möjligheten för en sådan stabilisering. Den faktiska stabiliseringen lämnas till framtida arbete. Hårdvaran och de implementerade metoderna utvärderas med fokus på beräkningshastighet, som är kritiskt inom realtidssystem.

Present day society generates large volumes of waste that present an environmental hazard when disposed of in landfills. As our population grows, so does the volume of waste generated and hence the threat to our environment. One method of reducing harmful emissions in landfills is the mechanical-biological pretreatment of waste prior to landfilling. The purpose of this dissertation is to investigate the degree of stabilization of waste in shallow landfills (simulated by test cells) with particular focus on biogas production and quality. Municipal waste was composted in aerobic, open windrows for periods of eight and sixteen weeks. Five test cells, designed and operated according to the PAF model (Pretreatment, Aeration and Flushing) were constructed at the Bisasar Road landfill site. These cells were used to simulate large scale municipal landfill sites. They were filled with fresh and pretreated waste and were used to monitor the dynamics of prolonged aeration and degradation of waste over a period of six months. The cells were monitored on a weekly basis while being aerated. Two flushing events were conducted at the beginning of the passive aeration. Gas emissions were also monitored by recording the methane, carbon dioxide and oxygen volumes per volume of air in probes strategically placed in each cell. These results were then analysed to assess the effect of mechanical-biological pretreatment of municipal solid waste on the emission quality of sanitary landfills and the appropriateness of prolonging the aeration in shallow landfills, as often used in sub-tropical countries. It was found that the design of the test cells was appropriate for the landfilling and stabilization of waste that was aerobically treated. After six months in the test cells, analysis of the waste from each cell showed that the waste was completely degraded. The PAF model, when applied to shallow landfills, is very effective in stabilising waste and would be appropriate for a sub-tropical climate. Waste that is pretreated, placed in shallow landfills, initially flushed and then aerated over a six month period was fully stabilized. The requirement for such treatment would be relatively small amounts of waste, a wet climate and the availability of open space for shallow landfills. This method, therefore, would be very appropriate in a South African context. The major problem with this method may be the generation of large quantities of leachate which will have to be treated and disposed of in an environmentally safe manner. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.

Cell-type specific dendritic morphologies emerge via complex growth mechanisms modulated by intrinsic and extrinsic signaling coupled with activity-dependent regulation. Combined, these processes converge on cytoskeletal effectors to direct dendritic arbor development, stabilize mature architecture, and facilitate structural plasticity. Transcription factors (TFs) function as essential cell intrinsic regulators of dendritogenesis involving both combinatorial and cell-type specific effects, however the molecular mechanisms via which these TFs govern arbor development and dynamics remain poorly understood. Studies in Drosophila dendritic arborization (da) sensory neurons have revealed combinatorial roles of the TFs Cut and Knot in modulating dendritic morphology, however putative convergent nodal points of Cut/Knot cytoskeletal regulation remain elusive. Here we use a combined neurogenomic, bioinformatic, and genetic approach to identify and molecularly characterize downstream effectors of these TFs. From these analyses, we identified Formin3 (Form3) as a convergent transcriptional target of both Cut and Knot. We demonstrate that Form3 functions cell-autonomously in class IV (CIV) da neurons to stabilize distal higher order branching along the proximal-distal axis of dendritic arbors. Furthermore, live confocal imaging of multi-fluor cytoskeletal reporters and IHC analyses reveal that form3 mutants exhibit a specific collapse of the dendritic microtubule (MT) cytoskeleton, the functional consequences of which include defective dendritic trafficking of mitochondria and satellite Golgi. Biochemical analyses reveal Form3 directly interacts with MTs via the FH1/FH2 domains. Form3 is predicted to interact with two alpha-tubulin N-acetyltransferases (ATAT1) suggesting it may promote MT stabilization via acetylation. Analyses of acetylated dendritic MTs supports this hypothesis as defects in form3 lead to reductions, whereas overexpression promotes increases in MT acetylation. Neurologically, mutations in Inverted Formin 2 (INF2; the human ortholog of form3) have been causally linked to dominant intermediate Charcot-Marie-Tooth (CMT) disease E. CMT sensory neuropathies lead to distal sensory loss resulting in a reduced ability to sense heat, cold, and pain. Intriguingly, disruption of form3 function in CIV nociceptive neurons results in a severe impairment in nocifensive behavior in response to noxious heat, which can be rescued by expression of INF2 revealing shared primordial functions in regulating nociception and providing novel mechanistic insights into the potential etiological bases of CMT sensory neuropathies.