Optimal work-rest schedules under prolonged vibration.
This research was conducted for the purpose of studying the performance and recovery characteristics of men when subjected to low-level, whole-body vertical sinusoidal vibration for durations of one to two hours. Several male subjects performed a vertical compensatory tracking task using a CKT display according to three work-rest schedules under both normal and vibratory environments. The vibratory environment was that of vertical sinusoidal vibration with a frequency of.5 cps and an amplitude- of 0-08 inches resulting in an acceleration intensity of approximately 0.20 g. The working period was divided into equal intervals during which performance was continuously monitored. Decrement of performance was measured using absolute error score. Results and conclusions are presented regarding performance decrement and recovery under varying work-rest schedules. Optimum work-rest schedules and implications of control tasks under a vibratory environment are discussed.
Review of the effects of translational whole-body vibration on continuous manual control performance
A review of the literature concerned with experimental studies of the effects of translational whole-body vibration on continuous manual control performance is presented. Results from studies of the effects of vibration variables (vibration frequency, magnitude, axis, random vibration and multi-axis vibration) are compared. Evidence of the influence of control system variables (physical characteristics of the control, control gain, system dynamics and display variables) is also provided. Studies of the effects of vibration duration on manual control performance are reviewed separately. A behavioural model is presented to summarize the mechanisms (including vibration breakthrough, visual impairment, neuro-muscular interference and central effects) by which whole-body vibration may interfere with the performance of continuous manual control tasks. The model emphasizes the adaptive ability of the human operator.
Timber, its nature and behaviour
Preface. Acknowledgements. Chapter 1 - Structure of Timber. Chapter 2 - Appearance of Timber in Relation to its Structure. Chapter 3 - Mass Volume Relationships. Chapter 4 - Movement in Timber. Chapter 5 - Flow in Timber. Chapter 6 - Deformation Under Load. Chapter 7 - Strength and Failure in Timber. Chapter 8 - Durability of Timber. Chapter 9 - Processing of Timber. Index.