Thesis (Ph. D.)--Rhodes University, 2006. / Title from PDF t.p. (viewed on Apr. 12, 2007). Includes bibliographical references (p. 184-207).

Shear blades are mostly made of cold-work tool steels and manufactured by rolling process. Rolling process is performed not only for forming the tool but also for improving the mechanical properties. In this study, an alternative method, involving sand casting, hot forging and heat treatment processes to manufacture the shear blades, has been proposed. In the proposed method, plastic deformation will be carried out by means of forging instead of rolling. The material has been selected as X48CrMoV8-1. For both of casting and forging processes, simulations have been conducted by using Computer Aided Engineering Software. According to the results of casting process simulation, the billets have been poured. These billets have been soft annealed first and then taken as the initial raw material for the forging process. After the forging process, quenching and tempering processes have been applied. The specimens have been taken as cast, as forged and as tempered and the microstructural analysis and mechanical tests have been performed on these. The same tests and analysis have been repeated for a commercially available shear blade sample which is manufactured by rolling. All these investigations have shown that the properties of the forged shear blade are very similar to the rolled shear blade. Therefore, the new proposed method has been verified to be used as an alternative manufacturing method for the cold-work tool steel shear blades.

Due to the environmental issues related with fuel consumption and additionally passenger safety, aluminum space frame chassis is promising a big opportunity to design a lightweight structure with a high stiffness. Despite the lower stiffness and strength of aluminum in comparison to the conventional steel chassis, it can be compensated with changing thickness and design of structure by space frame geometry In this study, instead of using steel for automobile chassis, main goal is producing a space frame structure with using aluminum in an extrusion and sand casting processes and improve the stiffness. Chassis is designed according to calculations for moment of inertia, torsional and bending stiffness and in sufficient structural stiffness which can compete with steel chassis. Static finite element analysis was carried out to understand the chassis bending, torsional stiffness and fatigue behaviors. For frontal collisions, dynamic finite element analysis was also done to determine increases in the energy absorbance, specific energy absorbance and peak force for passenger safety. Aluminum profiles were produced by hot extrusion and joined with sand casting parts by TIG welding to manufacture a space frame structure. For main chassis profile, 6063 series of aluminum alloy was selected due to availability for extrusion process, weldability and having sufficient tensile strength and percent elongation and treatment response. Three point bending test was carried out to determine flexural strength. Moment of inertia calculations were done. Some parts such as side frame and shock absorber tower were produced by sand casting method. A similar composition to Silafont &ndash / 36 aluminum alloy was selected because of its high fluidity and good mechanical properties / despite it is a die cast alloy. Tensile, hardness and Charpy impact test were conducted to determine the mechanical characteristics of Silafont - 36 sand cast alloy. In addition to microstructure features and thermal analysis were also carried out to achieve sufficient alloy properties. Heat affected z one was investigated by hardness and tensile test to determine the mechanical properties change after welding process. In this space frame development study, A, B and C pillar parts were produced by Al &ndash / Si sand casting and T6 heat treatment then welded together by TIG welding and finally assembled on the bottom chassis frame produced by using 6063 extrudes welded by 4000 series electrodes. The space frame chassis was studied by also computer simulation to test and see critical points which must be modified during manufacturing. Besides the experimental and theoretical studies, space frame was also produced at the same time. According to the experimental results, the feasibility of the production of lightweight and solid chassis structure was achieved.

Foredunes are formed and developed in association with vegetation. A bare sand area has been viewed as a measure of dune mobility or activity and researched in association with climate controls: particularly wind power, annual mean precipitation, and temperature, expressed in annual mean potential evapotranspiration. There has been no research that utilized the patterns of bare sand areas to classify foredune areas in coastal dune systems and investigated climate controls related to sand patch patterns, or “foredune textures” such as size, number, and distribution of sand patches Four foredune types were classified based on four landscape metrics (PLAND: percentage of bare sand area, PLADJ: proportion of like-adjacencies, NLSI: normalized landscape shape index, and ENN_RA: range of Euclidean nearest neighbor), by applying the concepts and methodologies of landscape ecology. Four climate variables (annual mean precipitation, annual mean potential evapotranspiration, Lancaster’s mobility index, and the standard deviation of annual mean precipitation) were found to affect the foredune types and help in distinguishing one foredune type from another. The amount of bare sand area on coastal foredune areas can be explained by annual mean precipitation (R^2 is 0.52 at the 99 % confidence level), standard deviation of precipitation (R^2 is 0.51 at the 99 % confidence level), and Lancaster’s mobility index (R^2 is 0.37 at the 99 % confidence level) but wind variables such as drift potential do not explain much (R^2 is 0.04 at maximum). This suggests that dune activity or stabilization in coastal dune systems is mainly controlled by vegetation cover, which is in turn affected by precipitation. Foredune textures can be a useful tool to predict foredune types in association with future climate change, and the optimal averaging period of precipitation for each bare sand area was seven years.

Foundries are most widely facilities all around the world, producing high amounts of castings. In this study, environmental impact of metal foundries was investigated toward a life cycle assessment (LCA) goal. Studies were conducted in two foundry plants in order to collect the inventory data. The difference between the plants regarding their processes was the application of secondary sand reclamation (SSR) in Plant 2. Application of SSR is indicated as a

Naphthenic acids (NAs) are carboxylated alkanes and cycloalkanes concentrated in wastewater during oil sands processing. The general chemical formula is C{n}H{n+Z}O{2}, where n represents the number of carbon atoms and Z specifies a homologous family with 0-6 rings (Z=0 to Z=-12). The wastewater is acutely toxic to surface water organisms and is stored in tailings ponds with over 230 million m³ of fines tailings and free water. The purpose of this thesis was to provide a preliminary evaluation of the potential attenuation of NAs during groundwater flow from the ponds. Laboratory studies were conducted to evaluate possible attenuation mechanisms. Aerobes from aquifer material degraded 60% of the NAs over 20 weeks in laboratory microcosms. The greatest decrease occurred in the low molecular weight bicyclic homologues with 12 to 16 carbons. The microbial activity confirms that aerobic naphthenate-degrading bacteria occur naturally in the glacial aquifer near Suncor's Pond 2/3. These results support the hypothesis that limited aerobic biodegradation of the smaller components of NAs could occur relatively rapidly under field conditions. There was no measurable decrease in NA concentration over six months in anaerobic microcosms, although microbial activity did lead to sulfate-reducing and methanogenic conditions. The theoretical retardation in glacio-fluvial sands was calculated using soil-water partitioning coefficients (K{d}) determined by batch equilibration experiments using a mixture of naturally occurring naphthenic acids as well as the nine surrogates. The retardation (porosity of 0. 3, bulk density of 1. 5 g/mL) ranged from 1. 2 to 2. 6. However, no measurable sorption was seen at the field sites. Detailed characterization allows us to examine how the proportions of homologue, or groups of molecules with the same molecular weight and number of cycloalkane rings, vary. Aerobic biodegradation favoured removal of low molecular weight NAs. A 15% mass loss attributed to sorption caused no changes in the 3D signature. Thus, changes in NA "signature" in groundwater systems were then attributed to aerobic biodegradation. Three plumes were examined for evidence of attenuation of NAs via biodegradation. First, the individual samples were classified as background, possibly process-affected or process-affected using a combination of Piper diagrams, the stable isotopes oxygen-18 and deuterium, dissolved chloride and sodium, as well as the total naphthenic acids concentration. Second, in order to estimate attenuation due to dispersive dilution, a linear correlation line was drawn between various conservative tracers and the naphthenic acids concentration. This allowed the identification of certain samples as possibly having a lower concentration of NAs than could be expected from simple dispersive dilution. Third, the 3D signature of certain samples were examined for the presence of the aerobic biodegradation 3D signature. One site showed good evidence for aerobic biodegradation of naphthenic acids. A second site showed some evidence for biodegradation under methanogenic conditions but the evidence was not definitive. The evidence at the third site was contradictory and no conclusions could be drawn from it. This research suggests some attenuation of NAs by biodegradation may be possible during groundwater flow.

This research aimed to address the knowledge gaps in the literature regarding the removal of waterborne pathogens (viruses and protozoa) by modified multistage slow sand filtration. In the current study, two pilot-scale multistage slow sand filtration systems were operated continuously for over two years. The pilot systems treated agricultural- and urban-impacted raw river water of variable quality with turbidity peaks over 300 NTU and seasonal cold temperatures <2°C. The first system (Pilot 1) consisted of two independent trains that included pre-ozonation, shallow-bed upflow gravel roughing filtration, and shallow-bed slow sand filtration. Pilot 1 was a pilot-scale version of an innovative, commercially available full-scale system. The second system (Pilot 2) included a full-depth upflow gravel roughing filter, a full-depth slow sand filter, and a second shallow-depth slow sand filter in series. The SSFs of both pilots were operated at high hydraulic loading rates (typically 0.4 m/h) at the upper limit of the literature recommended range (0.05 to 0.4 m/h). Both pilot systems provided excellent turbidity removal despite the high filtration rates. Effluent turbidity of all multistage SSF pilot systems were within the regulated effluent limits in Ontario for full-scale SSFs (below 1 NTU at least 95% of the time and never exceeded 3 NTU), despite raw water turbidity peaks over 100 NTU. The roughing filters contributed to approximately 60-80% of the full-train turbidity removal, compared to and 20-40% for the slow sand filters. On average, the second slow sand filter in pilot 2 provided almost no additional turbidity removal. The slow sand filter run lengths were short because of frequent high raw water turbidity, with about 50-80% of the runs in the range of 1-3 weeks. To prevent excessive SSF clogging and maintenance, filtration rates should be decreased during periods of high turbidity. Seven Cryptosporidium and Giardia challenge tests were conducted on the slow sand filters of both pilot systems at varying filtration rates (0.4 or 0.8 m/h), temperatures (2 to 25°C), and biological maturities (4 to 20 months). Removal of oocysts and cysts were good regardless of sand depth, hydraulic loading rate, and water temperature in the ranges tested. Average removals in the SSFs ranged from 2.6 to >4.4 logs for Cryptosporidium oocysts and ranged from >3.8 to >4.5 logs for Giardia cysts. This was consistent with findings in the literature, where oocyst and cyst removals of >4 logs have been reported. Cryptosporidium oocyst removals improved with increased biological maturity of the slow sand filters. At a water temperature of 2°C, average removal of oocysts and cysts were 3.9 and >4.5 logs, respectively, in a biologically mature SSF. Doubling the filtration rate from 0.4 to 0.8 m/h led to a marginal decrease in oocyst removals. Sand depths in the range tested (37-100 cm) had no major impact on oocyst and cyst removals, likely because they are removed primarily in the upper section of slow sand filter beds by straining. In general, good oocyst and cyst removals can be achieved using shallower slow sand filter bed depths and higher filtration rates than recommended in the literature. There are very few studies in the literature that quantify virus removal by slow sand filtration, especially at high filtration rates and shallow bed depths. There are no studies that report virus removal by slow sand filtration below 10°C. As such, 16 MS2 bacteriophage challenge tests were conducted at varying water temperatures (<2 to >20°C) and filtration rates (0.1 vs. 0.4 m/h) between February and June 2006 on biologically mature slow sand filters with varying bed depths (40 vs. 90 cm). Biologically mature roughing filters were also seeded with MS2. Average MS2 removals ranged from 0.2 to 2.2 logs in the SSFs and 0.1 to 0.2 logs in the RFs under all conditions tested. Virus removal by slow sand filtration was strongly dependant on hydraulic loading rate, sand depth, and water temperature. Virus removal was greater at a sand depth of 90 cm vs. 40 cm, at an HLR of 0.1 m/h vs. 0.4 m/h, and at warm (20-24°C) vs. cold (<2-10°C) water temperatures when sufficient warm water acclimation time was provided. Increased sand depth likely increased MS2 removal because of greater detention time for predation and greater contact opportunities for attachment to sand grains and biofilms. A lower HLR would also increase MS2 removal by increasing detention time, in addition to decreasing shear and promoting attachment to filter media and biofilms. Greater MS2 removal at warmer water temperatures was attributed to improved biological activity in the filters. Schmutzdecke scraping was found to have only a minor and short-term effect on MS2 removals. Virus removal can be optimized by providing deep SSF beds and operating at low filtration rates. Virus removal may be impaired in cold water, which could affect the viability of using SSF/MSF at northern climates if communities do not use disinfection or oxidation. As a stand-alone process, slow sand filtration (with or without roughing filtration) may not provide complete virus removal and should be combined with other treatment processes such as disinfection and oxidation to protect human health.

The reason to return is a phenomenon which tells us that many people want to travel back to a destination they visited before. Even if there are changes in the society with the New tourist who seeks for the authentic, this essay is proving that there still is a dominance of repeat tourism and search for belonging and safety. That implication shows evidence that there still are remaining from old tourism about security with the destination and so on. Further, investigation tells us about the returning tourists, their driving forces and push-factors that create a will for tourists to return. Is it a question of how loyal tourists are to the destination, attitudes and/or tradition when planning the trip? We have made a survey that covers why tourists travel and what impacts are created during their decisions. Also included are the questions about the will of return and the reasons why. Having children proved to be a crucial part of the decision making process, where parents chose destinations out of the children-oriented places. Returning to a destination, on the other hand, is a product of safety-seeking together with a positive experience and beautiful surroundings, all weaved up to raison d'être - just to be.

In the study, the thickness of wave moved-sediment layers was measured under regular wave conditions as well as the initial slope of sea bed with grain size of medium diameter 0.237mm and 0.128mm. The initial bottom slope ( tan£\) is 1/45, and nineteen wave conditions were studied. For each case, we analyzed the results after about 28800 waves were made. Sands are similar density and grain size but different colors. After wave action, the clear boundary between the two layers (two different colors) of sands will be mixed into gray color by wave-induced vortex.According to unmoved-layer(white) and gray-layer to get the total wave-moved sediment quantity. Finally, we get the relationship between the wave-moved sediment quantity per wave( q) and two parameters( £`b and £Kb ) which were established by Liao (2005, doctorate draft). The grain size does not affect £`b , and we get the q= 6.486*10^-5*£`b . The relationships between and ¡G 0.110mm gets q=5.103*10^-6£Kb , 0.128mm gets q=1.139*10^-5*£Kb, and 0.237mm gets q=1.933*10^-5*£Kb .

Understanding how swirl flows can be applied to processes in the oil and gas industry and how problems might hinder them, are the focus of this thesis. Three application areas were identified: wet gas metering, liquid loading in gas wells and erosion at pipe bends due to sand transport. For all three areas, Computational Fluid Dynamics (CFD) simulations were performed. Where available, experimental data were used to validate the CFD results. As a part of this project, a new test loop was conceived for the investigation of sand erosion in pipes. The results obtained from CFD simulations of two-phase (air-water) flow through a pipe with a swirl-inducing device show that generating swirl flow leads to separation of the phases and creates distinct flow patterns within the pipe. This effect can be used in each of the three application areas of interest. For the wet gas metering application, a chart was generated, which suggests the location of maximum liquid deposition downstream of the swirling device used in the ANUMET meter. This will allow taking pressure and phase fraction measurements (from which the liquid flow rate can be determined) where they are most representative of the flow pattern assumed for the ANUMET calculation algorithms. For the liquid loading application, which was taken as an upscaling of the dimensions investigated for the wet gas metering application, the main focus was on the liquid hold-up. This parameter is defined as the ratio of the flowing area occupied by liquid to the total area. Results obtained with CFD simulations showed that as the water rate increases, the liquid hold-up increases, implying a more effective liquid removal. Thus, it was concluded that the introduction of a swirler can help unload liquid from a gas well, although no investigation was carried out on the persistance of the swirl motion downstream of the device. For the third and final application, the erosion at pipe bends due to sand transport, the main focus was to check the erosion rate on the pipe wall with and without the introduction of a swirler. The erosion rate was predicted by CFD simulations. The flow that was investigated consisted of a liquid phase with solid particles suspended in it. The CFD results showed a significant reduction in erosion rate at the pipe walls when the swirler was introduced, which could translate into an extended working life for the pipe. An extensive literature review performed on this topic, complemented by the CFD simulations, showed the need for a dedicated multiphase test loop for the investigation of sand erosion in horizontal pipes and at bends. The design of a facility of this type is included in this thesis. The results obtained with this work are very encouraging and provide a broad perspective of applications of swirl flows and CFD for the oil and gas industry.