130 likes | 284 Views
IE 553 Engineering of Human Work Dr. Andris Freivalds Class #20. IE 553 Engineering of Human Work Dr. Andris Freivalds Class #20. Vibration (Ch. 12). Forced = external Free = internal Average = ( ∫|x|dt/T) ½ RMS = ( ∫x 2 dt/T) ½ dB = 20 log 10 (a/a 0 ) Piezoelectric sensors
E N D
IE 553 Engineering of Human Work Dr. Andris Freivalds Class #20 IE 553
IE 553 Engineering of Human Work Dr. Andris Freivalds Class #20 IE 553
Vibration (Ch. 12) • Forced = external • Free = internal • Average = (∫|x|dt/T)½ • RMS = (∫x2dt/T)½ • dB = 20 log10 (a/a0) • Piezoelectric sensors • Accelerometers IE 553
Effects on Human - Physiological • Activates muscles • Skeletal (back) • Smooth (arterioles) • Problem in hands • HAVS - blanching • “White finger” • Raynaud’s disease IE 553
Cumulative Effect IE 553
HAVS - Attenuation IE 553
Whole-Body Limits (Vertical) IE 553
Hand-arm Limits IE 553
Worker Selection (Ch. 13)Assigning the right worker to the right job Accuracy = test’s ability to provide true answer, small deviations from target Precision = small variations about mean IE 553
Sensitivity and Specificity Sensitivity = Test’s ability to identify worker’s developing disease = a/(a+c) Specificity = Test’s ability to identify worker’s not developing disease = d/(b+d) IE 553
X-rays Anthropometry Range of motion and pain Muscle strength General fitness General awareness Lifting techniques Use of aids Training Physical Examination Back belts IE 553