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.
PHYSIOLOGICAL AND PATHOLOGICAL EFFECTS OF MECHANICAL VIBRATION ON ANIMALS AND MAN
Abstract : Contents: Rat studies: Metabolic and growth responses of unrestrained rats to repeated exposures of vibration, and effects of vibration on pregnant rats Dog studies: General responses of dogs to whole-body vibration; blood pressure responses to whole-body vibration in anesthetized dogs; and blood flow in arteries of vibrated animals Human studies: Human psychomotor performance during prolonged vertical vibration; oxygen consumption during human vibration exposure; respiratory frequency, tidal volume, and respiratory minute volume in human subjects exposed to vertical whole-body vibration; skin resistance (psycho-galvanic response) during whole-body vibration; body surface responses of standing male subjects subjected to vertical vibrations; occupational Raynaud's phenomena due to vibrating tools; and detection, recognition and identification of visual forms as a function of target size and whole-body vibration.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.