Reducers are commonly used in many types of machines to reduce the speed and increase the torque of motors. For general industrial applications, the reduction ratio of a reducer is usually limited in consideration to its size. To provide high reduction ratios, harmonic drives (speed reducers) can be made very compact and lightweight and thus have been popular with robot manufactures and in other applications where weight is critical. In this study, an innovative design for reducers composed of planar cams and roller followers with high reduction ratios is proposed. It uses the relative motion between rollers and their cams to generate a high reduction ratio. In this thesis, the synthesis procedure of the reducer and the analysis results of the kinematic and dynamic characteristics based on the design parameters are also described. Furthermore, the experiments for testing and verifying the characteristics of the reducer are presented. Finally, a set of design parameters which meets the demand of an application is found by optimization methods.

Stone column technique is mostly used to reinforce soft cohesive soils. Settlements are decreased under foundations and bearing capacity is increased. This study initially focuses on a comprehensive review of literature about stone column reinforced soils. Afterwards, numerical modeling of stone column reinforced soft clays is done. Three different cases are chosen on different foundation soils mainly soft clays. Parametric studies are done to determine influence of parameters on settlement reduction ratio under three different foundation conditions. Analyses are converted to two dimensional conditions and this conversion is also compared within the scope of this study. Settlement reduction ratio response to variation in parameters revealed similar results under three different foundation conditions.

ABSTRACT A LABORATORY MODEL STUDY ON SETTLEMENT REDUCTION Effect OF STONE COLUMNS IN SOFT CLAY S&uuml / nnetcioglu, Mehmet Emrah M.Sc., Department of Civil Engineering Supervisor: Prof. Dr. Mehmet Ufuk Ergun August 2012, 177 pages An experimental study was conducted in order to examine settlement reduction ratios of footing supported by both floating and end bearing type of stone columns. For the floating types, tests were done with varying column lengths of one and two widths of footing (L=B,2B). Tests were conducted in 200 mm* 200 mm* 200 mm cubic loading tanks. The reinforcement effect was achieved by the installation of four stone columns with 20 mm diameter under 70 mm* 70mm model footing. Parameters such as area replacement ratio (a_s), loading plate dimensions, consolidation and vertical pressures applied, and the relative density (D_R) of the granular column were kept constant, the column length (L) was set as the only variable in the experimental tests conducted. In the tests, footing settlements together with subsurface settlements at depths equal to footing width (B) and two times the footing width (2B) were measured by specially designed telltales. The settlement reduction ratios both at surface and subsurface were evaluated in order to determine the effect of column length on settlement improvement. It has been found out that as the column length increases the settlement reduction ratios decrease for all depth intervals. However, there exists a threshold column length (L=2B), beyond which the composite ground demonstrates little settlement improvement.

This study discusses the results of numerical modeling aspect of aggregate pier foundations (aggregate piers) in soft, compressible soils. FLAC 2D (Fast Lagrangian Analysis of Continua), a finite difference code is utilized in the analyses. Use of axisymmetry enabled to visualize a three dimensional model throughout this research. The primary objective of this research is to make comparisons for stress concentration ratio &lsquo / n&rsquo / , and settlement reduction ratio b for given variables consisting of length, diameter, elastic modulus of the aggregate piers, and foundation pressures. Analyses have been carried out with 1, 1.5, 2, and 3 m long piers with diameters of 60 cm, and 80 cm, placed under a circular footing in 1.30 m diameter. Two values for elastic modulus of the piers have been used to reflect the effect of pier stiffness on settlement behavior. Analysis and design methodology have been carried out in three stages. The first stage consists of modeling the matrix soil with an elastic constitutive model and exerting foundation pressures to first check the accuracy of the mesh by comparing the effective vertical stress and settlement values by analytical methods. Once satisfactory results are achieved, modeling of a rigid foundation is carried out. Consequently, aggregate piers are modeled and loaded. For foundation pressures, a range of values consisting of 25, 50, 75, and 100 kPa have been chosen to see the behavior of piers under variable foundation pressures. There are solid outcomes of this study. It concludes by stating that the settlement behavior of piers having L/d ratios greater than 3.75, are alike. Thus, there is almost no additional settlement improvement achieved with piers longer than 3 m with 60 cm pier diameter.

Justificativa: Doses inadequadas de diálise estão associadas a maior morbidade e mortalidade em pacientes com uremia terminal em tratamento hemodialítico. Atualmente os métodos mais utilizados para medir a adequação da hemodiálise baseiam-se no cálculo da depuração fracional de uréia (Kt/V) e da taxa de redução da uréia (URR). Nesse estudo avaliou-se a reprodutibilidade do Kt/V e da URR e analisou-se o número aceitável de medidas mensais destes parâmetros para determinar de forma fidedigna a adequação da hemodiálise. Métodos: Avaliamos 43 pacientes clinicamente estáveis, em cinco sessões de hemodiálise (sessões 1 a 5), durante três semanas. Três diálises consecutivas na primeira semana (sessões 1, 2, 3) e duas sessões de meio de semana, nas duas semanas subseqüentes (sessões 4 e 5). Resultados: Não houve diferença entre a média dos Kt/Vs obtidos em diálises seqüenciais (1, 2 e 3) comparada a média dos Kt/Vs obtidos em diálises no meio da semana (2, 4 e 5). O mesmo aconteceu com a URR e com os coeficientes de variação do Kt/V e da URR. Também não encontramos diferença entre uma medida mensal (Kt/V 2) e três medidas mensais (média dos Kt/Vs 2, 4 e 5). O mesmo ocorreu com a URR. A diferença entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 foi de – 0,02 unidades e entre a URR 2 em relação a média das URRs 2, 4 e 5 foi de – 0,5%. Além disso, se fizermos apenas uma medida mensal (Kt/V 2) 80% dos pacientes estarão a uma distância de no máximo 0,16 unidades abaixo da média dos Kt/Vs 2, 4 e 5 e no máximo 0,12 unidades acima. Em relação a URR 80% dos pacientes estarão a uma distância de no máximo 4,37% abaixo da média das URRs 2, 4 e 5 e no máximo 3,37% acima. O grau de concordância entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 é bom para pontos de corte do Kt/V igual ou superior a 1,3. No caso da URR a concordância é boa para pontos de corte acima de 65%. Conclusão: Concluímos que nesta população de pacientes clinicamente estáveis os parâmetros de adequação da hemodiálise mostraram-se reprodutíveis não havendo necessidade de aumentar o número de medidas mensais da quantidade de diálise ofertada. / Background: Inadequate doses of dialysis are associated with higher morbidity and mortality rates for end-stage renal disease (ESRD) patients undergoing hemodialysis treatment. Most methods aimed at measuring dialysis adequacy use the calculation of fractional clearance of urea (Kt/V) and urea reduction ratio (URR). This study evaluates the reproducibility of Kt/V and URR and analyzes the acceptable number of monthly measurements of these parameters to determine hemodialysis adequacy. Methods: We evaluated 43 clinically stable patients in five hemodialysis sessions (1 to 5) along three weeks. Three consecutive sessions were carried out in the first week (1, 2, 3), while the two other studied sessions were carried out in the middle of the week at weekly intervals (4, 5). Results: There was no difference between mean Kt/V in sessions 1, 2, and 3 and in sessions 2, 4, and 5. The same was observed for URR and the coefficients of variation for Kt/V and URR. Either differences were found between one monthly measurement (2) or three monthly measurements (mean of 2, 4, and 5) for Kt/V and URR. The difference between Kt/V 2 and the arithmetic mean of Kt/Vs 2, 4, and 5 was – 0.02 units, and between URR 2 and the mean of URRs 2, 4, and 5 was – 0.5%. When only one monthly measurement (Kt/V 2) was considered, 80% of the patients presented ≤0.16 unit below or ≤0.12 above the mean of Kt/Vs 2, 4, and 5. For URR, 80% of patients presented ≤4.73% below or ≤3.37% above the arithmetic mean of URRs 2, 4, and 5. The degree of agreement between Kt/V 2 and the mean of Kt/Vs 2, 4 and 5 is good for Kt/Vs of 1.3 or higher. URR agreements are good for URR of 65% or higher. Conclusion: In this population, hemodialysis adequacy parameters were reproducible, and an increase in the number of monthly measurements seems not to be necessary.

Justificativa: Doses inadequadas de diálise estão associadas a maior morbidade e mortalidade em pacientes com uremia terminal em tratamento hemodialítico. Atualmente os métodos mais utilizados para medir a adequação da hemodiálise baseiam-se no cálculo da depuração fracional de uréia (Kt/V) e da taxa de redução da uréia (URR). Nesse estudo avaliou-se a reprodutibilidade do Kt/V e da URR e analisou-se o número aceitável de medidas mensais destes parâmetros para determinar de forma fidedigna a adequação da hemodiálise. Métodos: Avaliamos 43 pacientes clinicamente estáveis, em cinco sessões de hemodiálise (sessões 1 a 5), durante três semanas. Três diálises consecutivas na primeira semana (sessões 1, 2, 3) e duas sessões de meio de semana, nas duas semanas subseqüentes (sessões 4 e 5). Resultados: Não houve diferença entre a média dos Kt/Vs obtidos em diálises seqüenciais (1, 2 e 3) comparada a média dos Kt/Vs obtidos em diálises no meio da semana (2, 4 e 5). O mesmo aconteceu com a URR e com os coeficientes de variação do Kt/V e da URR. Também não encontramos diferença entre uma medida mensal (Kt/V 2) e três medidas mensais (média dos Kt/Vs 2, 4 e 5). O mesmo ocorreu com a URR. A diferença entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 foi de – 0,02 unidades e entre a URR 2 em relação a média das URRs 2, 4 e 5 foi de – 0,5%. Além disso, se fizermos apenas uma medida mensal (Kt/V 2) 80% dos pacientes estarão a uma distância de no máximo 0,16 unidades abaixo da média dos Kt/Vs 2, 4 e 5 e no máximo 0,12 unidades acima. Em relação a URR 80% dos pacientes estarão a uma distância de no máximo 4,37% abaixo da média das URRs 2, 4 e 5 e no máximo 3,37% acima. O grau de concordância entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 é bom para pontos de corte do Kt/V igual ou superior a 1,3. No caso da URR a concordância é boa para pontos de corte acima de 65%. Conclusão: Concluímos que nesta população de pacientes clinicamente estáveis os parâmetros de adequação da hemodiálise mostraram-se reprodutíveis não havendo necessidade de aumentar o número de medidas mensais da quantidade de diálise ofertada. / Background: Inadequate doses of dialysis are associated with higher morbidity and mortality rates for end-stage renal disease (ESRD) patients undergoing hemodialysis treatment. Most methods aimed at measuring dialysis adequacy use the calculation of fractional clearance of urea (Kt/V) and urea reduction ratio (URR). This study evaluates the reproducibility of Kt/V and URR and analyzes the acceptable number of monthly measurements of these parameters to determine hemodialysis adequacy. Methods: We evaluated 43 clinically stable patients in five hemodialysis sessions (1 to 5) along three weeks. Three consecutive sessions were carried out in the first week (1, 2, 3), while the two other studied sessions were carried out in the middle of the week at weekly intervals (4, 5). Results: There was no difference between mean Kt/V in sessions 1, 2, and 3 and in sessions 2, 4, and 5. The same was observed for URR and the coefficients of variation for Kt/V and URR. Either differences were found between one monthly measurement (2) or three monthly measurements (mean of 2, 4, and 5) for Kt/V and URR. The difference between Kt/V 2 and the arithmetic mean of Kt/Vs 2, 4, and 5 was – 0.02 units, and between URR 2 and the mean of URRs 2, 4, and 5 was – 0.5%. When only one monthly measurement (Kt/V 2) was considered, 80% of the patients presented ≤0.16 unit below or ≤0.12 above the mean of Kt/Vs 2, 4, and 5. For URR, 80% of patients presented ≤4.73% below or ≤3.37% above the arithmetic mean of URRs 2, 4, and 5. The degree of agreement between Kt/V 2 and the mean of Kt/Vs 2, 4 and 5 is good for Kt/Vs of 1.3 or higher. URR agreements are good for URR of 65% or higher. Conclusion: In this population, hemodialysis adequacy parameters were reproducible, and an increase in the number of monthly measurements seems not to be necessary.

Justificativa: Doses inadequadas de diálise estão associadas a maior morbidade e mortalidade em pacientes com uremia terminal em tratamento hemodialítico. Atualmente os métodos mais utilizados para medir a adequação da hemodiálise baseiam-se no cálculo da depuração fracional de uréia (Kt/V) e da taxa de redução da uréia (URR). Nesse estudo avaliou-se a reprodutibilidade do Kt/V e da URR e analisou-se o número aceitável de medidas mensais destes parâmetros para determinar de forma fidedigna a adequação da hemodiálise. Métodos: Avaliamos 43 pacientes clinicamente estáveis, em cinco sessões de hemodiálise (sessões 1 a 5), durante três semanas. Três diálises consecutivas na primeira semana (sessões 1, 2, 3) e duas sessões de meio de semana, nas duas semanas subseqüentes (sessões 4 e 5). Resultados: Não houve diferença entre a média dos Kt/Vs obtidos em diálises seqüenciais (1, 2 e 3) comparada a média dos Kt/Vs obtidos em diálises no meio da semana (2, 4 e 5). O mesmo aconteceu com a URR e com os coeficientes de variação do Kt/V e da URR. Também não encontramos diferença entre uma medida mensal (Kt/V 2) e três medidas mensais (média dos Kt/Vs 2, 4 e 5). O mesmo ocorreu com a URR. A diferença entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 foi de – 0,02 unidades e entre a URR 2 em relação a média das URRs 2, 4 e 5 foi de – 0,5%. Além disso, se fizermos apenas uma medida mensal (Kt/V 2) 80% dos pacientes estarão a uma distância de no máximo 0,16 unidades abaixo da média dos Kt/Vs 2, 4 e 5 e no máximo 0,12 unidades acima. Em relação a URR 80% dos pacientes estarão a uma distância de no máximo 4,37% abaixo da média das URRs 2, 4 e 5 e no máximo 3,37% acima. O grau de concordância entre o Kt/V 2 e a média dos Kt/Vs 2, 4 e 5 é bom para pontos de corte do Kt/V igual ou superior a 1,3. No caso da URR a concordância é boa para pontos de corte acima de 65%. Conclusão: Concluímos que nesta população de pacientes clinicamente estáveis os parâmetros de adequação da hemodiálise mostraram-se reprodutíveis não havendo necessidade de aumentar o número de medidas mensais da quantidade de diálise ofertada. / Background: Inadequate doses of dialysis are associated with higher morbidity and mortality rates for end-stage renal disease (ESRD) patients undergoing hemodialysis treatment. Most methods aimed at measuring dialysis adequacy use the calculation of fractional clearance of urea (Kt/V) and urea reduction ratio (URR). This study evaluates the reproducibility of Kt/V and URR and analyzes the acceptable number of monthly measurements of these parameters to determine hemodialysis adequacy. Methods: We evaluated 43 clinically stable patients in five hemodialysis sessions (1 to 5) along three weeks. Three consecutive sessions were carried out in the first week (1, 2, 3), while the two other studied sessions were carried out in the middle of the week at weekly intervals (4, 5). Results: There was no difference between mean Kt/V in sessions 1, 2, and 3 and in sessions 2, 4, and 5. The same was observed for URR and the coefficients of variation for Kt/V and URR. Either differences were found between one monthly measurement (2) or three monthly measurements (mean of 2, 4, and 5) for Kt/V and URR. The difference between Kt/V 2 and the arithmetic mean of Kt/Vs 2, 4, and 5 was – 0.02 units, and between URR 2 and the mean of URRs 2, 4, and 5 was – 0.5%. When only one monthly measurement (Kt/V 2) was considered, 80% of the patients presented ≤0.16 unit below or ≤0.12 above the mean of Kt/Vs 2, 4, and 5. For URR, 80% of patients presented ≤4.73% below or ≤3.37% above the arithmetic mean of URRs 2, 4, and 5. The degree of agreement between Kt/V 2 and the mean of Kt/Vs 2, 4 and 5 is good for Kt/Vs of 1.3 or higher. URR agreements are good for URR of 65% or higher. Conclusion: In this population, hemodialysis adequacy parameters were reproducible, and an increase in the number of monthly measurements seems not to be necessary.

Because of a very variable geological composition of the Czech Republic, there is a various scale of all genetic types of rocks that are used for the production of crushed stone. The most often used group of rocks are effusive magmatic rocks, which represent about 34 % of crushed stone marketed (Starý et al. 2010). These rocks are used for all kinds of construction purposes including roads. The experimental material of crushed stone used in this thesis was sampled from 40 active quarries in the Czech Republic. The studied volcanic rocks originated from Neoproterozoic and Paleozoic complexes of Barrandien, Carboniferous and Permian of Krkonose Piedmont Basin, Carboniferous and Permian of Intrasudetic basin, area of ordovician Železné Hory, from the main volcanic center of Bohemian Massif in the north-west Bohemia (České středohoří Mts. and Doupov Mts.), Neovolcanic area of Czech Cretaceous basin and area of Neovolcanic East and West Sudeten. Petrographic study was carried out in a form of standard petrographic analysis of thin sections and chemical analysis, which helped inclusion of rocks to a classified systems. The whole suite of volcanic rocks was separated to five petrographic-technologic subgroups defined as: (1) rhyolites / porphyres, (2) phonolites, (3) basalts s.l., (4) spilites and (5)...

African copper PLC’s flagship is the copper producing Mowana mine located 129 km from Francistown in the North-Eastern part of the Republic of Botswana. The processing operation at Mowana is a standard flotation plant designed to produce copper concentrates from oxide, supergene, and sulphide ores. The expected average output of 16.2 tons per hour of copper concentrates has never been attained since plant commissioning. The major bottleneck has been established to be located around the crushing circuit of the Mowana production chain. The major hypotheses of this research are that performance in a crushing plant is adversely influenced by moderate and discrete changes in the process. The ultimate objective is to develop a dynamic process simulator, administered in Simulink/MATLAB® background, for application in the design of a control model utilising two crusher variables and a self-tuning control algorithm. In this research work, a process model describing the dynamic operation of an Osborn 57S gyrasphere cone crusher is investigated. Modelling of the Mowana crushing circuit is carried out by combining the steady-state and dynamic components of the crushing equipment in the Simulink/Matlab® environment. Eccentric speed (ES) and closed-side setting (CSS) are amongst the important inputs to the models. The rest of the inputs (crusher power, crusher cavity level, federate, pulley diameters, liner wear measurement, number of teeth of the pinion and bevel gear) are extracted from the data collected across the Mowana mine crushing circuit. While it has been demonstrated that the crusher CSS is the most influential controllable parameter, it has also been demonstrated that crusher capacity and power can be used effectively to optimise the circuit. The use of crushing power and cavity level control is suitable for the crushing circuit since the crushers are running on a constant ES and the CSS is set and reset manually. The outcome of the study presents an insight into the optimization of the Mowana mine crushing circuit through the design of a self-tuning controller for the cone crusher and for prototyping, parameters of a PID controller were determined in the Simulink/MATLAB® environment. The simulation involved the optimisation of the control model as a function of the cavity level of and the power drawn by the cone crusher. A self-tuning control algorithm at PLC and SCADA level of control was then tested. This formed the simulations and training platform. The outcome of the simulations carried out in this research needs to be validated against the real Mowana crushing process control upgrade. This will then inform the modifications and recommended crusher motor resizing exercise to be implemented. / Electrical and Mining Engineering / M. Tech. (Engineering: Electrical)