This Thesis presents a design innovation in arthroscopic forceps. Based on surveying the subject-matter literature on arthroscopic surgery of the knee, design changes are proposed to alter the cutting geometry of the functional end of the instrument to improve its utility. The proposed changes are imple-mented in a prototype, which is then compared with the current design. The comparison is made by testing the functioning of the instrument and the force required to shear the test material.

This thesis deals with centrifugal pump impeller design for given parameters. This pump impeller design consists of the calculation of basic dimensions, the meridional flow channel design and blade design. Complete design of the pump impeller is afterwards simulated in CFD programme.

This thesis is concerned with the topic of Pumps with crew centrifugal impeller. Thanks to the benefits such as free passage and efficiency there are many practical applications of these products. Despite this fact there is only few manufacturers dealing with them what results in lack of research and available information in the area. In order to fill the gap, this thesis aims to propose hydraulic of screw centrifugal impeller to the specified parameters. The impeller with a single moving blade will be designed for pumping heavily polluted water and hardly pumpable liquids. Blade will be balanced together with the rotor, while the emphasis will be placed on the highest free passage of impeller. The theoretical part of the thesis summarizes literature on the subject, practical part deals with the calculations and adjustments pointing to a concrete proposal. Parameters of designed hydraulics were verified using stationary calculations using MRF model in FLUENT. As a results, two possible solutions are offered.

The master´s thesis discuss about design and manufacture of blade stabilizer. It will be sets limit conditions for design blade and subsequent analysis of effects of stress and strain on the rod of blade and assembly of the stabilizer in various settings. For manufacturing of blade it will design materiál of the blank, manufacturing proces and machining conditions with the choice of cutting tools nad cutting machine. In conclusion will be comparison blades from formulas of last years from monopost Dragon 2 to Dragon 6.

This diploma thesis describes design of blade geometry of swirl turbines with different blade row density for given parameters Q11 = 1,9 [m3s-1], n11 = 170 [min-1], H=2,5 m, and =0,8. Goal is to found out differences between designs with high count of runner blades and design with fewer blades. Comparison of computed characteristics of three, seven and nine bladed runners is given.

Uppsatsens syfte är att undersöka hur filmfotografen Roger Deakins komponerar och ljussätter bilder för att skapa djup och trovärdighet i ett tvådimensionellt medium. Teori kring förmedlande av djup, form, textur samt separation används i en analys av utvalda bilder från filmen Blade Runner 2049 (2017). Teorin kopplas samman med begrepp inom bildkomposition och ljussättning för att skapa en förståelse kring hur Deakins åstadkommit resultaten. I analysen etableras en användning av materia i luften (dimma, rök, regn), kameraplacering gentemot huvudljus, ett välkomnande av skuggor samt ett förhållningssätt till kompositionella regler.

Solution-processed organic field effect transistors (OFETs) have emerged in recent years as promising contenders to be part of electronic and optoelectronic circuits owing to their compatibility with low-cost high throughput roll-to-roll manufacturing technology. The stringent performance requirements for OFETs in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require the performance of single crystal-based OFETs, but these suffer from major scale-up challenges. To achieve device performance approaching that of single crystals with scalable, high throughput and industry-compatible solution coating of OFETs requires understanding and ultimately controlling the crystallization of organic semiconductors (OSCs), and producing very low defect-density thin films. In this thesis, we develop an understanding of the process-structure-property-performance relationship in OSCs that bring fresh insights into the nature of solution crystallization and lead to novel ways to control OSC crystallization, and finally help achieve fabrication of high-performance OFETs by scalable, high throughput and industry-compatible blade coating method. We probe the solution crystallization of OSCs by employing a suite of ex & in situ characterization techniques. This leads us to an important finding that OSC molecules aggregate to form a dense amorphous intermediate state and nucleation happens from this intermediate state during blade coating under a wide window of coating conditions. This phenomenon resembles the so-called two-step nucleation model. Two-step nucleation mediates the crystallization of a wide range of natural and synthetic products ranging from soft materials, such as proteins, biominerals, colloids and pharmaceutical molecules, to inorganic compounds. We go on to show that this nucleation mechanism is generally applicable to achieve formation of high-quality polycrystalline films in a variety of small molecule OSCs and their polymer blends. This phenomenon results in highly textured and well-connected domains, which exhibit reduced interfacial and bulk trap-state densities, helping raise the carrier mobility by one to two orders of magnitude in OFETs in comparison to direct nucleation. We extend the understanding developed for solution crystallization of various acenes and thiophene-based small molecule OSCs to the high-performance benzothieno-benzothiophene (BTBT) based small molecule OSCs. On this end, we develop protocols to fabricate high-quality thin films of BTBT based OSCs by blade coating at industrially compatible coating speeds (>100 mms-1). These films show massive single-domains with very few apparent defects when crystallized via multiple liquid-crystalline phases in two-step nucleation conditions, resulting in an average carrier mobility of ~10 cm2V-1s-1. To sum up, this thesis develops an understanding of OSC solution crystallization and efficient protocols to control polycrystalline thin film quality for high-performance OFETs. These protocols involve a combination of two-step nucleation pathway, solvent mixtures, polymer blends and device-manufacturing conditions. Our efforts enable to realize high-performance OFETs based on high-quality polycrystalline OSC thin films at industry-compatible conditions.

Tidal energy represents a promising resource for the future energy mix. For harnessing tidal currents free stream horizontal axis turbines have been investigated for some years. The acting physics is very similar to the one of horizontal axis wind turbines, with the additional phenomenon of cavitation, which causes performance reduction, flow induced noise and severe damages to the turbine blade and downstream structures. The paper presents an enhanced semi-analytical model that allows the prediction of the performance characteristics including cavitation inception of horizontal axis tidal turbines. A central component is the well-known blade element momentum theory which is refined by various submodels for hydrofoil section lift and drag as a function Reynolds number and angle of attack, turbine thrust coefficient, blade hub and tip losses and cavitation. Moreover, the model is validated by comparison with comprehensive experimental data from two different turbines. Predicted power and thrust coefficient characteristics were found to agree well with the experimental results for a wide operational range and different inflow velocities. Discrepancies were observed only at low tip speed ratios where major parts of the blades operate under stall conditions. The predicted critical cavitation number is somewhat larger than the measured, i.e. the prediction is conservative. As an overall conclusion the semi-analytical model developed seems to be so fast, accurate and robust that it can be integrated in a future workflow for optimizing tidal turbines.

This dissertation proposes hybrid models for (i) diagnosis and (ii) remaining useful life estimation of a single fatigue crack in a low-pressure turbine blade. The proposed hybrid methods consist of physics-based methods and data-driven methods. In this dissertation, blade tip timing is used to measure the relative tip displacement of a rotor blade. The natural frequency of the blade is determined by detecting the critical speeds of the blade using a newly derived least squares spectral analysis method. The method shares its origin from the Lomb-Scargle periodogram and can detect resonance frequencies in the blade’s displacement while the rotor is in operation. A Campbell diagram is then used to convert the critical speed into a natural frequency. Two kinds of shaft transients are considered, a run-up run-down crossing the same critical speed, is used to test the new method. This dissertation shows that the relative displacement of the blade tip is comparable to those simulated from an analytical single degree of freedom model. It is also shown that the newly proposed resonance detection method estimates the natural frequency of the blade to a high degree of accuracy when compared to the measurements from a modal impact hammer test. The natural frequency obtained from the real time measurement is then used in a pre-constructed hybrid diagnostics model. The diagnostics model provides a probability density function estimation of the surface crack length given the measured natural frequency. A Gaussian Process Regression model is trained on data collected during experiments and finite element simulations of a fatigue crack in the blade. The final part of this dissertation is a sequential inference model for improving the estimation of the crack length and the prediction of the crack growth. The suggested model uses an unscented Kalman filter that improves estimations of the crack length and the rate of crack growth from Paris’ Law coefficients. The model is updated each time a diagnosis is performed on the blade. The RUL of the blade is then determined from an integration of Paris’s Law given the uncertainty estimates of the current damage in the blade. The result of the algorithm is an estimation of the remaining number of cycles to failure. The algorithm is shown to improve the overall estimation of the RUL; however, it is suggested that future work looks at the convergence rate of the method. / Dissertation (MEng)--University of Pretoria, 2019. / Eskom Power Plant Engineering Institute (EPPEI) / Mechanical and Aeronautical Engineering / MEng / Unrestricted

During papermaking, the internal structure of the fibrenetwork constituting the paper is to a dominating extentdetermined in the forming zone of the paper machine. Thisthesis is aimed at studying the pressure distribution in bladeforming sections, which is commonly considered to be a keyquantity of the process. Previous work has provided insight into the physics ofdifferent devices employed in blade forming. However, there hasbeen a lack of models enabling studies of the effects of theinteraction between different components on the pressuredistribution. In the thesis, a model is presented for a genericblade forming section consisting of three blades. The positionsof two of the blades are fix, and in between them is located asuction box. The third blade is applied by a prescribed forceto the opposing wire, in a position facing the suction box. Themodel admits the study of the interaction between the pulsesfrom the different blades in the blade/counterbladeconfiguration, and between the pulses and one-sidedsuction. The wires are modelled as tensioned and perfectly flexibleEuler-Bernoulli beams of negligible mass. The suspension istreated like an inviscid fluid. Consideration is taken to theinfluence of fibre deposition on the permeability of thefabrics. By assuming the ratio between the length scales in thethickness direction and the machine direction to be small, aquasi one-dimensional model is obtained. For maximum flexibility, the model domain is divided intomodules. Each module is solved individually using a finitedifference based discretisation. The solutions for thedifferent modules are matched with each other iteratively. A comparison with published results for a single bladeindicates that the model can be used to obtain qualitativelycorrect predictions of the pressure distribution. New resultsinclude a series of calculations showing the non-trivialinteraction between the pressure pulses when the blades arepositioned successively closer together, the effects of suctionon the pressure pulse generated by a blade applied to theopposing wire, and how blades of modest curvature do notnecessarily stay in contact with the fabric along their fullwidth and the implication of this on the pressure gradient. <b>Descriptors:</b>fluid mechanics, blade forming, pressuredistribution, suction, interaction, permeable fabric,modules / NR 20140805