A consequence of high speed rail transportation is the generation of elevated ground borne vibrations. This thesis presents several original contributions towards the prediction of these vibrations. Firstly, a new three dimensional finite element model capable of vibration prediction was developed. Its main feature was its ability to model complex track geometries while doing so through a fully coupled vehicle-tracksoil system. Model output was compared to experimental results obtained during this thesis and also to independent data sets. It was shown to predict velocity time histories, vibration frequency spectrums and international vibration descriptors with high accuracy. An appraisal of the suitability of a finite difference time domain modelling approach for railway vibration prediction was also undertaken. This resulted in the development of a new ‘higher order’ perfectly matched layers absorbing boundary condition. This condition was found to offer higher performance in comparison to current alternative absorbing boundary conditions. Field work was then undertaken on high speed lines with varying embankment conditions in Belgium and England. Vibration data was recorded up to 100m from each track and geophysical investigations were performed to determine the underlying soil properties. The results were used for numerical model validation and also to provide new insights into the effect of various embankment conditions on vibration propagation. It was found that embankments generate higher frequency excitation in comparison to nonembankment cases and that cuttings generate higher vibration levels than noncuttings. Once validated the finite element model was used to provide new insights into the effect of train speed, embankment constituent materials and railway track type on vibration levels. It was found that the shape and magnitude of ground vibration increased rapidly as the train’s speed approached the Rayleigh wave speed of the underlying soil. It was also found that ballast, slab and metal tracks produced similar levels of vibration and that stiffer embankments reduced vibration levels at distances near and far from the track. Two vibration mitigation techniques were also explored through numerical simulation. Firstly, an analysis was undertaken to determine the ability of a new modified ballast material to actively isolate vibration within the track structure. Secondly, wave barrier geometries were investigated to optimise their performance whilst minimising cost. It was found that barrier depth was the most influential parameter, whereas width had little effect. Additionally, geometry optimisation was found to result in a 95% cost saving in comparison to a base case. Using a vast array of results generated using the previously developed finite element model, a new empirical prediction model was also developed, capable of quickly assessing vibration levels across large sections of track. Unlike currently available empirical models, it was able to account for soil properties in its calculation and could predict a variety of international vibration metrics. It was shown to offer increased prediction performance in comparison to an alternative empirical model.

The objective of this study is to identify and examine potential mechanisms of radionuclide transport as vapor at a high-level radioactive waste repository located in unsaturated fractured rock. Transport mechanisms and processes have been investigated near the repository and at larger distances. Transport mechanisms potentially important at larger distances include ordinary diffusion, viscous flow and free convection. Ordinary diffusion includes self and binary diffusion, Knudsen flow and surface diffusion. Pressure flow and slip flow comprise viscous flow. Free convective flow results from a gas density contrast. Transport mechanisms or processes dominant near the repository include ordinary diffusion, viscous flow plus several mechanisms whose driving forces arise from the non-isothermal, radioactive nature of high-level waste. The additional mechanisms include forced diffusion, aerosol transport, thermal diffusion and thermophoresis. Near a repository vapor transport mechanisms and processes can provide a significant means of transport from a failed canister to the geologic medium from which other processes can transport radionuclides to the accessible environment. These issues are believed to be important factors that must be addressed in the assessment of specfic engineering designs and site selection of any proposed HLW repository.

This dissertation examines several questions in Martian surface processes relating to water or ice using a combination of geomorphology and modeling. I first examine sublimation of ice from new small mid-latitude craters with freshly exposed ice imaged by the High Resolution Imaging Science Experiment (HiRISE) camera. I discuss the theory of sublimation by free convection and describe a model that improves on the standard version used in the Mars literature. This model shows some differences from experimental data, but this appears to be because experimental conditions do not accurately capture the sublimation regime appropriate to the Martian surface. I use this sublimation model in concert with a thermal model and calculate sublimation rates at the sites of freshly exposed ice. Calculated sublimated thicknesses of one or more millimeters during the period when HiRISE images show ice imply that this ice is relatively pure, not pore-filling. The ice table thus revealed appears consistent with a model of the Martian subsurface in which relatively clean ice overlies pore-filling ice.Pingos are hills with cores of ice formed by freezing of liquid water under pressure. Possible pingos on Mars have been much discussed because they would have significant implications for Martian hydrological processes. I surveyed HiRISE images across a broad portion of the Martian surface searching for fractured mounds. Such features are candidate pingos, since pingos often develop surface fractures as they grow. A small number of Martian landforms, not previously identified, are morphologically consistent with pingos; however, landforms that appear related to these do show morphological differences from pingos. Other origins are possible, particularly since it is difficult to produce the requisite hydrologic conditions for pingo formation. Previously proposed pingos on Mars lack surface fracturing and are unlikely to be pingos.

A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.

Consumer advice is provided for cooking ground beef to the correct temperature to prevent food-borne illness.

Revised; Originally Published: 2007 / 2 pp.

Samples of ordinary copper, hot-isotactically-pressed (HIP) copper, and simulated borosilicate high-level waste glass were leached at 25°C, 51°C, and 80°C in solutions simulating brine and silicate groundwaters. It was found that the amount of glass leached increased at higher temperatures, and more leaching occurred in brine than in silicate groundwater. This behavior is predicted by Le Chatelier's Principle. Similarly, more copper was dissolved at higher temperatures, and more was dissolved in brine than in silicate groundwaters.

An analysis was performed of a Texas gulf coast hazardous waste injection well disposal system. The system was complicated by the presence of a fault which transected the injection interval. The existence of the fault presented the potential for enhanced vertical migration of the injected solutes via a tortuous path of interconnected, highly permeable sand units. Evaluation of this potential necessitated a fully three dimensional model which incorporated the arrangement of the alternating shales and sands and their associated discontinuities. Computer run time and memory limitations compelled a dissection of the problem into components, as well as the utilization of a specific mixture of conservative and realistic assumptions. The analysis indicated that within 10,000 years, the waste would advance vertically no further than one hundred feet into the overlying stratigraphy, and laterally no further than 24,000 feet from the point of injection.

Morton’s syndrome is a foot condition where the 1st metatarsal does not protrude as far distally as the 2nd metatarsal. Clinicians believe that short 1st metatarsal protrusion affects foot mechanics and leads to painful conditions of the foot. Normal protrusion ratio of the 1st and 2nd metatarsal has not been delineated in scientific literature, and little is known about the mechanics of feet with short 1st metatarsal protrusion beyond anecdotal clinical evidence. In the first part of this two-part study, a novel tool was developed to guide metatarsal measurement and reduce measurement error so values for normal metatarsal protrusion ratios could be established. In the second part, subjects were divided into those with shorter and longer than average 1st metatarsal protrusion ratio and we measured if there were any differences in the foot-floor forces between the two groups. In Part 1, the feet of 65 healthy subjects were measured with a novel measurement tool and it was determined that the average ratio (1st metatarsal/2nd metatarsal) was 0.902, suggesting a 1st metatarsal that does not protrude as far distally as the 2nd metatarsal. For Part 2, participants were divided into two groups: the short 1st metatarsal group had a ratio of more than one standard deviation below the mean (0.866 or lower) while the control group had a metatarsal ratio of more than one standard deviation above the mean (0.938 or higher). We hypothesized that short 1st metatarsal protrusion would cause an imbalance across the forefoot because the 1st metatarsal would not be able to carry the required load on the medial side of the foot; however, the results of the gait study did not show this as only forces in the walking direction near toe-off correlated with metatarsal protrusion ratio. We can only speculate as to the relationship between the metatarsal protrusion ratio and increased shear force in the walking direction, but it is possible that to compensate for the diminished stabilizing capacity of the shorter 1st metatarsal, the foot must push off with more force to propel the body forward. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2013-01-14 14:38:55.255

Landfill leachate, the liquid discharge from Municipal Solid Waste (MSW) landfills, is the combination of the surface runoff and ground water that percolates through the waste and the liquid contained in the waste itself and is considered to be toxic and presents a potential harm to the environment. Raw leachate contains high concentrations of biodegradable and non-biodegradable carbon as well as high concentrations of ammonia nitrogen. Traditionally, landfill leachate has been treated biologically through aerobic processes which reduce the biological carbon to carbon dioxide and biomass (bacterial growth) and ammonia nitrogen to nitrates. Unfortunately this is not sufficient to protect the environment from harm. It is necessary to further treat the leachate anaerobically to transform the nitrates to elemental nitrogen which is removed from the leachate as nitrogen gas. Biodegradable carbon is often the rate limiting substrate as carbon is consumed during the preceding nitrifying phase. Biodegradable carbon can be supplemented through the addition of methanol, at great expense Leachate from the Mariannhill Landfill site is currently treated aerobically in a sequencing batch reactor where nitrification is achieved. The nitrified leachate is then used as a dust suppressant on the current site. It is anticipated that in 2012 the Land fill site would have reached capacity thereby eliminating the need to irrigate and leaving the site with an excess of nitrified leachate that will present an environmental risk. The denitrifying performance of raw commercial garden refuse, pine bark and composted garden refuse as a growth medium and carbon source was investigated through the establishment of batch and column tests. CGR Raw proved the most successful of the three growth media, achieving full denitrification at a loading rate of 1700 mg NO3-N/kg of substrate/day. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.