Browsing by Author "Van der Merwe, Schalk Willem"

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    A MEMS based valveless micropump for biomedical applications
    (Stellenbosch : University of Stellenbosch, 2010-03) Van der Merwe, Schalk Willem; Groenwold, A. A.; Thiart, G. D.; Loveday, P. W.; University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The valveless micropump holds great potential for the biomedical community in applications such as drug delivery systems, blood glucose monitoring and many others. It is also a critical component in many a lab-on-a-chip device, which in turn promises to improve our treatment and diagnosis capabilities for diseases such as diabetes, tuberculosis, and HIV/AIDS. The valveless micropump has attracted attention from researchers on the grounds of its simple design, easy manufacturability and sensitive fluid handling characteristics, which are all important in biomedical applications. The pump consists of a pump chamber with a diffuser and nozzle on opposing sides of the pump chamber. The flow into the diffuser and nozzle is induced by an oscillating piezoelectric disc located on top of the pump chamber. The nozzle and diffuser rectify the flow in one direction, due to different pressure loss coefficients. The design process however is complex. In this study, we investigate the characteristics of a diffuser / nozzle based micropump using detailed computational fluid dynamic (CFD) analyses. Significant parameters are derived using the Buckingham-Pi theorem. In part based on this, the respective shapes of the diffuser and of the nozzle of the micropump are selected for numerical investigation. Hence the influence of the selected parameters on the flow rate of the micropump is studied using three-dimensional transient CFD analyses. Velocity profiles from the CFD simulations are also compared to the Jeffery-Hamel solution for flow in a wedge shaped channel. Significant similarities exist between the data and the predicted Jeffery-Hamel velocity profiles near the exit of the diffuser. Three different diffuser geometries were simulated at three frequencies. The flow rate and direction of flow are shown to be highly sensitive to inlet and outlet diffuser shapes, with the absolute flow rate varying by as much as 200% for the geometrical perturbations studied. Entrance losses at both the diffuser inlet and nozzle inlet appear to dominate the flow resistance at extremely laminar flow conditions with the average Reynolds number of Reave ≈ 500.
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    n Odontometriese studie van tandkroondimensie en die gebruik hiervan in 'n gemengde gebitanalise
    (Stellenbosch : Stellenbosch University, 1990) Van der Merwe, Schalk Willem; Stellenbosch University. Faculty of . Dept. of .
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    'n Ondersoek na kinderteater as 'n moontlike tersiere toneelspelonderrigmeganisme
    (Stellenbosch : Stellenbosch University, 2020-12) Van der Merwe, Schalk Willem; Du Preez, Petrus; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Drama.
    ENGLISH ABSTRACT: This study investigates the current actor-training approach for students in South Africa and how this training is presented at tertiary level. The starting point for the study is the Drama Department, Stellenbosch University. Various approaches to actor-training elements are initially compared to international trends. The term integration was further investigated to create a working definition for the study. Subsequently, the successful level of integration of various actor-training elements is investigated. As an approach to this investigation, the Stanislavski system is examined in the light of the exaggerated acting style and conventions of children's theatre. Following this, various research activities were executed. Art-based research is used as a paradigm for these research activities and the relationship between Research Led Practice and Practice Led Research is applied. Self-reflective data was collected and artistically presented as exegesis in the thesis. Research activity 1 has delineated the term children's theatre, including the conventions and style of the theatrical form, so that it can be explored in practice. The Stanislavski system in Research Activity 2 was researched and tested through the theoretical framework applied within practice. Various components of the system as an approach to actor-training are emphasized. From Research Activity 2, two actor-training models are created (in Research Activities 3 and 4, respectively) to test an approach to the successful integration of actor-training elements within an exaggerated acting style. The research and methodological approach has led to the application of the theories being highlighted, in that it identifies, addresses and improves the successful level of integration during acting. Although the Stanislavski system has been used as an approach, other approaches can also be used. Children's theatre as an exaggerated acting style can also be replaced with other exaggerated acting styles, such as the farce.
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    'n Ondersoek na Kristin Linklater se benadering tot stemontwikkeling
    (Stellenbosch : University of Stellenbosch, 2008-03) Van der Merwe, Schalk Willem; Kruger, M. S.; University of Stellenbosch. Faculty of Arts and Social Sciences. Dept. of Drama.
    In a study of Kristin Linklater’s approach to voice training the concept of the natural voice and the freeing of it stands central. The natural voice according to Linklater is that voice which is naturally produced by the voice-organs without any restrictions that can inhibit it and thus have a maximum potential for the use during speech/work. The opposite to the natural voice is the unnatural voice, which can be described as the production of speech in such a manner that it is restricted or inhibited by conscious or unconscious means. Linklater’s approach focuses on the recognition of the natural voice and the freeing it from negative habits. Her freeing theory with regards to the natural voice consists of the junction of the acknowledgment of physical and psychological habits in the body with the aim of strengthening the natural voice and not only to teach new vocal techniques and habits. The process of freeing the natural voice consists of recognizing and eliminating negative speech and voice related habits. Linklater’s approach to voice training is not unique. The approaches of the other voice theoreticians such as Berry, Rodenburg, Houseman and Lessac have the same kind of approach to voice training (wich includes the concept of the natural voice). Al though some differences occur in connection to their approaches to the roots of habits and the conditioning of voice habits and the eventual freeing of the natural voice through unlearning of the habits that suppress the natural voice.