1,721,390 research outputs found
Aralia racemosa: Lowlight Lush for Every Season
No full textLewis, Christopher. (2021). Aralia racemosa: Lowlight Lush for Every Season. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/225173
The effects of vibration on the performance of human operators in continuous manual control systems
No full textThe harpsichord in twentieth-century Britain
No full textThis dissertation provides an overview of the history of the harpsichord in twentieth century Britain. It takes as its starting point the history of the revival harpsichord in the early part of the century, how the instrument affected both performance of historic music and the composition of modern music and the factors that contributed to its decline. Information regarding British composers, performers, and individual works has been gathered together in a database. Analysis of this database allows the consideration of how the characteristics of the revival harpsichord shaped the use of the instrument throughout the century. More detailed case studies of the harpsichord works of three composers writing at different points in the century: Lennox Berkeley, Stephen Dodgson, and Michael Nyman are then plotted against this narrative. Conclusions will be drawn from analysis of the case studies and will consider how the harpsichord has moved away from its nostalgic associations, and how has it not
Mechanisms of the effects of vibration frequency, level and duration on continuous manual control performance
No full textThis paper describes three experiments, performed to determine the effects of vibration frequency, level and duration on a zero order, pursuit tracking task, and to discover the mechanisms responsible for these effects. The first experiment investigated the effect on tracking performance of vertical, sinusoidal vibration of the control stick in the frequency range 4 to 64 Hz. Control dynamics were either isotonic (displacement), isometric (force) or spring-centred. The second experiment investigated the effect of level of vertical, 4 Hz and 16 Hz whole-body and control vibration on performance with the isotonic and isometric controls. Experiment 3 investigated the effects of duration of continuous, vertical, whole-body vibration at 4 Hz, for durations up to 1 h, on performance with the isotonic and isometric controls. Performance measures included closed-loop transfer functions of the human operator and components of mean-square tracking error correlated with the forcing functions and vibration, and those due to operator-generated noise or remnant. The results indicated that the primary effects of vibration on the tracking task were increases in remnant and vibration-correlated error. Perceptual and motor sources are suggested for the increased remnant. The effects were largest with 4 Hz vibration and were found to be effectively constant throughout 1 h exposures to continuous 4 Hz whole-body vibration, but after relatively short periods the effect on overall tracking performance was effectively masked by large increases in response lags and suppression of coherent responses, which occurred in both static and vibration conditions as a consequence of diminished levels of arousal.</p
Predicting the effects of vibration frequency and axis, and seating conditions on the reading of numeric displays
No full textTen subjects performed a numeral reading task under five levels of sinusoidal whole-body vibralion at various frequencies in each of the three translational axes. In the z-axis the vibration frequencies were spaced at half octaves between 2-8 and 63 Hz, and in the x and y-axes at half octaves between 2-8 and 32 Hz. All of the vibration conditions were presented with two sealing conditions: hard flat seat with fixed footrest and a simulated helicopter seat with moving footrest. With both seats the effect of vibration level on reading accuracy was found to be significant at all but the highest frequencies of z-axis vibration. It was also significant for x-axis vibration with the simulated helicopter seat, but not for x-axis vibralion with the flat seat or for y-axis vibration with either seat. Results are presented in the form of equal performance contours.Measures of translational and rotational head motion were also made for each vibration axis and seat. Very little vibration was found to be transmitted to the head during x-axis vibration with the flat seat or y-axis vibration with either seat, in agreement with the small effect of vibration on reading performance in these cases. These results were combined with performance data to investigate the feasibility of predicting performance decrements directly from head motions.</p
Dealing with Juvenile Offenders in the Criminal Justice System
No full textThe treatment of juveniles within the criminal justice systems is a matter of great variety in the 11 European countries studied comparatively. The study focuses on the age of criminal responsibility, ways to divert juvenile offenders from the criminal justice system or avoid criminal justice responses to them, juvenile proceedings and special reactions and sanctions. In spite of different approaches there is a common trend towards preventing juvenile offenders from being treated by criminal courts and being sentenced to criminal sanctions
Human factors consideration in clinical applications of virtual reality
No full textVirtual reality environments have many potential applications in medicine, including surgical training, tele-operated robotic surgery, assessment and rehabilitation of behavioural and neurological disorders and diagnosis, therapy and rehabilitation of physical disabilities. Although there is much potential for the use of immersive virtual reality environments in clinical applications, there are problems which could limit their ultimate usability. Some users have experienced side-effects during and after exposure to virtual reality environments. The symptoms include ocular problems, disorientation and balance disturbances, and nausea. Susceptibility to side-effects can be affected by age, ethnicity, experience, gender and physical fitness, as well as the characteristics of the display, the virtual environment and the tasks. The characteristics of the virtual reality system have also been shown to affect the ability of users to perform tasks in a virtual environment. Many of these effects can be attributed to delays between the sampling of head and limb positions and the presentation of an appropriate image on the display. The introduction of patients to virtual reality environments, for assessment, therapy or rehabilitation, raises particular safety and ethical issues. Patients exposed to virtual reality environments for assessment and rehabilitation may have disabilities which increase their susceptibility to certain side-effects. Special precautions therefore need to be taken to ensure the safety and effectiveness of such virtual reality applications. These precautions include minimisation of possible side-effects at the design stage. Factors are identified which are likely to affect the incidence of side-effects during and after exposures, and which need to be understood in order to minimise undesirable consequences. There is also a need for the establishment of protocols for monitoring and controlling exposures of patients to virtual reality environments. Issues are identified which need to be included in such protocols.</p
Evaluating the motions of a semi-submersible platform with respect to human response
No full textThe motions of a semi-submersible drilling platform have been evaluated so as to predict the effects on the comfort and activities of the crew. The horizontal motions at the drill floor exceeded the 'average threshold of perception' defined in International Standard 6897 (ISO 6897, 1984) by more than a factor of two; they were about half of the limit for the worst 10 min in five years for 'fixed offshore structures where work of a somewhat critical nature is carried out'. Other standards predict that the vertical motion would cause vomiting due to motion sickness in less than 5% of unadapted adults within the first 8h of exposure. The calculated probability of 'motion-induced interruptions' (loss-of-balance events) caused by deck motion was negligible. Notwithstanding the above conclusions, it is considered that current standards are insufficient to predict the effects of the motions of ships and floating platforms on the activities of the crew.</p
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