Heat exchangers are used in a wide variety of industrial applications. Augmentation of heat transfer can realize a reduction in heat transfer size and increase the effectiveness and efficiency of heat exchangers. Heat transfer can be enhanced with various methods where the turbulence of the fluid flow is enhanced: by adding ribs, grooves or steps to the channel wall, using helical inserts, or by adding bluff bodies in the channel flow. By using these methods, there is also an increase in pressure drop penalty and larger pumping power is required to achieve the same flow rate. Circular cylindrical bluff bodies have been found to have smaller drag coefficients than square, rectangular or triangular cylindrical bluff bodies in the channel flow. Heat transfer and pressure drop experimental tests were done for eight different circular cylindrical cross-bar arrays at 15 different Reynolds numbers, in the range of 640 to 12 500. Eight different cross-bar configurations were tested: the cylinder diameter to pitch ratios were, d/p = 0.025, d/p = 0.05, d/pi=i0.1 and d/p = 0.2, and the angle to the flow direction, was θ = 90° and θ = 45° for each of the four different diameter-to-pitch ratios. Transient CFD simulations were done using Ansys fluent for d/p = 0.05 and d/p = 0.2, for θ = 90°, at Reynolds numbers 920 and 9 700, to analyze the secondary flow structures in the wake of the cylinders, partly responsible for the heat transfer and pressure drop increase in the channel flow in comparison to the smooth channel. The k-Ω shear stress transport (SST) model was used for the simulations. A mesh dependence study was done for spatial discretization, temporal discretization and validated against the experimental setup. The pressure drop gradient was found from the test data for the hydraulically developed part of the test section to calculate the friction factors. With an increase in Reynolds number, the friction factors decreased until reaching an asymptotic value for all the cross-bar configurations. For θi=i90° the friction factors were larger than for θ = 45° for the same d/p ratio and Reynolds number. With an increase in d/p, the friction factors increased. The largest measured friction factor was f = 0.3, for configuration d/p = 0.2, θ = 90°, at Re = 640 and the smallest measured friction factor f = 0.02, for d/pi= 0.025, θ = 45°, at Re = 12 500. The friction factor ratio was then used to quantify the pressure penalty for using cylindrical cross-bars in the channel flow to enhance heat transfer. The maximum friction factor ratio, f/f0 = 16.7 occurred at Re = 9 700, for d/pi=i0.2, θ = 90° and the minimum friction factor ratio, f/f0 = 2.1, at Re = 640, for d/pi=i0.025, θ = 45°. The average Nusselt numbers were then calculated using the spatial integral average of the local Nusselt numbers. With an increase in Reynolds number, there was an increase in the average Nusselt number for all the cylindrical cross-bar configurations. For larger d/p ratios and θ = 90° cases, the average Nusselt numbers were larger than for smaller d/p ratios and θ = 45°. The largest average Nusselt number was Nuavg = 66.3, at Re = 9 700 for d/p = 0.2, θ = 90° and the smallest average Nusselt number, Nuavg = 8.7, at Re = 640 for d/p = 0.025, θ = 45°. The Nusselt number ratio could then be used to quantify the heat transfer enhancement of the cylindrical cross-bar channel to that of the smooth channel, where the largest Nusselt number ratio was, Nuavg /Nu0,avg = 3.3, for d/p = 0.2, θ = 90°, at Rei=i3 000 and the smallest Nuavg /Nu0,avg = 1.1, for d/p = 0.025, θ = 45°, at Re = 640. The CFD results concluded that the pressure drop increase and heat transfer enhancement were caused by the flow acceleration, flow separation, eddy formation, vorticity increase, and boundary layer deformation next to and behind the cylinders. The Strouhal number for the larger d/p ratios suggested that the unsteadiness in the flow is higher for the cylinder arrays with a larger diameter, increasing both the heat transfer enhancement and friction factor in comparison with the smaller diameter cylinder arrays. Finally, the thermal performance coefficients could be calculated by using the friction factor ratios and Nusselt number ratios. The thermal performance coefficient combines the effects of the heat transfer and pressure penalty increase. The thermal performance coefficients increased from Re = 640 until Rei=i3 000 after which it decreased with an increase in Reynolds number. This is because the pressure penalty starts to outweigh the heat transfer increase caused by the turbulators. The largest thermal performance coefficient was η = 1.6, for d/p = 0.025, θ = 45°, at Re = 3 000, and the lowest, η = 0.79, for d/p = 0.05, θ = 90°, at Re = 640. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2021. / Mechanical and Aeronautical Engineering / MEng (Mechanical Engineering) / Unrestricted

The South African Schools Act 84 of 1996 prescribes how schools should manage their finances and involve their stakeholders in financial management decision-making. The relevant literature reveals that principals in many schools situated in township and rural areas play a dominant role in the financial management of their schools which is contrary to the prescriptions of the South African Schools Act. This study aimed to identify financial management decision-making processes utilized in fee-paying public primary schools, the factors that influence financial management decision-making and the role and influence of individual stakeholders in financial management decision-making. The study followed a qualitative research approach with a multiple case study research design. Five fee-paying public primary schools were purposively selected. Participants included governing body chairpersons, principals and financial managers of the schools. Data was collected by means of semi-structured interviews and document analysis. The findings from the data suggest that financial management decision-making processes utilized in fee-paying public primary schools are: needs analysis, budget drafting and procurement processes. The study also reveals that members of school governing bodies (SGB) in fee-paying schools situated in affluence areas are educated professionals who, as required by the South African School Act, exert a strong influence in financial management decision-making in schools. / Dissertation (MEd)--University of Pretoria, 2017. / Education Management and Policy Studies / MEd / Unrestricted

The placenta of the anthocerote, Dendroceros tubercularis Hatt., consists of long and branched haustorial cells, that arise from the foot and gametophyte transfer cells. Both cell types contain electron‐dense vacuolar deposits that were digested by pronase and therefore are assumed to be protein. These deposits were negative to the PATAg test for carbohydrates. Protein bodies were also found in the parenchyma cells of the foot and younger meristematic cells at the base of the capsule. Vacuolar deposits of osmiophilic material in the gametophyte cells external to the placenta were stained non‐specifically with PATAg method and were not affected by pronase. The haustorial cells have pleomorphic plastids lacking starch and a thylakoid system, whereas the transfer cells have well developed chloroplasts. No pronase‐sensitive material was detected in the apo plastic space separating gametophyte and sporophyte cells. These results suggest that protein is synthesized in the haustorial cells, perhaps from precursors provided by transfer cells, and is then transferred, via plasmodesmata, to the parenchyma cells of the foot and eventually to the cells of the growing capsule.

Over the past 25 years, advances in the field of turbulence modeling have been made in an effort to resolve more scales, preserving unsteadiness within a flow. In this research two hybrid models, Scale-Adaptive Simulation (SAS) and Stress-Blended Eddy Simulation (SBES) are implemented in solving the highly unsteady flow over a rotating arrangement of three cylinders. Results are compared to those from wind tunnel experiments carried out at North Dakota State University. Both models show close agreement with first and second order turbulence quantities, and SBES shows much greater flow structure detail due to its ability to resolve smaller scales. The Strouhal number for the flow is found to be a function of the rotational speed of the arrangement with von Karman-like structures resulting from each cylinder's wake over a full rotation. SAS shows a constant computational cost as Re increases while the SBES's computational cost increases relatively linearly.

La presente investigación abordará el análisis de la gobernanza y el desempeño de las FDN en Perú a partir de la percepción de los atletas de alto rendimiento que participaron en los Juegos Panamericanos de Lima 2019. El objetivo general es evaluar si existe correlación entre dichas variables a partir de la percepción de este grupo de interés. Para lograr los distintos objetivos planteados en este trabajo se definió un método mixto con un diseño secuencial en el se tuvo una primera etapa cualitativa y una segunda cuantitativa. En la etapa cualitativa se consultó a expertos en la gestión de una FDN a quienes se les presentaron los principales hallazgos de la literatura revisada para organizaciones internacionales. A partir de estos resultados, se pudieron identificar las dimensiones de las variables a analizar y proponer afirmaciones para cada una apartir de las cuales se elaboró un cuestionario con una escala de Likert. La encuesta se aplicó a 151 atletas que representaron al Perú en la competencia señalada. Los resultados de la etapa cualitativa evidencian que no hay consenso en la literatura internacional sobre la forma de evaluar la gobernanza y el desempeño en organizaciones deportivas y, de manera particular, en federaciones deportivas nacionales. Sin embargo, frente a la propuesta que se derivó de la revisión literaria, hubo consenso sobre las dimensiones propuestas. Los resultados de la etapa cuantitativa evidencian que hay una correlación positiva moderada entre la percepción de la gobernanza y la percepción del desempeño. Con respecto a las dimensiones de gobernanza, podemos afirmar que de las 13 afirmaciones sólo hubo 3 de ellas en las que menos del 40% estaba de acuerdo con dichas afirmaciones que fue una de las hipótesis propuesta. En el caso del desempeño, se puede afirmar que en las 3 afirmaciones de la dimensión desempeño administrativo menos del 40% de los atletas están de acuerdo con las mismas. La muestra de 151 atletas fue elegida por conveniencia y no constituye una muestra representativa de la población por lo que los resultados no pueden ser extrapolados a la misma. Además, en futuras investigaciones se puede complementar la percepción de los atletas con un indicador objetivo para cada una de las dimensiones identificadas. El aporte para un mejor entendimiento teórico sobre la gobernanza y el desempeño de una FDN será de utilidad para futuras investigaciones que se hagan sobre este tipo de organizaciones deportivas a nivel internacional. / Tesis

Magister Commercii - MCom / This thesis provides an in-depth explorative case study of the relationship between electoral management and civil rights, using the 2013 Tlokwe By-Elections in South Africa as a case study. The central question in this thesis was: what are the implications of the Tlokwe Ruling on South Africa’s electoral democracy? This topic is extremely important to the field of democracy and elections, as electoral processes become ever more essential in allowing citizens to access free and fair elections. Without the ability to access free and fair elections, the power of citizens to hold leaders accountable is diminished. The study used the framework provided by Diamond and Morlino on the quality of democracy because it contains useful normative values of a democracy and assisted in providing a lens by which to view and analyse elections in a democratic regime.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 120-121. / by Pierre Haren. / M.S.

No description available.

Superhydrophobic surfaces are a class of surfaces that have a microscale roughness imposed on an already hydrophobic surface, akin to a lotus leaf. These surfaces have been shown to produce significant drag reduction for both laminar and turbulent flows of water through large and small-scale channels. The goal of this thesis was to explore how these surfaces alter the vortex shedding dynamics of a cylindrical body when coated on its surface, thus leading to an alteration in drag and lift on these surfaces. A cylindrical body was chosen as it is a very nice representative bluff body and sets the stage for predicting the behavior of hydrofoils and other bluff bodies under flow with a slip boundary condition. In this work, a series of experiments were performed which investigated the effect of superhydrophobic-induced slip on the flow past a circular cylinder. In these experiments, circular cylinders were coated with a series of superhydrophobic surfaces fabricated from PDMS with well-defined micron-sized patterns of surface roughness or random slip surfaces fabricated by sanding Teflon cylinders or spray painting superhydrophobic paint on a smooth cylinder. The presence of the superhydrophobic surface was found to have a significant effect on the vortex shedding dynamics in the wake of the circular cylinder. When compared to a smooth, no-slip cylinder, cylinders coated with superhydrophobic surfaces were found to delay the onset of vortex shedding and increase the length of the recirculation region in the wake of the cylinder. For superhydrophobic surfaces with ridges aligned in the flow direction the separation point was found to move further upstream towards the front stagnation point of the cylinder and the vortex shedding frequency was found to increase. For superhydrophobic surfaces with ridges running normal to the flow direction, the separation point and shedding frequency trends were reversed. The vortices shed from these surfaces were found to be weaker and less interlaced leading to reduced circulation and lift forces on these cylinders. The effect of slip on bluff bodies and separating flow was dealt with in detail in this thesis and the results could be used to predict the impact of these surfaces on the flow past hydrofoils which combine skin friction dominated flow with separating flow.

The grapefruit plant, Citrus paradisi, tends to accumulate high levels of flavonoid glycosides such as flavanones and flavones. Flavonoids have a vast array of important functions in plants and also in humans. Glucosyltransferases (GTs) are enzymes responsible for glucosylation reactions. In our pursuit to study the structure and function of flavonoid GTs, we have used molecular approaches to identify, clone, express, and functionally characterize the enzymes. This research was designed to test the hypothesis that PGT3 is a flavonoid glucosyltransferase and is subject to biochemical regulation. PGT3 has been tested for GT activity with compounds representing subclasses of flavonoids as well as some simple phenolics. Results indicate GT activity with 6 substrates, p-hydroxybenzoic acid, vanillin, vanillic acid, p-hydroxyphenylpyruvate, gentisic acid, and catechol. A second project designed to clone putative PGT8 into the Pichia expression system has been completed.