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It is well known that high-speed liquid jetting is one of the most powerful techniques available to cut or penetrate material. Recently, it has been conjectured that high-speed liquid jets may be beneficial in improving combustion in such applications as SCRAM jets and direct injection diesel engines. Although there are practical limitations on maximum jet velocity, a fundamental study of the characteristics of high-speed liquid fuel jets and their auto-ignition feasibility is necessary. Important benefits could be increased combustion efficiency and enhanced emission control from improved atomisation. The generation of high-speed liquid jets (water and diesel fuel) in the supersonic to hypersonic ranges by use of a vertical single stage powder gun is described. The effect of the projectile velocity and projectile mass on the jet velocity is found experimentally. Jet exit velocities from a range of different nozzle inner profiles and nozzle hardness are thoroughly examined. The characteristics and behaviour of the high-speed liquid jet and its leading bow shock wave have been studied with the aid of a shadowgraph technique. This provides a clearer picture of each stage of the generation of hypersonic liquid jets. It makes possible the study of hypersonic diesel fuel jet characteristics and their potential for auto-ignition. The fundamental processes by which a supersonic liquid jet is generated by projectile impact have been investigated. The momentum transfer from the projectile to the liquid and the shock wave reflection within the nozzle cavity are the key items of interest. A new one-dimensional analysis has been used in order to simplify this complex and difficult problem. The impact pressure obtained from the projectile was firstly derived. Then, an investigation of the intermittent pressure increase in a closed end cavity and a simple stepped, cross-sectional nozzle were carried out. The nozzle pressure and final jet velocity were estimated and compared to a previous method and to experimental results. Some interesting characteristics found in the experiments relate well to those anticipated by the analysis. The characteristics of a hypersonic diesel fuel jet and its leading edge shock wave were assessed for their potential for auto-ignition using fuel with cetane numbers from 50-100. The investigations were performed at normal ambient air and at elevated air (110 ???C) temperature. So far, there is no sign of auto-ignition that may occur because of the temperature rise of the induced shock.

The study presents a one-dimensional, transient and compressible flow models of a commercial Common Rail Injector (CRI) and a prototype of a single-fuel Hydraulically actuated Electrically controlled Unit Injector (HEUI) developed at the University of New South Wales (UNSW) in conjunction with local industry. The unique feature of the UNSW HEUI is the fact that it uses diesel fuel as the driver for pressure amplification within the unit injector. The work undertaken is part of a wider study aimed at optimization of the design of diesel injectors for dual-fuel systems to reduce green house gas emissions. The contribution of this thesis is the development of the model of the UNSW HEUI injector, which can be used to investigate possible modifications of the injector for its use in dual-fuel injection systems. The developed models include electrical, mechanical and hydraulic subsystems present in the injectors. They are based on Kirchhoff??s laws, on the mass and momentum conservation equations and on the equilibrium of forces. The models were implemented in MATLAB/SIMULINK graphical software environment, which provides a high degree of flexibility and allows simulation of both linear and nonlinear elements. The models were used to perform sensitivity analysis of both injectors. The sensitivity analysis has revealed that the temperature of the solenoid coil is one of the critical parameters affecting the timing and the quantity of the fuel injection of both injectors. Additional critical parameters were found to be the dimensions of the piston of the CRI, the stiffness of the needle spring of the HEUI and the dimensions of the intensifier of the HEUI. The models also revealed that in the case of pilot injections the speed of the solenoid is the major limiting factor of the performance. The developed models provide better understanding of the issues and limitations of the injectors. They give detailed insight into their working principles. The investigations of the models permit making quantitative analysis of the timing of the HEUI solenoid and to evaluate the proposed change of the direction of the pressure acting on the HEUI solenoid plunger.

Includes bibliographical references. / 1 v. ; / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Presented as the progression from initial investigations of the nervous system of the anaesthetised cat, through recordings in the brain of unanaesthetised monkeys, to the human neuromuscular system. / Thesis (D.Sc.)--University of Adelaide, Dept. of Physiology, 1998?

Many of the problems associated with the planning and execution of human arm trajectories are illuminated by planning and control strategies which have been developed for robotic manipulators. This comparison may provide explanations for the predominance of straight line trajectories in human reaching and pointing movements, the role of feedback during arm movement, as well as plausible compensatory mechanisms for arm dynamics.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: Timothy D. Lee. Includes bibliographical references. Also available online.

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99279

Thesis (D.Tech.-Mechanical engineering)--Cape Technikon, 1997. / Includes bibliography. Also available online.

Studies investigating human information processing have provided evidence that in some cases, movements can be prepared in advance. Although evidence for motor preparation has been shown at cortical and spinal levels, motor preparation at a subcortical level is not well described. One line of inquiry has involved the use of a startling acoustic stimulus (115-124 dB) that can act as an early trigger for pre-programmed actions in reaction time (RT) tasks. In light of this new research paradigm, the startle reflex may be used as a tool to investigate motor preparation. Here, six experiments were conducted that work towards the goals of understanding the mechanism of RT shortening due to startle, and motor preparation at a subcortical level. The first section (2 experiments) of this dissertation provides evidence that when a motor action can be prepared in advance, it is pre-programmed and stored subcortically awaiting the normal cortical “go” signal. A startle appears to activate structures directly that are involved with the voluntary response channel leading to early triggering of the pre-programmed response, and dramatically reduced RT. In the current dissertation we investigated alternative mechanisms to explain startle RT facilitation, including the stimulus intensity effect, and a fast transcortical route, with results supporting the original subcortical storage hypothesis. The second section (4 experiments) presents data which together provide insight into motor programming processes, and the circumstances under which a response is pre-programmed. For example, when the possibility of not having to make the response existed, a known response was not pre-programmed. Similarly, no pre-programming occurred when certainty existed regarding when to respond. However, while a previous experiment showed that having to make a choice between several response alternatives precluded pre-programming, this dissertation shows that if possible response alternatives are not in conflict with one another, multiple responses can be prepared in parallel. Finally, the complexity of a response such as one involving multiple sequenced sub-components may limit the ability to pre-program in a simple RT task. Taken together, these results suggest that pre-programming is dependent on the task characteristics and appears to involve implementation of strategies to increase programming efficiency.

This work aims to further the understanding of the trajectory and velocity profile of curved motion. Two competing theories, the two-thirds power law and the minimum jerk velocity profile, were tested. A set of two experiments was run that had the subjects generate curved motion. The first experiment had subjects move along a bounded oval and the second experiment had subjects move is a less constrained manner inducing a curved path. The study shows evidence for the expected effects of distance travel and allowable room for error. The evidence for the two movement profiles explaining the data is minimal.