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Student Number : 9900280X - MSc (Eng) dissertation - School of Chemical and Metallurgical Engineering - Faculty of Engineering and the Built Environment / The flow characteristics of an on-line analyser were measured using a stimulus – response technique. The analyser was developed for monitoring homogeneous catalyst concentrations in a non-aqueous solution and it was considered important to limit dispersion effects between sample injection and measuring points. Various tube lengths between these points were used and the system was operated over a range of flow rates. The detectors employed were electrochemical in nature and of two different designs. The residence time distributions of the system were determined experimentally and analysed by the method of moments and frequency techniques. As expected dispersion of the sample decreased as tube length decreased and flow rate increased. An attempt was made to fit the experimental results to the axially dispersed plug flow model. This was only successful over a limited range of the variables.

Ice jams have caused serious hazards such as floods in northern countries. Despite several studies focused on river ice jams, a lack of research has been identified in the existing literature to analyze impacts of an ice jam on turbulent flow characteristics. Thus, this research attempts to address this knowledge gap. A better comprehension of flow features beneath an ice jam will help river ice engineers to reduce economic, environmental, and ecological damages. Technical difficulties and safety concerns limit data collection in ice jam field studies. Therefore, a physical model of a river ice jam was constructed in the Hydraulics Research & Testing Facility at the University of Manitoba. Two scenarios were proposed to simulate an ice jam. The first scenario was to use a basic model with constant upstream and downstream water depth. The second scenario was developed as an extension of the first scenario, with a modified setup to allow the upstream water depth to be greater than the downstream water depth. This was done to increase similarity with the real ice jam in nature and improve the results. For the second scenario, different roughness ratios of channel bed to ice jam were defined. Experiments were conducted to quantify the turbulent flow characteristics including streamwise velocity and streamwise turbulence intensity distribution beneath the ice jam. The flow velocities were measured at different locations beneath the ice jam using an acoustic Doppler velocimeter. The turbulence intensities and bed shear stresses were calculated using the measured velocities. The results indicated that the flow velocity and turbulence intensity were a function of the streamwise location beneath the ice jam as well as the roughness of the bed and ice jam. Significant changes were observed in the velocity and turbulence intensity profiles where the boundaries were fully rough, which could influence an ice jam formation, sediment concentration and water quality, as well as river bed deformation. It is believed that the results from this research will improve our fundamental understanding of flow beneath an ice jam, and can be used for validation of subsequent ice jam numerical models. / October 2016

<p> Experimental investigations have been conducted for an Electrohydrodynamically enhanced capillary evaporator (EHD-ECE) for enhancement of liquid evaporation, hence the flow rate. A capillary evaporator has a liquid channel inlet and a vapour channel exit. Inside the evaporator is a porous media that separates the liquid and vapour, which is also responsible for the capillary action. When an external electric field is applied inside the liquid side of the evaporator, the capillary action may be enhanced due to external body forces. Voltage was applied to the 3.lmm electrode, in the centre axis of the evaporator liquid channel. The environmentally friendly HFC-134a is used as the working fluid. The coaxial cylindrical evaporator centre is liquid filled and surrounded by a porous polyethylene wick, where the vapour channels are located on the other side of the wick. Heat is applied to the outer diameter of the evaporator. Experiments were conducted for applied heat loads from 0 to 80W and applied electric fields of de voltages from 0 to -5kV and 5kV, as well as frequencies ranging from 5-200Hz with applied pulse voltages of -IOkV and 5kV. Thermal temperatures of the liquid inlet, vapour exit, and evaporator wall, pressure difference across the evaporator, system pressure and liquid flow rates are measured and analysed. </p> <p> The experimental results show that the vapour flow rate increases with increasing applied voltages and enhancement up to a maximum of 202% was achieved when 5kV de was applied with a heat input of 80W. The polarity of the applied voltage had only a slight effect as slightly higher flow rate enhancements were observed. The vapour flow rate was also enhanced for applied pulse voltage, where the vapour flow rate increased with increasing frequencies between 50Hz to 200Hz. </p> <p> With the application of de and pulsed electric fields, the vapour flow rate due to the external body forces acting on the liquid-vapour interface are enhanced. Future work is required to fully understand the phenomena and more optimization studies are required for the EHD-CPL. </p> / Thesis / Master of Science (MSc)

The linear stability analysis of Huang [1995] has been adapted to ignore the effects of swirl, and to allow calculation of the eigenvalues and eigenfunctions for integer, fractional, and multiple modes of excitation. The investigation was intended to be exploratory; to gain the best possible insights into the flow characteristics from analysis of the linearized Euler equations. All of the azimuthal modes investigated (one-half, one, three-halves, and two) were found to lead to the continuous, helical, vortical structure evolution in the streamwise direction of the jet. The analysis for fractional modes of excitation predicted aphysical behavior near the jet center that has been attributed to a unresolved questions in the mathematical analysis of the problem. Multiple mode excitation at the axisymmetric mode and one or more azimuthal modes were found to result in un-even, periodic, vortex-ring growth in the shear layer. An argument was presented for the axisymmetric mode (m=O) resulting in the highest levels of entrainment for all integer, fractional, and multiple modes of excitation. Finally the importance of the azimuthal component of vorticity in the entrainment process was identified. / Master of Science

Yes / This study presents the experimental results of the flow characteristics, such as the flow adjustment, velocity profiles, mixing layer, and the momentum exchange, in the partially vegetated channel with homogeneous and heterogeneous layouts. Three cases are considered, including two homogeneous canopies with uniform sparse and dense vegetation patches respectively, and a heterogeneous canopy consisting of alternating patches of both densities. Results show that heterogeneous canopy requires a longer adjustment distance to reach the quasi-equilibrium region, compared with the homogenous canopy of the same density. In heterogeneous canopy flow, the mixing layer width and the momentum thickness fluctuates with the alternation of vegetation density. The increased values for these two parameters compared to those values for the homogeneous canopies indicate that the greater resistance and momentum loss occur for the heterogeneous layout. A wavy region of the enhanced in-plane turbulence kinetic energy (TKE) is observed in the heterogeneous canopy, suggesting a comparatively more chaotic flow condition, whereas the contours of in-plane TKE are smooth in homogeneous canopies. The presence of the coherent structures in heterogeneous canopy is identified by spectral analysis and the quasi-periodic fluctuations of velocities. The Reynolds stress associated with the coherent structures is found to be the dominator of the contribution to the total Reynolds stress. The comparison between the homogenous canopies of different density is also conducted. These results will be of practical importance for the design of vegetation layouts in water ecological restoration projects and for river management. / National Natural Science Foundation of China (grant numbers 52020105006 and 11872285) and the Open Funding of State Key Laboratory of Water Resources and Hydropower Engineering Science (WRHES), Wuhan University (Project number 2018HLG01)

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The present series of in vivo experiments in healthy subjects, were performed to investigate wall stiffness in peripheral vessels and how this modality adapts to iterative increments or sustained reductions in local intravascular pressures. Vascular stiffness was measured as changes in arterial and venous diameters, and in arterial flow, during graded increments in distending pressures in the vasculature of an arm or a lower leg. In addition, effects of intravascular pressure elevation on flow characteristics in veins, and on limb pain were elucidated. Arteries and veins were stiffer (i.e. pressure distension was less) in the lower leg than in the arm. The pressure-induced increase in arterial flow was substantially greater in the arm than in the lower leg, indicating a greater stiffness in the arterioles of the lower leg. Prolonged reduction of intravascular pressures in the lower body, induced by 5 wks of sustained horizontal bedrest (BR), decreased stiffness in the leg vasculature. BR increased pressure distension in the tibial artery threefold and in the tibial vein by 86 %. The pressure-induced increase in tibial artery flow was greater post bedrest, indicating reduced stiffness in the arterioles of the lower leg. Intermittent increases of intravascular pressures in one arm (pressure training; PT) during a 5-wk period decreased vascular stiffness. Pressure distension and pressure-induced flow in the brachial artery were reduced by about 50 % by PT. PT reduced pressure distension in arm veins by 30 to 50 %. High intravascular pressures changed venous flow to arterial-like pulsatile patterns, reflecting propagation of pulse waves from the arteries to the veins either via the capillary network or through arteriovenous anastomoses. High vascular pressures induced pain, which was aggravated by BR and attenuated by PT; the results suggest that the pain was predominantly caused by vascular overdistension. In conclusion, vascular wall stiffness constitutes a plastic modality that adapts to meet demands imposed by a change in the prevailing local intravascular pressure. That increased intravascular pressure leads to increased arteriolar wall stiffness supports the notion that local pressure load may serve as a “prime mover” in the development of vascular changes in hypertension. / medicine doktorsexamen QC 20101109

In considering methods of reducing the emission of carbon dioxide; there is a growing interest for use of wind power at domestic building in U.K. But the technology of wind turbines development in building environment is more complicated than in open areas. Small wind turbines in suburban areas have been reported as having unsatisfactory energy output, but it is not clear whether this is due to insufficient wind resource or low turbine efficiency. The aim of this research is to discover whether the wind resource in suburban areas is large enough for small wind turbines to produce a useful energy output.Historical wind data and manufacturers' turbine characteristics were used to estimate the hourly wind speed and energy output for different U.K. cities, terrain zones and turbines. It was found that for turbines at 10 m height in suburban areas and depending on city, the annual wind energy conversion efficiency ranged from about 20 to 40%, while the number of turbines required to produce the annual average electricity consumption of a UK dwelling ranged from about 6 for the smallest turbine (5.3 m² rotor area) to about 1 for the largest (35.26 m² rotor area).This analysis was based on average conditions, but the wind speed near buildings can vary considerably from one point to another. In order to predict the performance of wind turbines more accurately, the atmospheric boundary layer (ABL) of suburban areas was simulated in both CFD and wind tunnel models, and models of groups of semi-detached and terraced houses were set in this ABL. It was found that at 10 m height in the area of the houses, the turbulence intensity was too high for satisfactory operation of wind turbines (19 to 35%) while the mean velocity at different points ranged from 86 to 108% of the 10m reference velocity. At 30m height the turbulence intensity was satisfactory (less than 19 %), while the mean velocity ranged from 92 to 103 % of the 30 m reference velocity. It is concluded that for wind turbines in suburban areas, at 10 m height the wind speed is too low and the turbulence is too high for satisfactory performance, while at 30 m height the wind speed is much higher and the turbulence is low enough.

V dnešní době se chirurgové zajímají o vliv viskozity kostních cementů na jejich penetraci do kosti při úplné kostní náhradě. Penetrace cementu závisí na jeho viskozitě, času vsunutí protézy, době tvrdnutí, atd. Viskozita je určena chemickým složením, teplotou a poměrem monomeru a prášku. V této práci bude porovnávána viskozita a penetrace vysoko- a nízko- viskózních cementů. Viskozita bude měřena dvěma modely. V prvním modelu je hrot s konstantní rychlostí vtlačován do cementu. V druhém modelu je cement vytlačován z kapiláry konst. rychlostí. Penetrace cementu po vstříknutí do kosti bude měřena pomocí rentgenu.