Design of heavy earthmoving equipment is based primarily on feedback from drivers. Most design studies on ingress and egress focus on the motion itself and rely heavily on experimental data. This process requires physical construction of expensive (in terms of time and money) mockups before any feedback can be obtained. Post-feedback design changes and the analysis of those changes are again expensive processes. Although the design of heavy vehicles requires consideration of human safety and comfort, very little attention has been given to simulating ingress and egress movement for these vehicles. This thesis describes the development of a virtual model to perform ingress and egress motions for heavy equipment and its applications to study the responses of operators with different anthropometries to different cab designs. Different performance measures are suggested and used with predictive dynamics to study human performance since human motion is not governed by a single performance measure. Optimizing multiple performance measures allows the full range of motion for all 55 degrees of freedom to be considered for simulating the task. Once the relevant performance measure was established, case studies were performed on seven different cab designs and digital human models with three different anthropometries. Finally, several different cab design metrics for propensity of injury, comfort, and accessibility were proposed. These design metrics were evaluated for each of the case studies. Finally, each cab design was ranked based on the design metrics to identify the best design for a range of anthropometries. These results help designers make decisions and plan further design changes.

This study investigates the development of a strategy to simulate nuclear graphite oxidation with Computational Fluid Dynamics (CFD) to determine an estimate of graphite lost. The task was achieved by comparing the results of the CFD approach with a number of different experiments. For molecular diffusion, simulated results were compared to analytical solutions. Mass flow rates under conditions of natural convection were sourced from the 2002 NACOK experiment. Experimental data from the KAIST facility were sourced for the basic oxidation of graphite in a controlled environment. Tests included the reactions of carbon with oxygen and with carbon dioxide. Finally, the tests at NACOK from 2004 and 2005 were chosen for comparison for the simulation of oxidation. The 2005 test considered two reacting pebble bed regions at different temperatures. The 2004 test included multiple detailed structural graphite. Comparison of results indicated that the phenomenon of diffusion can be correctly simulated. The general trends of the mass flow rates under conditions of natural convection were obtained. Surface reaction rates were defined with user functions in Fluent. Good comparisons of the simulated and the KAIST experimental results were obtained. For the 2005 NACOK comparison, the pebble bed regions were simulated with a porous medium approach. Results showed that correct trends and areas of oxidation were estimated. The 2004 tests were with a combination of a porous medium and surface reaction approaches. More detailed oxidation experimental data would possibly improve the accuracy of the results. This research has shown that the CFD approach developed in the present study can identify areas of maximum oxidation although the accuracy needs to be improved. Both the porous and detailed surface reaction approaches produced consistent results. The limitations of the approach were discussed. These included transient phenomena which were estimated with steady state simulations, and the effects of change in geometry were not considered. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.

This study investigates the development of a strategy to simulate nuclear graphite oxidation with Computational Fluid Dynamics (CFD) to determine an estimate of graphite lost. The task was achieved by comparing the results of the CFD approach with a number of different experiments. For molecular diffusion, simulated results were compared to analytical solutions. Mass flow rates under conditions of natural convection were sourced from the 2002 NACOK experiment. Experimental data from the KAIST facility were sourced for the basic oxidation of graphite in a controlled environment. Tests included the reactions of carbon with oxygen and with carbon dioxide. Finally, the tests at NACOK from 2004 and 2005 were chosen for comparison for the simulation of oxidation. The 2005 test considered two reacting pebble bed regions at different temperatures. The 2004 test included multiple detailed structural graphite. Comparison of results indicated that the phenomenon of diffusion can be correctly simulated. The general trends of the mass flow rates under conditions of natural convection were obtained. Surface reaction rates were defined with user functions in Fluent. Good comparisons of the simulated and the KAIST experimental results were obtained. For the 2005 NACOK comparison, the pebble bed regions were simulated with a porous medium approach. Results showed that correct trends and areas of oxidation were estimated. The 2004 tests were with a combination of a porous medium and surface reaction approaches. More detailed oxidation experimental data would possibly improve the accuracy of the results. This research has shown that the CFD approach developed in the present study can identify areas of maximum oxidation although the accuracy needs to be improved. Both the porous and detailed surface reaction approaches produced consistent results. The limitations of the approach were discussed. These included transient phenomena which were estimated with steady state simulations, and the effects of change in geometry were not considered. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.

Submitted by Daniel marques (danielmarquescontato@gmail.com) on 2016-08-18T12:08:15Z No. of bitstreams: 1 _Dissertacao_DanielMarques.pdf: 10941912 bytes, checksum: 327d8d4fb97533c7c0209603a12ad878 (MD5) / Approved for entry into archive by Patricia Barroso (pbarroso@ufba.br) on 2016-08-18T20:18:49Z (GMT) No. of bitstreams: 1 _Dissertacao_DanielMarques.pdf: 10941912 bytes, checksum: 327d8d4fb97533c7c0209603a12ad878 (MD5) / Made available in DSpace on 2016-08-18T20:18:49Z (GMT). No. of bitstreams: 1 _Dissertacao_DanielMarques.pdf: 10941912 bytes, checksum: 327d8d4fb97533c7c0209603a12ad878 (MD5) / A presente pesquisa, a partir da análise do jogo móvel locativo Ingress enquanto objeto de estudo, toma como objetivo principal o mapeamento das novas perspectivas de manifestação de narratividade emergente a partir de produtos culturais mediados por software e novas mídias. Para tanto, a pesquisa parte para a investigação, através da revisão de literatura, do estado da arte da produção de narratividade na contemporaneidade, compreendendo esse processo enquanto uma atividade cognitiva – e criativa – inerente a condição humana. Nesse sentido, a pesquisa segue na compreensão de como se manifesta a narratividade emergente também nos games, enquanto ambientes de simulação, identificando as diferentes perspectivas que compõe um jogo enquanto ambiente procedimental capaz de veicular conteúdo narrativo além da sua codificação semiótica inicial. A pesquisa avança, a partir da apropriação inicial das teorias do campo da narrativa, para uma compreensão do cenário infocomunicacional contemporâneo, marcado pela presença dos fenômenos de softwarização e dataficação da cultura. Dessa forma, pode-se compreender de que forma a produção de produtos culturais assentados em software e coleta de dados pode apresentar novos caminhos e desafios para a produção narrativa, ainda através da revisão de literatura e levantamento bibliográfico. Tendo como base o aporte teórico levantado, o presente estudo propõe uma análise empírica e de caráter experimental do jogo móvel locativo Ingress, tendo como parâmetro uma matriz de análise desenvolvida especificamente para a questão. Constrói-se, portanto, um mapeamento das características principais do game enquanto software, ambiente de simulação e produto narrativo, buscando assim expor as relações e contaminações entre as estas diferentes camadas. O processo de análise culmina, portanto, na exposição de novas perspectivas para a emergência de narratividade, levando em consideração a abertura do sistema de simulação para o input de dados e performances diversas dos jogadores. / This research, based on the analysis of the mobile locative game Ingress, have as main objective mapping new prospects for emerging narrative behavior from cultural products mediated by software and new media. The research begins with a literature review, aiming to identify the state of the art of narrative production in contemporary times, understanding this process as a cognitive and creative activity inherent to the human condition. In this sense, the research follows to understand how emergent narrative manifests itself also in simulation environments, identifying the different perspectives that allows games, while procedural environments, to convey narrative content beyond its initial semiotic encoding. The research progresses, from the initial appropriation of the narrative field theories for a deeper comprehension of the contemporary informational scenario, marked by the presence of softwarization and datafication culture. Thus, one can understand how the production of cultural products seated in software and data collection can present new challenges for the narrative production. Based on the theoretical approach, this study offers an empirical and experimental analysis of the mobile locative game Ingress, based on an analysis matrix developed specifically for the issue. It helps, therefore, in mapping some of the major features of the game as software simulation environment and narrative product, thus seeking to explain the relations between the contamination of these different layers. The review process culminates in the exhibition of new prospects for the emergence of narrative, taking into account the opening of simulation system for the input data and various performances of the players.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Hitesh Bindra / Helium-cooled, graphite moderated reactors have been considered for a future fleet of high temperature and high efficiency nuclear power plants. Nuclear-grade graphite is used in these reactors for structural strength, neutron moderation, heat transfer and, within a helium environment, has demonstrated stability at temperatures well above HTGR operating conditions. However, in the case of an air ingress accident, the oxygen introduced into the core can affect the integrity of the fuel graphite matrix. In this work a combination of computational models and mixed effects experiments were used to better understand the air ingress process and its potential effects on the heat removal capabilities of an HTGR design following an air-ingress accident. Contributions were made in the understanding of the air-ingress phenomenon, its potential effects on graphite, and in experimental and computational techniques. The first section of this thesis focuses on experimental and computational studies that were undertaken to further the understanding of the Onset of Natural Convection (ONC) phenomenon expected to occur inside of an HTGR following an air ingress accident. The effects of two newly identified factors on ONC – i.e., the existence of the large volume of stagnate helium in a reactor's upper plenum, and the possibility of an upper head leak – were investigated. Mixed-effects experimental studies were performed to determine the changes induced in nuclear grade graphite exposed to high-temperature, oxidizing flow of varying flow rates. Under all scenarios, the thermal diffusivity of the graphite test samples was shown to increase. Thermal conductivity changes due to oxidation were found to be minor in the tested graphite samples – especially compared to the large drop in thermal conductivity the graphite is expected to experience due to irradiation. Oxidation was also found to increase the graphite's surface roughness and create a thin outer layer of decreased density. The effects of thermal contacts on the passive cooling ability of an HTGR were experimentally investigated. Conduction cool down experiments were performed on assemblies consisting of a number of rods packed into a cylindrical tube. Experimental conditions were then modeled using several different methodologies, including a novel graph laplacian approach, and their results compared to the experimentally obtained temperature data. Although the graph laplacian technique shows great promise, the 2–D Finite Element Model (FEM) provided the best results. Finally, a case study was constructed in which a section of a pebble bed reactor consisting of a number of randomly packed, spherical fuel particles was modeled using the validated FEM technique. Using a discrete elements model, a stable, randomly packed geometry was created to represent the pebble bed. A conduction cool down scenario was modeled and the results from the FEM model were compared to best possible results obtainable from a more traditional, homogeneous 1–D approximation. When the graphite in the bed was modeled as both oxided and irradiated, the homogeneous method mispredicted the maximum temperature given by the 3–D, FEM model by more than 100°C.

This thesis introduces game Geocaching and an alternative game Ingress. Geocaching is currently very popular activity for tourists which is causing growth of environmental hazard due to increasing number of players around the world The theoretical part includes description of the game and the risks associated with it. The thesis presents also an alternative game Ingress, which is environmnetal friendly thanks to its virtual character. This thesis brings new routes in close surroundings of Radešín village for Geocaching and Ingress in order to increase attractivity of the place. A questionaire survey which is evaluated in the final section was designed to determine the awareness of Geocaching and Ingress and their impact on the environment.

Gas turbines operate with medium of very high temperatures, which requires using advanced materials for vanes and blades and sophisticated methods of their cooling. Other parts of the turbine have to be protected from contact with hot gases. Discs that hold vanes and blades are especially exposed to this danger. In order to avoid it certain improvements have to be applied: providing sealing air and adjusting geometry of the hub to make the ingress to the cavity (space between discs)more difficult. This thesis concerns CFD investigation of the influence of the amount of sealing air on sealing efficiency and on the flow in the main annulus. The first part concerned literature study. Phenomena of ingress and interaction between main flow and sealing air were described. Different methods of estimating efficiency were shown. The second part focused only on the main path of the gas, modeling secondary air as constant and uniform outflow through the opening. The aim was to investigate how the power and reaction rate depend on the secondary air. The results were also exported to be used as boundary condition in the second part of the thesis. The last part concerned only the cavity – conditions at the main annulus were taken from the main annulus solution. Pressure in specified locations was measured and used to calculate sealing efficiency. Results were compared with the theoretical equations from the literature study. A structure of the flow inside the cavity was analyzed for several different amounts of the sealing flow. A method of unsteady flow analysis was developed and described. It was successfully implemented which proves that the method is promising. However, some improvements are necessary to obtain stable solution and research in this field should be continued. / Turbopower

Threshold leak sizes and leak rates were calculated for a number of liquid food products exhibiting a wide range of surface tension and viscosity values. From this data, one can see that mathematically, under typical pressure differentials generated in food packages (less than or equal to ±34.5 kPa), a leak will never start through a 2 μm defect. The calculated leak rates were compared to calculated evaporation rates. The evaporation rate exceeds the leak rate at lower sized microholes (2, and 5 μm diameter) under typical pressure differentials found in food packages. If the liquid, typically aqueous in food products, is evaporating off faster than the leak itself, then there will be solids left behind that could effectively plug the leak. The critical leak size is the size micro-defect that allows microbial penetration into the package. The critical leak size of air-filled defects was found to be 7 μm at all pressures tested. This size is considerably important to food packagers because this is when sterility of the package is lost. Previous leak studies have shown that the critical leak size for liquid-filled defects coincide with the threshold leak size and pressure. If this is in fact true, then air-filled defects should exhibit a larger critical leak size than the liquid-filled defects. In this study, air-filled defects were examined. A bioaerosol exposure chamber was used to test micro-defects, nickel microtubes of known diameters 2, 5, 7, 10, 20, and 50 μm hydraulic diameters, against pressure differentials of 0, -6.9, -13.8, and -34.5 kPa. / Master of Science

Dirt ingress in hydraulic cylinders is one of the sources that leads to pollution of hydraulic systems. There are already several test rigs to investigate external contamination mechanisms. However, until now only the behavior of the whole sealing system was analyzed. A new testing method to understand the dirt particle transport between a reciprocating motioned rod and a wiper is presented. The new approach aims to avoid known issues such as limited reproducibility and long duration. The paper describes the test rig design and operating principle. First measurement results are shown.

This thesis investigates, both theoretically and experimentally, the phenomenon of ingress through gas turbine rim seals. The work presented focuses on modelling and measuring the required sealing flow levels to purge the wheelspace against combined ingress and the effect of externally-induced ingress on the surface temperature and heat transfer to the rotor. Combined ingress is driven by a pressure difference between the mainstream annulus and wheelspace cavity resulting from the combination of the asymmetric external pressure profile in the annulus and the rotation of fluid in the rotor-stator wheelspace cavity. Ingress can be prevented by pressurising the wheelspace through the supply of sealant flow. The Owen (2011b) combined ingress orifice model was solved to predict the required levels of sealant flow to prevent ingress into the wheelspace. The model was validated using prepublished data and data collected experimentally over the course of this research. Gas concentration measurements were made on the stator of the Bath single-stage gas turbine test rig to determine the variation of sealing effectiveness with sealant flow rate for an axial clearance seal geometry at design and off-design operational conditions. The measured variation of the required sealant flow rate with the ratio of the external and rotational Reynolds numbers, ReW / Reϕ, was consistent with the findings of other workers: at low values of ReW / Reϕ, ingress levels were influenced by the combined effects of the disc rotation and the annulus pressure profile and were therefore considered to fall into the combined ingress region; the influence of rotation diminished as ReW / Reϕ increased and the ingress levels were dominated by the annulus pressure field (externally-induced ingress). The orifice model was in good agreement with the experimental measurements and the prepublished experimental data. Thermochromic liquid crystal (TLC) was used to determine effect of ingress on the heat transfer coefficient, h, and adiabatic wall temperature, Tad, on the rotor of the Bath gas turbine rig. Concurrent gas concentration measurements were made on the stator to compare the effects of ingress on the two discs. Data was collected at the design condition, where ReW / Reϕ = 0.538 and at an overspeed off-design condition, where ReW / Reϕ = 0.326. The comparison between a newly defined adiabatic effectiveness, εad, on the rotor and the concentration effectiveness, εc, on the stator, showed that the rotor was protected against the effects of ingress relative to the stator. The sealing air, which is drawn into the rotor boundary layer from the source region, thermally buffers the rotor against the ingested fluid in the core. A thermal buffer ratio, η, was defined as the ratio of the minimum sealant flow required to purge the stator against ingress to the minimum sealant flow required to purge the rotor against ingress. The thermal buffer is dependent upon the flow structure in the wheelspace, which itself is governed the turbulent flow parameter, λT. A hypothesis relating η to λT was developed and shown to be in good agreement with the experimental data. The local Nusselt numbers, Nur, on the rotor were shown to be fairly constant with radius and increased as λT was increased. The latter finding can be explained by the flow structure in the wheelspace: as λT is raised, the swirl in the fluid core reduces, which results in an increase in the moment coefficient and Nur on the rotor. Difficulties in measuring Tad during the experiments suggested a new technique from which to solve for h and Tad using TLC surface temperature measurements. The solution Fourier’s equation for a step-change in the temperature of a fluid flowing over a solid of semi-infinite thickness (the ‘semi-infinite solution’) is limited to relatively low Fourier numbers if Tad is to be calculated accurately. A two-layer composite substrate made from, for example, polycarbonate and Rohacell, could be used to achieve accurate estimates of h and Tad over a larger range of Biot numbers than for a single material substrate. TLC could be used to measure the surface temperature history of the composite substrate during an experiment; this would allow h and Tad to be solved from the numerical solution of Fourier’s equation or from a combination of the semi-infinite and steady-state solutions. The work presented in this thesis has uncovered some interesting findings in areas where research was limited. The measurements of the minimum sealant flow required to purge the wheelspace at off-design operation for a rotor-stator system with blades and vanes and the measurements of the adiabatic effectiveness on a rotating disc affected by ingress are unique and provide a platform for further experimental studies and validation of CFD models.