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Methods of evaluating pulsed vibration (vibration evaluation methods 3)
578
HUMAN RESPONSE TO VIBRATION
subject seated on a standard DC-8 seat from vertical random vibrations typical of those experienced at the cockpit of commercial transports during turbulent flight. A column and wheel (un-isolated from the vibratory motions) and side-arm controller (attached to the isolated seat) were used by the subject for control inputs to a two-axis (pitch and roll) tracking task using a cathode ray tube (CRT) to simulate an aircraft flight director. Tracking error measurements in roll and pitch were made for fixed base, vibration, isolated seat and simulated total (seat and display) isolation configurations. Combination of column and wheel, side-arm controller, fixed rubber pedals (un-isolated from the vibratory motions) and foot-rest (attached to the isolated seat) were used during the tests. Results from error measurements showed that only minimal changes in control capability occurred from.the addition of active seat isolation for the two-minute test period. Subjective response indicated that the seat isolation systems provided a dramatic improvement in comfort over that afforded by the standard seat. However, large relative deflections between the subject and displays which occurred for low frequency vibration inputs made it difficult for the subject to analyze and interpret the error in term s of displacement, rate and acceleration. It is postulated that long-time duration testing will show an improvement in tracking ability relative to that of the standard seat as a result of an anticipated decrease in fatigue. Consequently, it is recommended that such a long-time duration test program be conducted to validate this assumption. Results also showed that the best combination of improved ride comfort and tracking performance can be expected from a system which has the capability of isolating the displays, seat, and controls. It is recommended that a feasibility study be made to determine if such a "total isolation system" is practical to build. Topics: Anti- Vibration Devices (Controls and Displays); Perceptual 31echanisms (Vision); Performance (h, General); Subjective Assessment; Complex Vibration (Random). B. B. Blivaiss, R. Litta-Modignani, G. Galansino and P. P. Foa 1965 Aerospace Medichle 36, 1138-1144. Endocrine and metabolic response of dogs to whole body vibration. (7 pages, 7 figures, 1 table, 45 references). . Authors" Abstract. To determine the endocrine and metabolic response of restrained dogs to whole body vibration, pentobarbital anesthetized and non-anesthetized dogs were vibrated horizontally. After vibration of anesthetized dogs at either 4 Hz, 0.4 g for 30 minutes or 2 hours, or at 10 Hz, 2.3 g for 2 hours, there was an average increase of 4.08 mcg 17-hydroxycorticosteroids (17-OH-CS) per I00 ml plasma and a significant increase in blood epinephrine but not serotonin or norepinephrine. Shaking at 4 Hz, 1.7 g for 30 minutes produced less of a change in plasma 17-OH-CS than at 0.4 g. However, shaking at 4 Hz for 6 hours led to greater increase in plasma 17-OH-CS at 1.7 g than 0.4 g. Non-anesthetized dogs shaken at 4 Hz for 30 minutes had a greater increase of plasma "I7-OH-CS than similarly shaken anesthetized dogs, thus showing a greater sensitivity of kinesthetic receptors to vibratory stimuli. Possible mechanisms for alterations in endocrine function are discussed. Topics: Non-human Subjects; Physiological Effects (Emtocrhle/Metabolic). T. Miwa and Y. Yonekawa 1971 NASA TT F-13,987 (Translation of "Shogeki Shindo no Hyokaho (Shindo no Hyokaho 3)" Acoustical Society of Japan, Journal 27, 33-39). Methods of evaluating pulsed vibration (vibration evaluation methods 3). (14 pages, 4 figures, 2 tables, 10 references) Authors" Abstract. Pulsed vibrations seen in forging and pile driving works have almost completely occupied workers on the vibration problems concerning human sensation. Results derived by Reiher and Meister are helpful for assessment of the pu.lsed vibrations. However, they have treated damped vibrations alone, although there are several other kinds
HUMAN RESPONSE TO VIBRATION
579
of pulsed vibrations such as pulsed sinusoidal and built-up vibrations. Sensation of the pulsed sinusoidal (PS) vibration of a certain constant level was matched to continuous (CS) vibration of variable level having the same frequency as the fundamental frequency of the PS vibration. Duration of PS vibration was changed between 6 and 0.007 seconds. The results of the matching experiments on the whole body and the hand for vertical or horizontal vibration are shown. The ordinate indicates VALp - VALj (dB) and the abscissa the duration of the PS vibration (t) (s). VAPp means vibration acceleration level (VAL) of the CS wave which has the same maximum amplitude and the same fundamental frequency as the PS vibration, and VALj means the VAL value of the CS vibration judged as the equal sensation with the PS vibration. These results are approximated by three lines, formulated as V A P p - VALj = 71ogioTo/t, where To is the critical time limit which was nearly 2 seconds for 2-60 Hz, 0.8 seconds for 60-200 Hz and 0.5 seconds above 200 Hz. Then, the sensation of the damped or the built-up vibration was equalized to that of the PS vibration having the same fundamental frequency and the maximum amplitude by changing the duration of the PS vibration every half period of its fundamental frequency. It was found that the damped vibration, regardless of decay processes, is equalized to one period of the PS vibration and that the built-up vibration is equalized to the PS vibration of tile duration which corresponds to its duration just when the amplitude of the built-up vibration is smaller by 1-5 dB from its maximum value. The matched duration of the PS vibration is defined as equivalent duration. Thus, the vibration greatness sensation for the damped or the built-up vibration can be estimated from the equivalent PS vibration. On the other hand, the estimated values were compared with the observed values which were determined by the sensational comparison between the damped or the built-up vibration and the CS vibration having the same fundamental frequency. Both values are in good agreement. Evaluation methods for these three kinds of pulsed vibrations were eventually established. Topics: Subjective Assessment (httensity Matchhlg); Complex Vibration (hnpulse).
E. L u k ~ and V. Ku~el 1971 hlternationaIArchiv Arbeitsmedizin 28, 239-249. Klinische und Elektromyographische Diagnostik der Sch~idigung des peripheron Nervensystems durch Lokale Vibration (Clinical and electromyographical diagnosis of damage to the peripheral nervous system by local vibrations). (11 pages, 2 tables, 35 references) English Summary. A group of 137 workers from the ore mines, mean age 44.7 years, mean exposure 13.9 years, examined on suspicion of lesions of the peripheral nervous system due to vibration, manifested besides finger lividity the following subjective complaints: acrodysesthesia, pains in the upper extremities and cervical vertebral column, hypodynamia and muscle spasms. Among the objective neurological findings were hypaesthesia (mostly in glove shape), hypo and arreflexia with acrale prevalence, increased idiomuscular irritation and positive carpal-tunnel tests. Estimation of the conduction velocity of the motor and sensitive fibres in N. ulnaris and N. medianus proved pathological values in one of the several nerves in almost half the examined persons (47-4 ~o). The clinical and EMG results were compared with X-ray of the cervical vertebral column and the elbow joints, and with the cooling test. (1) Clinical and EMG correlation indicates mostly a damage of the motor fibres of N. medianus and resembles the carpal-tunnel syndrome. (2) Damage of the N. uhlaris is usually observed simultaneously with the elbow-joint processes in which shocks and vibrations have a complex effect. (3) Combined lesion of N. ulnaris and N. mediators correlates predominantly with the positive cooling tests or with the prolonged Lewis-Prusik times.
HUMAN RESPONSE TO VIBRATION
subject seated on a standard DC-8 seat from vertical random vibrations typical of those experienced at the cockpit of commercial transports during turbulent flight. A column and wheel (un-isolated from the vibratory motions) and side-arm controller (attached to the isolated seat) were used by the subject for control inputs to a two-axis (pitch and roll) tracking task using a cathode ray tube (CRT) to simulate an aircraft flight director. Tracking error measurements in roll and pitch were made for fixed base, vibration, isolated seat and simulated total (seat and display) isolation configurations. Combination of column and wheel, side-arm controller, fixed rubber pedals (un-isolated from the vibratory motions) and foot-rest (attached to the isolated seat) were used during the tests. Results from error measurements showed that only minimal changes in control capability occurred from.the addition of active seat isolation for the two-minute test period. Subjective response indicated that the seat isolation systems provided a dramatic improvement in comfort over that afforded by the standard seat. However, large relative deflections between the subject and displays which occurred for low frequency vibration inputs made it difficult for the subject to analyze and interpret the error in term s of displacement, rate and acceleration. It is postulated that long-time duration testing will show an improvement in tracking ability relative to that of the standard seat as a result of an anticipated decrease in fatigue. Consequently, it is recommended that such a long-time duration test program be conducted to validate this assumption. Results also showed that the best combination of improved ride comfort and tracking performance can be expected from a system which has the capability of isolating the displays, seat, and controls. It is recommended that a feasibility study be made to determine if such a "total isolation system" is practical to build. Topics: Anti- Vibration Devices (Controls and Displays); Perceptual 31echanisms (Vision); Performance (h, General); Subjective Assessment; Complex Vibration (Random). B. B. Blivaiss, R. Litta-Modignani, G. Galansino and P. P. Foa 1965 Aerospace Medichle 36, 1138-1144. Endocrine and metabolic response of dogs to whole body vibration. (7 pages, 7 figures, 1 table, 45 references). . Authors" Abstract. To determine the endocrine and metabolic response of restrained dogs to whole body vibration, pentobarbital anesthetized and non-anesthetized dogs were vibrated horizontally. After vibration of anesthetized dogs at either 4 Hz, 0.4 g for 30 minutes or 2 hours, or at 10 Hz, 2.3 g for 2 hours, there was an average increase of 4.08 mcg 17-hydroxycorticosteroids (17-OH-CS) per I00 ml plasma and a significant increase in blood epinephrine but not serotonin or norepinephrine. Shaking at 4 Hz, 1.7 g for 30 minutes produced less of a change in plasma 17-OH-CS than at 0.4 g. However, shaking at 4 Hz for 6 hours led to greater increase in plasma 17-OH-CS at 1.7 g than 0.4 g. Non-anesthetized dogs shaken at 4 Hz for 30 minutes had a greater increase of plasma "I7-OH-CS than similarly shaken anesthetized dogs, thus showing a greater sensitivity of kinesthetic receptors to vibratory stimuli. Possible mechanisms for alterations in endocrine function are discussed. Topics: Non-human Subjects; Physiological Effects (Emtocrhle/Metabolic). T. Miwa and Y. Yonekawa 1971 NASA TT F-13,987 (Translation of "Shogeki Shindo no Hyokaho (Shindo no Hyokaho 3)" Acoustical Society of Japan, Journal 27, 33-39). Methods of evaluating pulsed vibration (vibration evaluation methods 3). (14 pages, 4 figures, 2 tables, 10 references) Authors" Abstract. Pulsed vibrations seen in forging and pile driving works have almost completely occupied workers on the vibration problems concerning human sensation. Results derived by Reiher and Meister are helpful for assessment of the pu.lsed vibrations. However, they have treated damped vibrations alone, although there are several other kinds
HUMAN RESPONSE TO VIBRATION
579
of pulsed vibrations such as pulsed sinusoidal and built-up vibrations. Sensation of the pulsed sinusoidal (PS) vibration of a certain constant level was matched to continuous (CS) vibration of variable level having the same frequency as the fundamental frequency of the PS vibration. Duration of PS vibration was changed between 6 and 0.007 seconds. The results of the matching experiments on the whole body and the hand for vertical or horizontal vibration are shown. The ordinate indicates VALp - VALj (dB) and the abscissa the duration of the PS vibration (t) (s). VAPp means vibration acceleration level (VAL) of the CS wave which has the same maximum amplitude and the same fundamental frequency as the PS vibration, and VALj means the VAL value of the CS vibration judged as the equal sensation with the PS vibration. These results are approximated by three lines, formulated as V A P p - VALj = 71ogioTo/t, where To is the critical time limit which was nearly 2 seconds for 2-60 Hz, 0.8 seconds for 60-200 Hz and 0.5 seconds above 200 Hz. Then, the sensation of the damped or the built-up vibration was equalized to that of the PS vibration having the same fundamental frequency and the maximum amplitude by changing the duration of the PS vibration every half period of its fundamental frequency. It was found that the damped vibration, regardless of decay processes, is equalized to one period of the PS vibration and that the built-up vibration is equalized to the PS vibration of tile duration which corresponds to its duration just when the amplitude of the built-up vibration is smaller by 1-5 dB from its maximum value. The matched duration of the PS vibration is defined as equivalent duration. Thus, the vibration greatness sensation for the damped or the built-up vibration can be estimated from the equivalent PS vibration. On the other hand, the estimated values were compared with the observed values which were determined by the sensational comparison between the damped or the built-up vibration and the CS vibration having the same fundamental frequency. Both values are in good agreement. Evaluation methods for these three kinds of pulsed vibrations were eventually established. Topics: Subjective Assessment (httensity Matchhlg); Complex Vibration (hnpulse).
E. L u k ~ and V. Ku~el 1971 hlternationaIArchiv Arbeitsmedizin 28, 239-249. Klinische und Elektromyographische Diagnostik der Sch~idigung des peripheron Nervensystems durch Lokale Vibration (Clinical and electromyographical diagnosis of damage to the peripheral nervous system by local vibrations). (11 pages, 2 tables, 35 references) English Summary. A group of 137 workers from the ore mines, mean age 44.7 years, mean exposure 13.9 years, examined on suspicion of lesions of the peripheral nervous system due to vibration, manifested besides finger lividity the following subjective complaints: acrodysesthesia, pains in the upper extremities and cervical vertebral column, hypodynamia and muscle spasms. Among the objective neurological findings were hypaesthesia (mostly in glove shape), hypo and arreflexia with acrale prevalence, increased idiomuscular irritation and positive carpal-tunnel tests. Estimation of the conduction velocity of the motor and sensitive fibres in N. ulnaris and N. medianus proved pathological values in one of the several nerves in almost half the examined persons (47-4 ~o). The clinical and EMG results were compared with X-ray of the cervical vertebral column and the elbow joints, and with the cooling test. (1) Clinical and EMG correlation indicates mostly a damage of the motor fibres of N. medianus and resembles the carpal-tunnel syndrome. (2) Damage of the N. uhlaris is usually observed simultaneously with the elbow-joint processes in which shocks and vibrations have a complex effect. (3) Combined lesion of N. ulnaris and N. mediators correlates predominantly with the positive cooling tests or with the prolonged Lewis-Prusik times.