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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Methods for measuring environmental disturbances affecting residents and pedestrians - a contribution to rail project appraisal

Hopkinson, P. G. January 1988 (has links)
No description available.

Energy absorption characteristics and assessment of failure criteria during ship collisions

Glykas, Alexandros January 1998 (has links)
No description available.

Polarisation correlation studies of the 3D states of helium

McLaughlin, Damien T. January 1992 (has links)
No description available.

Small specimen impact testing and modelling of carbon fibre T300/914

Hallett, Stephen Richard January 1997 (has links)
No description available.

Mechanical behaviour of materials at high rates of strain : a study of the double notch shear test

Ruiz, Daniel John January 1990 (has links)
No description available.

Cumulative effects assessment in the UK : progress and potential

Piper, Jacqueline Melissa January 2000 (has links)
No description available.

Origin of strong lunar magnetic anomalies: Further mapping and examinations of LROC imagery in regions antipodal to young large impact basins

Hood, Lon L., Richmond, Nicola C., Spudis, Paul D. 06 1900 (has links)
The existence of magnetization signatures and landform modification antipodal to young lunar impact basins is investigated further by (a) producing more detailed regional crustal magnetic field maps at low altitudes using Lunar Prospector magnetometer data; and (b) examining Lunar Reconnaissance Orbiter Wide Angle Camera imagery. Of the eight youngest lunar basins, five are found to have concentrations of relatively strong magnetic anomalies centered within 10° of their antipodes. This includes the polar Schrödinger basin, which is one of the three youngest basins and has not previously been investigated in this context. Unusual terrain is also extensively present near the antipodes of the two largest basins (Orientale and Imbrium) while less pronounced manifestations of this terrain may be present near the antipodes of Serenitatis and Schrödinger. The area near the Imbrium antipode is characterized by enhanced surface thorium abundances, which may be a consequence of antipodal deposition of ejecta from Imbrium. The remaining three basins either have antipodal regions that have been heavily modified by later events (Hertzsprung and Bailly) or are not clearly recognized to be a true basin (Sikorsky-Rittenhouse). The most probable source of the Descartes anomaly, which is the strongest isolated magnetic anomaly, is the hilly and furrowed Descartes terrain near the Apollo 16 landing site, which has been inferred to consist of basin ejecta, probably from Imbrium according to one recent sample study. A model for the origin of both the modified landforms and the magnetization signatures near lunar basin antipodes involving shock effects of converging ejecta impacts is discussed.

Soil classification through dynamic soil signatures

Yeow, Hoe Chian January 1990 (has links)
The demand for a cost effective site investigation method has resulted in the introduction of various advanced in-situ testing techniques. These techniques utilise modern electronics instrumentation to monitor various soil parameters during site investigation. The data is then processed using high speed, low cost digital computers which allow an accurate and rapid assessment of the conditions of the foundation soil under a proposed construction site. In this thesis, a site investigation tool that drives a coring tube into the ground under a combination of vibration and impact is considered. This machine, called a vibro-impact corer, is fully instrumented to provide penetrometer-type information and a core sample for further inspection in the laboratory. The self-adjusting mechanism inherent in this machine delivers the minimum level of energy required to overcome soil resistance which thereby allows continuous penetration of the coring tube. This mechanism is also results in minimal induced disturbance during the coring process. This thesis investigates use of the vibro-impact corer as a soil classification tool. It involves the design of data analysis software to perform the soil classification procedure. Due to the nature of the system, the resistance monitored through the annular load cell fitted at the tip of the coring tube consists of the dynamic end resistance waveform and the peak magnitude of these waveforms over a sampling period. The vibro-impact soil classification system is based on the distinct self-adjusting mechanism of the machine. The self-adjustment mechanism imparts a different level of impact and vibration as soil conditions change which produces distinct dynamic soil resistance waveforms. In addition, the penetration rate and the magnitude of the soil resistance encountered also varies according to the material being penetrated. These two features are used to form the basis of the soil classification system in this software. The software also includes options for empirical correlation of the results obtained from the vibro-impact penetrometer with the CPT and SPT tests to allow comparison. The vibro-impact soil classification software is designed to be user-friendly. It reads the data files from a Biodata Transient Capture System for the classification process. The output devices such as plotter and printer are used to produce hardcopy records for various data. All the options are menu driven. A two degree freedom simulation of the operational responses of the vibro-impact machine is also included in this thesis. The main objective of this simulation is to study the soil response during vibro-impact mode of driving. This allows a comparison of the simulation soil responses to the model test results to provide an understanding of the soil behaviour under a combination of both vibratory and impact loadings. This thesis presents the results of several laboratory model and full scale vibro-impact penetrometer tests. It concentrates on the main subject of soil classification during the discussions although in some occasions the operational mechanism of the machine is mentioned. The results justify the approaches adopted for the soil classification system using a vibro-impact machine.

Effective impact prediction: how accurate are predicted impacts in EIAs?

Molefe, Noella Madalo January 2017 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017. / An Environmental Impact Assessment (EIA) is an instrument used to limit unexpected and negative effects of proposed developments on the environment. Much experience has been gained internationally but the lack of follow-up after the EIA is prepared is one of the major weak spots of the assessments. It is therefore very important to follow up on development projects and observe their effects on the environment after the go-ahead has been given, so that the EIA quality may be improved. There is often a significant difference between predicted impacts and actual impacts. Sometimes the predicted impacts do not occur, or new impacts which were not predicted in the Environmental Impacts Assessment Reports (EIRs) arise. The aim of this study was to assess the accuracy of the impacts predicted in the EIRs compiled for three large-scale Eskom projects currently under execution situated in the Mpumalanga, Limpopo and KwaZulu-Natal provinces by comparing them to the actual impacts that occurred on site. The EIA follow-up process was used to assess the influence that the EIA may have on large-scale projects and ultimately assess the effectiveness of the EIA process as a whole. A procedure developed by Wilson (1998) was used to follow up on the selected projects because the method allowed for comparisons between the actual and predicted impacts to be made and for discrepancies in the EIRs to be identified. Recent audit reports, aerial photographs and interviews were all used to identify actual impact occurrence. Of the impacts which actually occurred, 91% occurred as predicted (OP) and 9% occurred but were not predicted (ONP). The majority of impacts omitted from the reports were hydrological (27%) and air quality impacts (25%). These unexpected impacts were most probably overlooked because they are site-specific, temporary in nature and would not cause any significant environmental damage. Of all the impacts predicted in the reports, 85% were accurately predicted and 15% were not. The impacts inaccurately predicted were hydrological impacts (27%), flora and fauna impacts (7%) and 30% other impacts which included soil pollution, fires and loss of agricultural potential. The inaccuracies could be a result of Environmental Impact Assessment Practitioners (EAPs) predicting a large number of impacts with the hopes of lowering the risk of omitting impacts. However, sometimes the impacts predicted do not occur in reality. Overall it can be concluded that the impact prediction accuracy of the three EIRs compiled for Eskom exceeds previous studies conducted nationally. Eskom EIRs are highly accurate with regards to impact prediction with minor discrepancies which can easily be rectified. Key words: Environmental Impacts Assessment (EIA) Environmental Impacts Assessment Reports (EIRs), Environmental Impact Assessment Practitioners (EAPs), EIA follow-up, discrepancies. / LG2017

Analysis of three genes that contribute to fibrosis in South African systemic sclerosis patients

Frost, Jacqueline Michelle 14 September 2010 (has links)
MSc (Med), Faculty of Health Sciences, University of the Witwatersrand / Introduction: Systemic sclerosis (SSc) is a complex autoimmune disease characterised by autoantibody release, leading to microvascular injury, fibroblast activation and increased production of collagen. The genetics of SSc is complex with many genes implicated in the development and maintenance of the extracellular matrix (ECM). The main aim of this study was to test for differential expression of matrix metalloproteinase 1 (MMP1), tissue inhibitor of metalloproteinase 1 (TIMP1) and hepatocyte growth factor (HGF) in SSc patients compared to healthy control individuals and to assess whether the differential expression of these genes could have an impact on clinical features of the disease. Methods: Two skin biopsies were analysed for each of 16 black SSc patients, one from clinically involved skin (lateral forearm) and one from clinically uninvolved skin (back). One skin sample was obtained from 15 ethnically matched control individuals. The differential expression of MMP1, TIMP1 and HGF in the clinically involved and uninvolved patient samples would be compared to control individuals using relative quantification polymerase chain reaction (qPCR). The gene expression profiles were then compared to specific clinical features to deduce whether any of the gene expression profiles is correlated with the manifestation of specific clinical features. Results: MMP1 gene expression was significantly decreased in SSc patients for both involved (p=0.0004) and uninvolved skin (p=0.0004) compared to controls. Conversely, TIMP1 gene expression was significantly increased in SSc patients at both sites compared to controls (p=<0.00001 for both comparisons). A trend of significance was observed for the difference in TIMP1 expression between the involved an uninvolved skin within the patients (p=0.05) with a greater increase in involved skin. HGF had increased gene expression in the patients compared to controls for involved and uninvolved skin (p=0.002 and 0.004, respectively). The difference in gene expression between the involved and uninvolved biopsies was not significant for either MMP1 or HGF (p=0.87 and 0.83, respectively). The only correlates that may have a biological significance are HGF in involved skin correlated with disease activity (r=0.60; p=0.013) and HGF in uninvolved skin vi correlated with skin score (MRSS) with r=0.50 and p=0.048. With regards to the categorical data, two marginally significant observations were found, once again with HGF, which was found to be associated with gender in involved skin (p=0.037) and renal disease in uninvolved skin (0.031). Conclusion: The relative under expression of MMP1 and over expression of TIMP1 reflect the pro-fibrotic state of scleroderma skin. The over expression of HGF suggests that HGF may play a compensatory anti-fibrotic role, although this is not sufficient to overcome the pro-fibrotic state of the skin. This study provides supporting evidence to debunk the myth of uninvolved skin in SSc patients. The altered expression of MMP1, TIMP1 and HGF in the clinically uninvolved skin of SSc patients suggests that all subcutaneous tissue is affected, although to a greater extent in the clinically involved skin of the patients.

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