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This thesis presents the results of a study into the use of H^ꝏ-optimization for the design of feedback control laws for improving the handling qualities of a Lynx helicopter. An important improvement to the H^ꝏ-optimization procedure is the reduction in the number of iterative steps in the γ-iteration before convergence to the optimal γ. Some new algorithms are derived which significantly reduce the computation time for the γ-iteration. Both 2-block and 4-block cases are considered. Control laws are designed for precise control of pitch and roll attitude, yaw rate and heave velocity. Analysis of the raw helicopter showed the need for a stability augmentation system as the dynamic characteristics of the unaugmented helicopter do not comply with military helicopter handling qualities requirements. Results from current research on helicopter handling qualities were used as guidelines in order to define the required dynamic characteristics. A six-degree of freedom nonlinear simulation was used to analyse the helicopter dynamic time histories. A possible solution to the problem of incorporating helicopter handling qualities in the design of robust controllers is to use a two-degree of freedom controller structure. This is illustrated using both H₂ and H^ꝏ-optimization. A piloted simulation study to assess the effectiveness of advanced control laws was initiated at RAE, Bedford. The trials were carried out in the single seat cockpit flight simulator, at the Flight Research Division and represent the first ever real-time piloted simulation using a H^ꝏ-controller.

Studiens syfte är att bidra med kunskap om hur barn använder sig av det naturliga materialet i sin lek utomhus. Forskning visar att det naturliga materialet är något som är bra och utvecklande för barn men att förskollärare har minimal kunskap om detta. Frågeställningar som studien utgår från är: Vilka medierande handlingar skapas i barns utelek med naturliga material? Hur används tidigare erfarenheter i lek med naturligt material? Studien utgår från ett sociokulturellt perspektiv och resultatet analyseras med hjälp av interaktionsanalys. Observationerna genomförs på två olika förskolor i Sverige och de barn som medverkar i studien är 2-5 år. I resultatet framkommer det att barn använder sin fantasi och sina tidigare erfarenheter i lek med naturliga material utomhus. Förskollärarnas regler och tidigare erfarenheter sätter stopp för barns lek och det naturliga materialet är inte alltid deras förstahandsval vid valet av material i leken. En slutsats i studien är att barn är fantasifulla och kreativa och kan på så vis skapa lek och de omvandlar det naturliga materialet till något nytt som de är intresserade av.

This thesis systematically investigates the nano handling and measurement techniques for biological cells in culture and studies the techniques to realize innovative and multi-functional applications in biomedicine. Among them, the technique based on AFM is able to visualize and quantify the dynamics of organic cells in culture on the nano scale. Especially, the cellular shear adhesion force on the various locations of biological cells was firstly accurately measured in the research of the cell-substrate interaction in terms of biophysical perspective. The innovative findings are conductive to study the cell-cell adhesion, the cell-matrix adhesion which is related to the cell morphology structure, function, deformation ability and adhesion of cells and better understand the cellular dynamic behaviors. Herein, a new liquid-AFM probe unit and an increment PID control algorithm were implemented suitable for scanning the cell samples under the air conditions and the liquid environments. The influence between the surface of sample and the probe, and the damage of probe during the sample scanning were reduced. The proposed system is useful for the nano handling and measurement of living cells. Besides, Besides, to overcome the limitations of liquid-AFMs, the multiple optical tweezers were developed to integrate with the liquid-AFM. The technique based on laser interference is able to characterize the optical trap stiffness and the escape velocity, especially to realize the capture and sorting of multiple cells by a polarization-controlled periodic laser interference. It can trap and move hundreds of cells without physical contact, and has broad application prospects in cytology. Herein, a new experimental method integrated with the positioning analysis in the Z direction was used to improve the fluid force method for the calibration and characterize the mechanical forces exerted on optical traps and living cells. Moreover, a sensitive and highly efficient polarization-controlled three-beam interference set-up was developed for the capture and sorting of multiple cells. By controlling the polarization angles of the beams, various intensity distributions and different sizes of dots were obtained. Subsequently, we have experimentally observed multiple optical tweezers and the sorting of cells with different polarization angles, which are in accordance with the theoretical analysis.

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MSc (Med), Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 2009 / This study assessed the effect that certain logistical and methodological factors in the laboratory could have on influencing precision and accuracy of enumeration of CD4+ cells. The efficacy of a new blood stabiliser to extend the window of CD4 testing, was also evaluated. CD4+ counts were derived using the 2-colour Pan-leucogating, 4-colour TetraONE and MultiTEST/TruCount protocols on the EPICS-XL, FC-500 or FACSCalibur flow cytometers. Statistical analyses included the paired-t-test, Spearman’s correlation and Bland Altman comparisons. The results showed that the reliability of CD4+ count results was heavily dependent on how blood samples were handled prior to and after receipt into the laboratory and on how samples were processed and analysed. The factors, motion, operator pipetting and analysis skills, storage temperature, use of different protocols, different gating strategies and the use of different flow cytometers, were found to influence accurate and precise enumeration of CD4+ counts.

Video summarizing a Ph.D. dissertation for a non-specialist audience. / Upper Great Plains Transportation Institute (UGPTI) / Transportation and Logistics / Transportation and Logistics / College of Business

Lau, Sin Heng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 17). / Abstracts in English and Chinese.

Vita. / Digitized by Kansas Correctional Industries

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