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Sample records for hand-arm vibration exposure

  1. Hand-arm vibration exposure monitoring with wearable sensor module.

    PubMed

    Austad, Hanne O; Røed, Morten H; Liverud, Anders E; Dalgard, Steffen; Seeberg, Trine M

    2013-01-01

    Vibration exposure is a serious risk within work physiology for several work groups. Combined with cold artic climate, the risk for permanent harm is even higher. Equipment that can monitor the vibration exposure and warn the user when at risk will provide a safer work environment for these work groups. This study evaluates whether data from a wearable wireless multi-parameter sensor module can be used to estimate vibration exposure and exposure time. This work has been focused on the characterization of the response from the accelerometer in the sensor module and the optimal location of the module in the hand-arm configuration.

  2. Hand-arm vibration hazard and prevention in China.

    PubMed

    Xiao, J M; Zheng, F Y

    1996-02-01

    The status of the hand-arm vibration exposure and action for reducing vibration risk in China is outlined. The survey indicated that more than three million workers are exposed to hand-arm vibration. The vibration syndrome has been reported in sixteen provinces; over ten industries and twenty types of job. The measurement and assessment were conducted on twenty-four types of vibrating tools under normal working condition. The investigation of preventive measures is described, which includes the development of anti-vibration tools, improvement of technological processes, personal protection. A series of standards and regulations involving local vibration drawn up and published since 1980s is reviewed.

  3. Hand arm vibration syndrome among quarry workers in Vietnam.

    PubMed

    Futatsuka, Makoto; Shono, Masahiro; Sakakibara, Hisataka; Quoc Quan, Pham

    2005-03-01

    Few studies have focused on the health effects of vibrating tools on workers in the tropical area. Work conditions and health effects related to rock drill operation were studied in 102 quarry workers, including 73 rock drill operators in Vietnam. We aimed to clarify (1) risk of vibration exposure, (2) occurrence of vibration-induced white finger (VWF), and (3) characteristics of hand-arm vibration syndrome (HAVS). Total weighted r.m.s. acceleration of the Chinese -or Russian-made rock drills, was 45-55 m/s(2). According to work observation studies, daily exposure time to vibration was 160-210 min. ISO5349 predicted that this exposure level would be associated with a high risk of HAVS in workers. We found no clear evidence of VWF. There may be several reasons why no worker exhibited VWF: (1) warmer work conditions, (2) younger and less experienced workers, (3) seasonal changes in work operations, and (4) healthy worker effect. On the other hand, 5-10% of rock drill operators might be suffering from moderate HAVS which was sensori-neural type dominant. There may be some characteristic features of HAVS among quarry workers in the tropical area.

  4. Hand-arm vibration syndrome in Swedish car mechanics

    PubMed Central

    Barregard, L; Ehrenstrom, L; Marcus, K

    2003-01-01

    Aims: To assess the occurrence of hand-arm vibration syndrome (HAVS) in Swedish car mechanics, and the relation between HAVS and duration of exposure. Methods: A total of 806 mechanics answered a questionnaire on vascular and neurological symptoms, and exposure to vibrations. Mechanics with symptoms, and some mechanics without symptoms, were invited to a clinical examination, including also a timed Allen test. Vascular and neurological symptoms were classified using the Stockholm Workshop scales. The mean daily exposure (mainly using nut-runners) was 14 minutes and the mean exposure duration, 12 years. Published data have shown vibration levels in nut-runners of about 3.5 m/s2. Results: In the questionnaire, 24% reported cold induced white finger (WF), 25% persistent numbness, and 13%, reduced grip force. The clinical examination showed a prevalence of vibration induced white finger (VWF) of about 15%, mainly in stage 2, and after 20 years, of 25%. A survival analysis showed similar results. We found that the International Organisation for Standardisation (ISO) model underestimates the risk of VWF. The incidence after 1975 was 19 cases per 1000 person-years. Slow refill times in the timed Allen test were common (15% had a refill time of >20 seconds), and associated with the presence of VWF. The clinical examination revealed neurological symptoms in the hands in about 25% of subjects, mainly at stage 2. After 20 years, the prevalence was 40%. The questionnaire items on WF and numbness both showed likelihood ratios of 13. Conclusion: HAVS is common among Swedish car mechanics in spite of short daily exposure times. This underlines the need for preventive measures. PMID:12660377

  5. Validity and inter-observer reliability of subjective hand-arm vibration assessments.

    PubMed

    Coenen, Pieter; Formanoy, Margriet; Douwes, Marjolein; Bosch, Tim; de Kraker, Heleen

    2014-07-01

    Exposure to mechanical vibrations at work (e.g., due to handling powered tools) is a potential occupational risk as it may cause upper extremity complaints. However, reliable and valid assessment methods for vibration exposure at work are lacking. Measuring hand-arm vibration objectively is often difficult and expensive, while often used information provided by manufacturers lacks detail. Therefore, a subjective hand-arm vibration assessment method was tested on validity and inter-observer reliability. In an experimental protocol, sixteen tasks handling powered tools were executed by two workers. Hand-arm vibration was assessed subjectively by 16 observers according to the proposed subjective assessment method. As a gold standard reference, hand-arm vibration was measured objectively using a vibration measurement device. Weighted κ's were calculated to assess validity, intra-class-correlation coefficients (ICCs) were calculated to assess inter-observer reliability. Inter-observer reliability of the subjective assessments depicting the agreement among observers can be expressed by an ICC of 0.708 (0.511-0.873). The validity of the subjective assessments as compared to the gold-standard reference can be expressed by a weighted κ of 0.535 (0.285-0.785). Besides, the percentage of exact agreement of the subjective assessment compared to the objective measurement was relatively low (i.e., 52% of all tasks). This study shows that subjectively assessed hand-arm vibrations are fairly reliable among observers and moderately valid. This assessment method is a first attempt to use subjective risk assessments of hand-arm vibration. Although, this assessment method can benefit from some future improvement, it can be of use in future studies and in field-based ergonomic assessments.

  6. Vascular hand-arm vibration syndrome--magnetic resonance angiography.

    PubMed

    Poole, C J M; Cleveland, T J

    2016-01-01

    The diagnosis of vascular hand-arm vibration syndrome (HAVS) requires consistent symptoms, photographic evidence of digital blanching and sufficient exposure to hand-transmitted vibration (HTV; A(8) > 2.5 m/s2). There is no reliable quantitative investigation for distinguishing HAVS from other causes of Raynaud's phenomenon and from normal individuals. Hypothenar and thenar hammer syndromes produce similar symptoms to HAVS but are difficult to diagnose clinically and may be confused with HAVS. Magnetic resonance angiography (MRA) is a safe and minimally invasive method of visualizing blood vessels. Three cases of vascular HAVS are described in which MRA revealed occlusions of the ulnar, radial and superficial palmar arteries. It is proposed that HTV was the cause of these occlusions, rather than blows to the hand unrelated to vibration, the assumed mechanism for the hammer syndromes. All three cases were advised not to expose their hands to HTV despite one of them being at Stockholm vascular stage 2 (early). MRA should be the investigation of choice for stage 2 vascular HAVS or vascular HAVS with unusual features or for a suspected hammer syndrome. The technique is however technically challenging and best done in specialist centres in collaboration with an occupational physician familiar with the examination of HAVS cases. Staging for HAVS should be developed to include anatomical arterial abnormalities as well as symptoms and signs of blanching. Workers with only one artery supplying a hand, or with only one palmar arch, may be at increased risk of progression and therefore should not be exposed to HTV irrespective of their Stockholm stage.

  7. Reduction of the vibration of the hand-arm system by optimization of rotary hammer drills.

    PubMed

    Weinert, K; Gillmeister, F

    1996-02-01

    When operating a hand-held vibrating power tool, for example impact drills and rotary hammers, high vibration loads are introduced into the hand-arm system of the operator. In the long run these mechanical vibrations can lead to health problems of the hand-arm system. Hammer drilling tools for treatment of mineral materials are offered with many different designs of the cutting edge in the diameter range between 16 mm and 50 mm. In this research project the influences of the cutting edge design of drilling tools on the vibration characteristics of rotary hammers are investigated. The vibration exposure of the hand-arm system due to the tool and the volume of chip production are regarded. The gauge being a combination of the weighted acceleration and the drilling capacity. Based on the current spectrum of drillings tools neutral test have been developed to examine geometrical parameters. Both sets of drilling tools have been subjected to the same test programme. The analysis of the results led to the definition of the characteristics of an optimized rotary hammer drilling tool. Lists of criterions have been developed for the different groups of tools. Using these it is possible to create drilling tools optimized for vibration exposure. This was demonstrated by prototype drilling tools. The comparison of the results showed, that the averaged volume of chip production could be significantly improved by modifying the design of the drilling tools retaining the weighted acceleration. The comparison also showed that the total vibration severity parameter decreased.

  8. An examination of the vibration transmissibility of the hand-arm system in three orthogonal directions

    PubMed Central

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.; Wu, John Z.

    2015-01-01

    The objective of this study is to enhance the understanding of the vibration transmission in the hand-arm system in three orthogonal directions (X, Y, and Z). For the first time, the transmitted vibrations distributed on the entire hand-arm system exposed in the three orthogonal directions via a 3-D vibration test system were measured using a 3-D laser vibrometer. Seven adult male subjects participated in the experiment. This study confirms that the vibration transmissibility generally decreased with the increase in distance from the hand and it varied with the vibration direction. Specifically, to the upper arm and shoulder, only moderate vibration transmission was measured in the test frequency range (16 to 500 Hz), and virtually no transmission was measured in the frequency range higher than 50 Hz. The resonance vibration on the forearm was primarily in the range of 16–30 Hz with the peak amplitude of approximately 1.5 times of the input vibration amplitude. The major resonance on the dorsal surfaces of the hand and wrist occurred at around 30–40 Hz and, in the Y direction, with peak amplitude of more than 2.5 times of the input amplitude. At higher than 50 Hz, vibration transmission was effectively limited to the hand and fingers. A major finger resonance was observed at around 100 Hz in the X and Y directions and around 200 Hz in the Z direction. In the fingers, the resonance magnitude in the Z direction was generally the lowest, and the resonance magnitude in the Y direction was generally the highest with the resonance amplitude of 3 times the input vibration, which was similar to the transmissibility at the wrist and hand dorsum. The implications of the results are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration could result in hand-arm vibration syndrome. While the syndrome's precise mechanisms remain unclear, the characterization of the vibration transmissibility of the system in the three orthogonal

  9. Transmission of hand-arm vibration to the head.

    PubMed

    Sakakibara, H; Kondo, T; Miyao, M; Yamada, S; Nakagawa, T; Kobayashi, F; Ono, Y

    1986-08-01

    A "tooth impression" was devised to measure head vibration. The vertical head vibration of four subjects was measured with the tooth impression during exposure of the hand to vertical sinusoidal vibration at acceleration levels of 3.15, 10.0, and 31.5 m/s2 root mean square in the range of 8-200 Hz. While in a standing position, the subjects pulled the vibrating handle upward at a force of 5 kg with the elbow joint stretched during the tests. The measurement was repeated twice. The difference between the two measurements was within 3 dB, a level which suggests that this method has good reproducibility. The vibration transmitted to the head was the greatest in the range of 12.5-16 Hz, and the attenuation was about 20 dB. Head vibration decreased by approximately 15 dB per octave at frequencies above 20 Hz as the frequency increased. When the excitation level was increased by 10 dB, the head vibration increased by about 8 dB.

  10. Combined effects of noise and hand-arm vibration on auditory organ and peripheral circulation

    NASA Astrophysics Data System (ADS)

    Miyakita, T.; Miura, H.; Futatsuka, M.

    1991-12-01

    This paper first presents an overview of an epidemiological study on noise-induced hearing loss (NIHL) in relation to vibration-induced white finger (VWF). Secondly, the results obtained in a model experiment with a chain-saw under laboratory conditions are discussed from the viewpoints of elucidating the etiological mechanisms of VWF and NIHL. In the epidemiological study, in which 499 chain-saw workers were examined, chain-saw workers with VWF showed a significantly greater hearing loss at high frequencies than those without VWF. Next, an experimental study was designed to determine whether a combination of noise and vibration produced more pronounced changes in temporary shifts of finger skin temperature and temporary threshold shift (TTS) of hearing than those resulting from exposure to either stress alone. The results suggested that noise might play a part in inducing the constriction of the peripheral vessels seen with local exposure to vibration, and that hand-arm vibration may produce an additive effect on the noise-induced TTS. Furthermore, finger skin temperature and finger blood flow were measured simultaneously as indicators of peripheral circulatory movement for five healthy subjects. The relation between the synergistic action of noise and vibration and the participation of the sympathetic nervous system are also discussed.

  11. An interpretative phenomenological analysis of the psychological ramifications of hand-arm vibration syndrome.

    PubMed

    Ayers, Beverley; Forshaw, Mark

    2010-05-01

    With a substantial number of individuals diagnosed with Hand-Arm Vibration Syndrome (HAVS) and the preponderance of research focused on the medical and paramedical issues, the psychological and mental health sequelae of HAVS are largely neglected within the published literature. A series of focus groups and interviews were conducted involving nine people who had been diagnosed with HAVS. Transcripts of these interviews were analysed using Interpretative Phenomenological Analysis. Four key themes were identified within the discourse of individuals affected by HAVS: machismo; coping; psychological impacts; and the development of support services for HAVS. Clinical implications are briefly discussed.

  12. Diagnostic value of finger thermometry and photoplethysmography in the assessment of hand-arm vibration syndrome.

    PubMed

    Bogadi-Sare, A; Zavalić, M

    1994-01-01

    Digital photoplethysmography and skin thermometry are both measures of circulation in the skin of the fingers. These methods and a cold provocation test were performed on 29 chain-saw workers grouped in stages 0, 1, 2, or 3 according to the Stockholm Workshop scale of hand-arm vibration syndrome, and on 16 controls. The reduction of photoplethysmographic amplitude after the cold test reflects the degree of vasoconstriction, and the recovery rate demonstrates passive vasodilatative capacity. Both tests were found to distinguish all vibration--exposed subjects, including those without clinically manifest vibration-induced white fingers, from the controls. With a 75% reduction in photoplethysmographic amplitude as a discriminating threshold, the sensitivity for the detection of Raynaud's phenomenon was 62% and the specificity, 87%. The discriminating threshold of 90% for recovery rate yielded a sensitivity of 69% and a specificity of 72%.

  13. Transcriptional Pathways Altered in Response to Vibration in a Model of Hand-Arm Vibration Syndrome

    PubMed Central

    Waugh, Stacey; Kashon, Michael L.; Li, Shengqiao; Miller, Gerome R.; Johnson, Claud; Krajnak, Kristine

    2016-01-01

    Objective The aim of this study was to use an established model of vibration-induced injury to assess frequency-dependent changes in transcript expression in skin, artery, and nerve tissues. Methods Transcript expression in tissues from control and vibration-exposed rats (4 h/day for 10 days at 62.5, 125, or 250 Hz; 49 m/s2, rms) was measured. Transcripts affected by vibration were used in bioinformatics analyses to identify molecular- and disease-related pathways associated with exposure to vibration. Results Analyses revealed that cancer-related pathways showed frequency-dependent changes in activation or inhibition. Most notably, the breast-related cancer-1 pathway was affected. Other pathways associated with breast cancer type 1 susceptibility protein related signaling, or associated with cancer and cell cycle/cell survivability were also affected. Conclusion Occupational exposure to vibration may result in DNA damage and alterations in cell signaling pathways that have significant effects on cellular division. PMID:27058473

  14. Vibration transmissibility characteristics of the human hand-arm system under different postures, hand forces and excitation levels

    NASA Astrophysics Data System (ADS)

    Adewusi, S. A.; Rakheja, S.; Marcotte, P.; Boutin, J.

    2010-07-01

    Biodynamic responses of the hand-arm system have been mostly characterized in terms of driving-point force-motion relationships, which have also served as the primary basis for developing the mechanical-equivalent models. The knowledge of localized vibration responses of the hand-arm segments could help derive more effective biodynamic models. In this study, the transmission of z h-axis handle vibration to the wrist, elbow and the shoulder of the human hand and arm are characterized in the laboratory for the bent-arm and extended arm postures. The experiments involved six subjects grasping a handle subject to two different magnitudes of broad-band random vibration, and nine different combinations of hand grip and push forces. The vibration transmissibility data were acquired in the z h- and y h-axis at the wrist and shoulder, and along all the three axes around the elbow joint. The results show that the human hand-arm system in an extended arm posture amplifies the vibration transmitted to the upper-arm and the whole-body at frequencies below 25 Hz, but attenuates the vibration above 25 Hz more effectively than the bent-arm posture, except at the shoulder. The magnitudes of transmitted vibration under an extended arm posture along the y h-axis were observed to be nearly twice those for the bent-arm posture in the low frequency region. The results further showed that variations in the grip force mostly affect vibration transmissibility and characteristic frequencies of the forearm, while changes in the push force influenced the dynamic characteristics of the entire hand-arm system. The magnitudes of transmitted vibration in the vicinity of the characteristic frequencies were influenced by the handle vibration magnitude.

  15. Cross sectional study of a workforce exposed to hand-arm vibration: with objective tests and the Stockholm workshop scales

    PubMed Central

    McGeoch, K.; Gilmour, W

    2000-01-01

    component while years of tool use and trade were the variables most associated with vascular damage. (3) The prevalence of neurological symptoms (62%) was greater than the prevalence of vascular symptoms (33%). (4) Dressers and welders have shorter latent periods than platers and fitters.


Keywords: hand-arm vibration syndrome; neurological objective tests PMID:10711267

  16. Assessing the influence of antivibration glove on digital vascular responses to acute hand-arm vibration.

    PubMed

    Mahbub, Md H; Yokoyama, Kenjiro; Laskar, Md S; Inoue, Masaiwa; Takahashi, Yukio; Yamamoto, Shinji; Harada, Noriaki

    2007-05-01

    This study was designed to assess the influence of an antivibration glove on digital vascular responses in healthy subjects exposed to short-term grasping of a vibrating handle. To measure finger blood flow (FBF) and finger skin temperature (FST) once at the end of every min, a blood flowmeter sensor was attached to the dorsum and a thermistor sensor was attached to the medial surface of the subject's middle phalanx of the third finger of the right hand. After 5 min of baseline measurements without or with an antivibration glove meeting ISO standard 10819, worn on the right hand, subjects gripped a vibrating handle with the same hand for a period of 5 min. Vibration was generated at two frequencies of 31.5 Hz and 250 Hz with a frequency weighted rms acceleration of 5.5 m/s(2). FBF and FST continued to be recorded for a further 5 min after release of the vibrating handle. Statistical analysis showed no significant change after vibration exposure in either FST or FBF at 250 Hz, compared to baseline (control) measurements while using the antivibration glove. At 31.5 Hz, FBF data exhibited a significant difference between before and after grasping of vibrating handle, which was less under the condition of wearing the antivibration glove than under the condition of bare hand. The results provide evidence that the antivibration glove considerably influenced finger vascular changes in healthy subjects induced by vibration exposure, especially against high frequency vibration. Further studies are required to assess finger vascular responses to hand-transmitted vibration with antivibration gloves of different manufacturers.

  17. How likely is it that Stockholm stage 1 of the hand arm vibration syndrome will progress to stages 2 and 3?

    PubMed

    Lawson, I J; McGeoch, K L

    1999-08-01

    The progression of symptoms in the hand arm vibration syndrome (HAVS) is dependent on the interaction of individual and workplace factors. Workplace factors include type, magnitude and intermittency of exposure to hand transmitted vibration (HTV), anti-vibration tool design and workpiece characteristics. Individual susceptibility and constitutional factors are poorly understood and the reliance on anamnesis for diagnosis can lead to recall bias, inaccurate classification and an unreliable assessment of the stage of deterioration. This may be overcome by the adoption of multiple standardized testing. The introduction of a policy covering identification, risk assessment, health surveillance and reasonably practicable control measures will have the most significant impact on the incidence of new cases and deterioration in established cases. PMID:10628049

  18. Hand-arm vibration syndrome among travertine workers: a follow up study.

    PubMed

    Bovenzi, M; Franzinelli, A; Scattoni, L; Vannuccini, L

    1994-06-01

    In a six year follow up study of the handarm vibration syndrome, 62 stoneworkers operating hand held vibrating tools in 10 travertine quarries and mills were first investigated in 1985 and then in 1991. The frequency weighted acceleration of vibration from the rock drills and stone hammers used by the travertine workers exceeded 20 m/s2, indicating a hazardous work activity according to the proposal of the EC directive for physical agents. A clinical examination and a cold provocation test were repeated with the same procedures as those adopted at the time of the first survey. The stoneworkers were divided into groups according to current work state: active stoneworkers who continued to use powered tools during the follow up (n = 21, median exposure time 22 years), and ex-stoneworkers with retirement vibration free intervals of three years (n = 22, median exposure time 27.5 years) and of six years (n = 19, median exposure time 20 years). In the group of active stoneworkers, a 38% onset a new cases of vibration-induced white finger (VWF) was found during the follow up (p < 0.01). Among the retired stoneworkers affected with VWF (n = 24), one recovered from VWF, one showed improvement, 20 remained stationary, and two deteriorated. The ex-stoneworkers experienced no significant change in sensorineural disturbances and a decrease in musculoskeletal symptoms of the upper limbs. At the cold provocation test, the currently active stoneworkers with VWF showed, on a group basis, a delayed finger rewarming time between the two examinations (p = 0.002). An abnormal response to cold provocation persisted in the fingers of the ex-stoneworkers with VWF, even in those reporting subjective improvement. These findings indicate a tendency towards the irreversibility of sensorineural and VWF symptoms in a group of ex-stoneworkers with prolonged exposure to high vibration levels in the past. The increased occurrence of VWF in the active stone workers after a few extra years of

  19. Hand-arm vibration in the aetiology of hearing loss in lumberjacks.

    PubMed

    Pyykkö, I; Starck, J; Färkkilä, M; Hoikkala, M; Korhonen, O; Nurminen, M

    1981-08-01

    A longitudinal study of hearing loss was conducted among a group of lumberjacks in the years 1972 and 1974--8. The number of subjects increased from 72 in 1972 to 203 in 1978. They were classified according to (1) a history of vibration-induced white finger (VWF), (2) age, (3) duration of exposure, an (4) duration of ear muff usage. The hearing level at 4000 Hz was used to indicate the noise-induced permanent threshold shift (NIPTS). The lumberjacks were exposed, at their present pace of work, to noise, Leq values 96-103 dB(A), and to the vibration of a chain saw (linear acceleration 30-70 ms-2). The chain saws of the early 1960s were more hazardous, with the average noise level of 111 dB(A) and a variation acceleration of 60-180 ms-2. When classified on the basis of age, the lumberjacks with VWF had about a 10 dB greater NIPTS than subjects without VWF. NIPTS increased with the duration of exposure to chain saw noise, but with equal noise exposure the NIPTS was about 10 dB greater in lumberjacks with VWF than without VWF. With the same duration of ear protection the lumberjacks with VWF consistently had about a 10 dB greater NIPTS than those without VWF. The differences in NIPTS were statistically significant. The possible reason for more advanced NIPTS in subjects with VWF is that vibration might operate in both of these disorders through a common mechanism--that is, producing a vasoconstriction in both cochlear and digital blood vessels as a result of sympathetic nervous system activity.

  20. Hand-arm vibration in the aetiology of hearing loss in lumberjacks.

    PubMed Central

    Pyykkö, I; Starck, J; Färkkilä, M; Hoikkala, M; Korhonen, O; Nurminen, M

    1981-01-01

    A longitudinal study of hearing loss was conducted among a group of lumberjacks in the years 1972 and 1974--8. The number of subjects increased from 72 in 1972 to 203 in 1978. They were classified according to (1) a history of vibration-induced white finger (VWF), (2) age, (3) duration of exposure, an (4) duration of ear muff usage. The hearing level at 4000 Hz was used to indicate the noise-induced permanent threshold shift (NIPTS). The lumberjacks were exposed, at their present pace of work, to noise, Leq values 96-103 dB(A), and to the vibration of a chain saw (linear acceleration 30-70 ms-2). The chain saws of the early 1960s were more hazardous, with the average noise level of 111 dB(A) and a variation acceleration of 60-180 ms-2. When classified on the basis of age, the lumberjacks with VWF had about a 10 dB greater NIPTS than subjects without VWF. NIPTS increased with the duration of exposure to chain saw noise, but with equal noise exposure the NIPTS was about 10 dB greater in lumberjacks with VWF than without VWF. With the same duration of ear protection the lumberjacks with VWF consistently had about a 10 dB greater NIPTS than those without VWF. The differences in NIPTS were statistically significant. The possible reason for more advanced NIPTS in subjects with VWF is that vibration might operate in both of these disorders through a common mechanism--that is, producing a vasoconstriction in both cochlear and digital blood vessels as a result of sympathetic nervous system activity. PMID:7272242

  1. Hand-arm vibration, noise, temperature and static load--an experimental study of peripheral circulation while operating chain-saws.

    PubMed

    Miyakita, T; Miura, H; Futatsuka, M

    1990-01-01

    From the viewpoint of elucidating the etiological mechanism of vibration-induced white finger (VWF), a model experiment was designed using a chain-saw under laboratory conditions. Finger skin temperature and finger blood flow were measured simultaneously as indicators of peripheral circulatory movement, using a thermister and an apparatus for measuring tissue blood flow based on the thermal diffusion method. In the first project (Experiment A), five healthy subjects operated a chain-saw at a high working speed with-out actually cutting anything. In the second project (Experiment B), seven healthy subjects were exposed to three different kinds of experiments with combinations of hand-arm vibration, noise and tool weight at about 15 degrees C room temperature. In the third project (Experiment C), the effects of tool weight and grip force were examined. In the fourth project (Experiment D), patients suffering from vibration disease were exposed to hand-arm vibration and the noise of a chain-saw for 2 minutes. In experiment A, the mean value of the normalized finger skin temperature decreased gradually with cyclic changes corresponding to each exposure and break period. Changes in finger blood flow had almost the same pattern as the changes of skin temperature, but the recovery of blood flow during a 30 sec break period was notable and a slight elevation of the base line was observed. In experiment B, the mean value for the normalized finger skin temperature decreased much more when the subjects operated a chain-saw at a high working speed than when they operated the chain-saw with the noise isolated by double hearing protection. On the other hand, the results obtained in experiment C indicated that the effect of tool weight should be considered as an important factor for investigating the acute changes in peripheral circulation. In experiment D, some patients showed an unusual pattern in the change of blood flow during a post exposure period which was not seen in

  2. Research into hand-arm vibration syndrome and its prevention in Japan.

    PubMed

    Yamada, S; Sakakibara, H

    1994-05-01

    Research on vibration syndrome in Japan began in the 1930s with studies of the disorder among railway, mining and shipyard workers. In 1947, the Ministry of Labor decided vibration syndrome among operators of rock drills and riveters etc. was an occupational disease. Industrial developments in the 1950s and 1960s promoted the survey of vibration syndrome in mining, stone quarrying and forestry. The Ministry of Labor (1965) and the National Personnel Agency (1966) legally recognized vibration syndrome among chain saw operators as an occupational disease. Guidelines for prevention and early therapy were issued in the 1970s and 80s. From the late 1970s into the 1980s, research focused on the clinical picture, diagnostic methods and therapy. In pathophysiology, advances were made in research into the autonomic nervous system during the 1980s. The 1970s and 80s saw a steady reduction in risk from technological change and working conditions, and advances in medical care, education and meteorological forecasting. A comprehensive prevention system established in the 1980s in the Japanese forest industry involved: 1) work restrictions, 2) an improved health care system, 3) advances in the design of vibrating tools, handle-warming devices, and 4) improved worker education. This comprehensive preventive system was legally introduced into other industries, resulting in a rapid decrease in the incidence of vibration syndrome in Japan. PMID:7708109

  3. Research into hand-arm vibration syndrome and its prevention in Japan.

    PubMed

    Yamada, S; Sakakibara, H

    1994-05-01

    Research on vibration syndrome in Japan began in the 1930s with studies of the disorder among railway, mining and shipyard workers. In 1947, the Ministry of Labor decided vibration syndrome among operators of rock drills and riveters etc. was an occupational disease. Industrial developments in the 1950s and 1960s promoted the survey of vibration syndrome in mining, stone quarrying and forestry. The Ministry of Labor (1965) and the National Personnel Agency (1966) legally recognized vibration syndrome among chain saw operators as an occupational disease. Guidelines for prevention and early therapy were issued in the 1970s and 80s. From the late 1970s into the 1980s, research focused on the clinical picture, diagnostic methods and therapy. In pathophysiology, advances were made in research into the autonomic nervous system during the 1980s. The 1970s and 80s saw a steady reduction in risk from technological change and working conditions, and advances in medical care, education and meteorological forecasting. A comprehensive prevention system established in the 1980s in the Japanese forest industry involved: 1) work restrictions, 2) an improved health care system, 3) advances in the design of vibrating tools, handle-warming devices, and 4) improved worker education. This comprehensive preventive system was legally introduced into other industries, resulting in a rapid decrease in the incidence of vibration syndrome in Japan.

  4. Aesthesiometric threshold changes over the course of a workshift in miners exposed to hand-arm vibration.

    PubMed

    Haines, T; Chong, J; Verrall, A B; Julian, J; Bernholz, C; Spears, R; Muir, D C

    1988-02-01

    The objective of this study was to investigate whether aesthesiometric threshold changes occur over the course of a workshift in vibration exposed hard rock miners relative to workers unexposed to vibration during the shift. The subjects were 99 miners and 40 smelter workers; four subjects declined to participate and nine were excluded from the analysis because of apparent failure to comprehend the testing procedure. Two point discrimination and depth sense aesthesiometry were conducted at the beginning and at the end of the workshift in all digits of both hands excluding the thumbs. In addition to the use of a vibrating tool during the shift, age, digital temperature, signs of arm injury, presence of fingertip callus, and handedness were documented. In the analysis the difference between postshift and preshift readings was studied in relation to these variables, particularly exposure to the jackleg drill during the shift. With the exception of exposure of the jackleg drill, no associations were observed between these variables and change over the workshift in aesthesiometric results, on both unadjusted comparison of means and backward elimination regression analysis. A statistically significant association, however, was found between the use of a jackleg drill and change in two point discrimination and in depth sense aesthesiometric results over the course of the shift, for the right hand. Evidence of the occurrence of a learning effect, particularly for two point discrimination aesthesiometry, was observed. The occurrence of an effect in the right, but not the left, hand reflects dominant handedness and relatively greater vibration exposure in the right hand in our subjects. This study supports the incorporation of an exposure free interval before aesthesiometric testing of vibration exposed workers.

  5. Spatial resonance in a small artery excited by vibration input as a possible mechanism to cause hand-arm vascular disorders

    NASA Astrophysics Data System (ADS)

    Pattnaik, Shrikant; Banerjee, Rupak; Kim, Jay

    2012-04-01

    Hand-arm vibration syndrome (HAVS) is collectively a vasospastic and neurodegenerative occupational disease. One of the major symptoms of HAVS is vibration white finger (VWF) caused by exaggerated vasoconstriction of the arteries and skin arterioles. While VWF is a very painful and costly occupational illness, its pathology has not been well understood. In this study a small artery is modeled as a fluid filled elastic tube whose diameter changes along the axial direction. Equations of motion are developed by considering interactions between the fluid, artery wall and soft-tissue bed. It is shown that the resulting wave equation is the same as that of the basilar membrane in the cochlea of mammals. Therefore, the artery system shows a spatial resonance as in the basilar membrane, which responds with the highest amplitude at the location determined by the vibration frequency. This implies that a long-term use of one type of tool will induce high-level stresses at a few identical locations of the artery that correspond to the major frequency components of the tool. Hardening and deterioration of the artery at these locations may be a possible cause of VWF.

  6. Vascular surgical society of great britain and ireland: analysis of cold provocation thermography in the objective diagnosis of the hand-arm vibration syndrome

    PubMed

    Coughlin; Chetter; Kent; Kester

    1999-05-01

    BACKGROUND: The hand-arm vibration syndrome (HAVS) is the commonest prescribed disease in the UK. Presently the diagnosis is subjective and the need for an objective investigation to support the diagnosis has been highlighted. This study analyses the potential of cold provocation thermography (CPT) to fulfil this role. METHODS: CPT was performed in ten controls (five men, five women; median age 35 (range 24-78) years) and 21 patients with HAVS (20 men, one woman; median age 45 (range 29-81) years). With an infrared camera, a precooling (PC) image was taken and then, following hand cooling in water at a temperature of 5 degrees C for 1 min, further rewarming images were taken every minute for 10 min. RESULTS: Patient finger tip temperatures were significantly cooler than control temperatures at all time points (P < 0.01, Student's t test). The following Table shows the sensitivity, specificity and PPV of CPT. CONCLUSION: CPT provides strong objective evidence to support the clinical diagnosis of HAVS. PMID:10361321

  7. Evaluating worker vibration exposures using self-reported and direct observation estimates of exposure duration.

    PubMed

    McCallig, Margaret; Paddan, Gurmail; Van Lente, Eric; Moore, Ken; Coggins, Marie

    2010-12-01

    The objective of this study was to compare objective and subjective methods of collecting exposure time data for hand arm vibration (HAV) and whole-body vibration (WBV), and to evaluate the impact of inaccurate exposure times' on the calculation of the average vibration exposure over an 8 h working day A(8). The study was carried out in the engineering services and maintenance departments of a construction and property management company. Worker exposure time data was collected using three methods, questionnaire surveys, daily worker interviews and 8 h direct workplace observations. Vibration magnitudes (m/s(2)) were measured for a range of hand tools and vehicles, and daily vibration exposure estimates A(8) were calculated using exposure times observed, reported in interview and self reported in the questionnaire. Results from the study showed that self-reported exposure time estimates from the questionnaire survey were a factor of 9.0 (median value) times greater for HAV and a factor of 6.0 (median value) times greater for WBV when compared with direct observation estimates. Exposure times reported in interview were higher, than those observed, but more reliable than those self reported in the questionnaire; a factor of 2.1 (median value) times greater for HAV and a factor of 1.4 (median value) times greater for WBV. A(8) values calculated using questionnaire exposure times were up to 66% and 75% greater for sources of HAV and WBV respectively when compared to A(8) values calculated using observed exposure times. For the purposes of carrying out a reliable risk assessment, results from this study indicate that direct measurements of worker exposure time are not recommended over questionnaires especially where work is highly variable for example in construction and property management. Worker interviews or direct workplace observation methods were found to be reliable alternative methods for collecting exposure time.

  8. Cochlear Damages Caused by Vibration Exposure

    PubMed Central

    Moussavi Najarkola, Seyyed Ali; Khavanin, Ali; Mirzaei, Ramazan; Salehnia, Mojdeh; Muhammadnejad, Ahad

    2013-01-01

    Background Many industrial devices have an excessive vibration which can affect human body systems. The effect of vibration on cochlear histology has been as a debatable problem in occupational health and medicine. Objectives Due to limitation present in human studies, the research was conducted to survey the influence of vibration on cochlear histology in an animal model. Materials and Methods Twelve albino rabbits were experimented as: Vibration group (n = 6; exposed to 1.0 m.s-2 r.m.s vertical whole-body vibration at 4 - 8 Hz for 8 hours per day during 5 consecutive days) versus Control group (n = 6; the same rabbits without vibration exposure). After finishing the exposure scenario, all rabbits were killed by CO2 inhalation; their cochleae were extracted and fixed in 10% formaldehyde for 48 hours, decalcified by 10% nitric acid for 24 hours. Specimens were dehydrated, embedded, sectioned 5 µm thick and stained with Hematoxylin and Eosin for light microscopy observations. Results Severely hydropic degenerated and vacuolated inner hair cells (IHCs) were observed in vibration group compared to the control group. Inter and intracellular edema was appeared in supporting cells (SC). Nuclei of outer hair cells (OHCs) seemed to be pyknotic. Slightly thickened basilar membrane (BM) was probably implied to inter cellular edematous. Tectorial Membrane (TM) was not affected pathologically. Conclusions Whole-body vibration could cause cochlear damages in male rabbits, though vibration-induced auditory functional effects might be resulted as subsequent outcome of prolonged high level vibration exposures. PMID:24616783

  9. Anti-vibration gloves?

    PubMed

    Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

    2015-03-01

    For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered.

  10. An examination of the handheld adapter approach for measuring hand-transmitted vibration exposure

    PubMed Central

    Xu, Xueyan S.; Dong, Ren G.; Welcome, Daniel E.; Warren, Christopher; McDowell, Thomas W.

    2015-01-01

    The use of a handheld adapter equipped with a tri-axial accelerometer is the most convenient and efficient approach for measuring vibration exposure at the hand-tool interface, especially when the adapter is incorporated into a miniature handheld or wrist-strapped dosimeter. To help optimize the adapter approach, the specific aims of this study are to identify and understand the major sources and mechanisms of measurement errors and uncertainties associated with using these adapters, and to explore their improvements. Five representative adapter models were selected and used in the experiment. Five human subjects served as operators in the experiment on a hand-arm vibration test system. The results of this study confirm that many of the handheld adapters can produce substantial overestimations of vibration exposure, and measurement errors can significantly vary with tool, adapter model, mounting position, mounting orientation, and subject. Major problems with this approach include unavoidable influence of the hand dynamic motion on the adapter, unstable attachment, insufficient attachment contact force, and inappropriate adapter structure. However, the results of this study also suggest that measurement errors can be substantially reduced if the design and use of an adapter can be systematically optimized toward minimizing the combined effects of the identified factors. Some potential methods for improving the design and use of the adapters are also proposed and discussed. PMID:26744580

  11. Raynaud's phenomenon among men and women with noise-induced hearing loss in relation to vibration exposure.

    PubMed

    Pettersson, Hans; Burström, Lage; Nilsson, Tohr

    2014-01-01

    Raynaud's phenomenon is characterized by constriction in blood supply to the fingers causing finger blanching, of white fingers (WF) and is triggered by cold. Earlier studies found that workers using vibrating hand-held tools and who had vibration-induced white fingers (VWF) had an increased risk for hearing loss compared with workers without VWF. This study examined the occurrence of Raynaud's phenomenon among men and women with noise-induced hearing loss in relation to vibration exposure. All 342 participants had a confirmed noise-induced hearing loss medico legally accepted as work-related by AFA Insurance. Each subject answered a questionnaire concerning their health status and the kinds of exposures they had at the time when their hearing loss was first discovered. The questionnaire covered types of exposures, discomforts in the hands or fingers, diseases and medications affecting the blood circulation, the use of alcohol and tobacco and for women, the use of hormones and whether they had been pregnant. The participation rate was 41% (n = 133) with 38% (n = 94) for men and 50% (n = 39) for women. 84 men and 36 women specified if they had Raynaud's phenomenon and also if they had used hand-held vibrating machines. Nearly 41% of them had used hand-held vibrating machines and 18% had used vibrating machines at least 2 h each workday. There were 23 men/6 women with Raynaud's phenomenon. 37% reported WF among those participants who were exposed to hand-arm vibration (HAV) and 15% among those not exposed to HAV. Among the participants with hearing loss with daily use of vibrating hand-held tools more than twice as many reports WF compared with participants that did not use vibrating hand-held tools. This could be interpreted as Raynaud's phenomenon could be associated with an increased risk for noise-induced hearing loss. However, the low participation rate limits the generalization of the results from this study.

  12. Derivation of mean impedance curves as a basis for mechanical models of the human hand-arm system.

    PubMed

    Kinne, J; Melzig-Thiel, R

    1996-02-01

    he use of mechanical models of the human hand-arm system in test stands can substitute man in several activities with exposition to vibration. An example is prototype testing of percussion drills. Modelling should be based on ascertained mean impedance curves of the hand-arm system. The method chosen was deriving curves for the three directions by using DIN and ISO standards (such as DIN 45677) as well as comprehensive literature and results of own measurements. At present it can be stated that: Literature is scarce especially with regard to the test conditions. Thus the causes of--sometimes largely--varying test results are difficult or impossible to be traced. There is conformity with the standards in principle. However, deviations exist for the frequency range determining the aw-value so that the application of mean standard curves for modelling the hand-arm system can lead to mistakes compared to test persons. Literature clearly shows an influence of hand grip force on the impedance curves. Standardisation seems not to consider this influence sufficiently. Mechanical models should take it into account. For feed force, there is no evidence for such a clear influence on the impedance curves.

  13. A Biomechanical Assessment of Hand/Arm Force with Pneumatic Nail Gun Actuation Systems

    PubMed Central

    Lowe, Brian D.; Albers, James; Hudock, Stephen D.

    2015-01-01

    A biomechanical model is presented, and combined with measurements of tip press force, to estimate total user hand force associated with two pneumatic nail gun trigger systems. The contact actuation trigger (CAT) can fire a nail when the user holds the trigger depressed first and then “bumps” the nail gun tip against the workpiece. With a full sequential actuation trigger (SAT) the user must press the tip against the workpiece prior to activating the trigger. The SAT is demonstrably safer in reducing traumatic injury risk, but increases the duration (and magnitude) of tip force exertion. Time integrated (cumulative) hand force was calculated for a single user from measurements of the tip contact force with the workpiece and transfer time between nails as inputs to a static model of the nail gun and workpiece in two nailing task orientations. The model shows the hand force dependence upon the orientation of the workpiece in addition to the trigger system. Based on standard time allowances from work measurement systems (i.e. Methods-Time Measurement - 1) it is proposed that efficient application of hand force with the SAT in maintaining tip contact can reduce force exertion attributable to the sequential actuation trigger to 2–8% (horizontal nailing) and 9–20% (vertical nailing) of the total hand/arm force. The present model is useful for considering differences in cumulative hand/arm force exposure between the SAT and CAT systems and may explain the appeal of the CAT trigger in reducing the user’s perception of muscular effort. PMID:26321780

  14. Vibration-induced disruption of retrograde axoplasmic transport in peripheral nerve.

    PubMed

    Yan, Ji-Geng; Matloub, Hani S; Sanger, James R; Zhang, Lin-Ling; Riley, Danny A

    2005-10-01

    Hand-arm vibration syndrome (HAVS) results from excessive exposure to hand-transmitted vibration. Whether the peripheral nerve damage characteristic of HAVS is a direct result of vibration or is secondary to vascular insufficiency remains unclear. The purpose of this study was to explore the effect of vibration exposure on axoplasmic transport in peripheral nerves and soleus motor neurons. Sciatic nerves and motor neurons from rats following two 5-h periods of vibration exposure demonstrated disruption in retrograde transport compared to normal. After 10 days of vibration (5 h/day), axoplasmic transport failed to recover within 24-48 h in most rats. This study demonstrates that disrupted axoplasmic transport is an early consequence of short-term vibration exposure. The effects of vibration on axoplasmic transport also appear to be cumulative. This study provides a new biological way to evaluate measures to prevent early vibration injury.

  15. Return to Flying Duties Following Centrifuge or Vibration Exposures

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Clarke, Jonathan; Jones, Jeffrey A.

    2009-01-01

    Introduction: In an effort to determine the human performance limits for vibration in spacecraft being developed by NASA, astronauts were evaluated during a simulated launch profile in a centrifuge/vibration environment and separate vibration-only simulation. Current USAF and Army standards for return to flight following centrifuge exposures require 12-24 hours to pass before a crewmember may return to flying duties. There are no standards on vibration exposures and return to flying duties. Based on direct observation and provocative neurological testing of the astronauts, a new standard for return to flying duties following centrifuge and/or vibration exposures was established. Methods: 13 astronaut participants were exposed to simulated launch profiles in a + 3.5 Gx bias centrifuge/vibration environment and separately on a vibration table at the NASA-Ames Research Center. Each subject had complete neurological evaluations pre- and post-exposure for the centrifuge/vibration runs with the NASA neurological function rating scale (NFRS). Subjects who participated in the vibration-only exposures had video oculography performed with provocative maneuvers in addition to the NFRS. NFRS evaluations occurred immediately following each exposure and at 1 hour post-run. Astronauts who remained symptomatic at 1 hour had repeat NFRS performed at 1 hour intervals until the crewmember was asymptomatic. Results: Astronauts in the centrifuge/vibration study averaged a 3-5 point increase in NFRS scores immediately following exposure but returned to baseline 3 hours post-run. Subjects exposed to the vibration-only simulation had a 1-3 point increase following exposure and returned to baseline within 1-2 hours. Pre- and post- vibration exposure video oculography did not reveal any persistent ocular findings with provocative testing 1 hour post-exposure. Discussion: Based on direct observations and objective measurement of neurological function in astronauts following simulated launch

  16. [Criterial value of oxidative stress parameters in exposure to vibration].

    PubMed

    Kriuchkova, E N; Antoshina, L I; Zheglova, A V; Saarkoppel', L M

    2016-01-01

    The article covers results of study concerning metabolic processes in workers exposed to vibration. Findings are lipid peroxidation processes activation, depressed anti-oxidant system, changes in intracellular exchange processes, dependence of the studied parameters change on length of service with vibration exposure.

  17. Endurance time, muscular activity and the hand/arm tremor for different exertion forces of holding.

    PubMed

    Lee, Tzu-Hsien

    2016-01-01

    This study aimed to examine the effects of exertion force on endurance time, muscular activity and hand/arm tremor during holding. Fifteen healthy young males were recruited as participants. The independent variable was exertion force (20%, 40%, 60% and 80% maximum holding capacity). The dependent variables were endurance time, muscular activity and hand/arm tremor. The results showed that endurance time decreased with exertion force while muscular activity and hand/arm tremor increased with exertion force. Hand/arm tremor increased with holding time. Endurance time of 40%, 60% and 80% maximum holding capacity was approximately 22.7%, 12.0% and 5.6% of that of 20% maximum holding capacity, respectively. The rms (root mean square) acceleration of hand/arm tremor of the final phase of holding was 2.27-, 1.33-, 1.20- and 1.73-fold of that of the initial phase of holding for 20%, 40%, 60% and 80% maximum holding capacity, respectively.

  18. An effect of weightlessness following exposure to vibration.

    PubMed

    Gray, S W; Edwards, B F

    1970-01-01

    Vibration of germinating wheat seedlings at the levels experienced during the launch of the NASA Biosatellite II increases the frequency of developmental arrest in seedling organs. Severe vibrations lasted approximately 30 sec in two stages. Power spectral density was greatest at frequencies around 15-16 and 19-22 Hz on the entire vehicle. Vibration forces reaching the affected parts of individual seedlings could not be measured. One or more seedling organs may be expected to be absent in 11% of selected Earth-grown wheat plants. If subjected to simulated launch vibration between 12 and 27 hr after the start of germination, the number of abnormal plants rises to 21.6%. Lateral roots are most affected by vibration at this age. Seedlings which went into orbital weightlessness aboard Biosatellite II, or were grown for several days on a horizontal clinostat after vibration, showed only 5.3% abnormalities. Simulated weightlessness on the clinostat without prior vibration did not alter the number of abnormal plants. It is suggested that growth in weightlessness following exposure to vibration permits more extensive repair of injury produced by vibration than does growth in Earth's gravity.

  19. Vibration on board and health effects.

    PubMed

    Jensen, Anker; Jepsen, Jørgen Riis

    2014-01-01

    There is only limited knowledge of the exposure to vibrations of ships' crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places, seafarers are also exposed to vibrations to the feet when standing on vibrating surfaces on board. Anecdotal reports have related the development of "white feet" to local exposure to vibration, e.g. in mining, but this connection has not been investigated in the maritime setting. As known from studies of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships' passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence for such relation among seafarers except for fishermen, who, however, are also exposed to additional recognised physical risk factors at work. The assessment and reduction of vibrations by naval architects relates to technical implications of this impact for the ships' construction, but has limited value for the estimation of health risks because they express the vibration intensity differently that it is done in a medical context. PMID:25231326

  20. Quantitative thermal perception thresholds relative to exposure to vibration

    PubMed Central

    Nilsson, T; Lundstrom, R

    2001-01-01

    OBJECTIVES—To assess the risk of disturbed thermal perception relative to exposure to vibration, to investigate a possible exposure-response relation and to analyse a possible relation between thermal perception and sensory symptoms.
METHODS—The study was based on a cross section of 123 male workers exposed to vibration and 62 male workers who were not exposed. Thermal perception of cold, warmth, and heat pain was bilaterally determined from the thenar eminence by the method of limits. Perception of cold and warmth were also tested in the second digit. Personal energy equivalent exposure to vibration was measured for all subjects. Vibration was measured in accordance with International Standards Organisation (ISO) 5349 and assessed separately for the left and right hand.
RESULTS—Combining exposure times and intensities gave the left hand an 0.80 exposure to vibration compared with the right. The risk of having contracted reduced thermal perception was increased at all test sites. The risk was higher for the thenar measurements than the finger measurements. A yearly extra contribution of 4000 mh/s2 in cumulative exposure increases the risk of contracting a wider neutral zone by 18% (95% confidence interval (95% CI) 1.06 to 1.32) for the right and 18% (1.05 to 1.32) for the left hand side. Subjects with symptoms of nocturnal paraesthesia had a rate ratio (95% CI) of 2.80 (1.17 to 6.67) for the right hand and 2.72 (1.12 to 6.63) for the left hand for increased neutral zones at the thenar eminence.
CONCLUSIONS—The results indicate thermal sensory impairment related to cumulative exposure to vibration. The effect appeared at vibration levels below the current guiding standard. Quantitative sensory testing of thermal perception offers the chance to assess this specific hazard to the peripheral sensorineural system associated with hand intensive work entailing vibration.


Keywords: quantitative thermal perception; heat pain; vibration

  1. Intensification of flotation treatment by exposure to vibration.

    PubMed

    Ivanov, M V; Ksenofontov, B S

    2014-01-01

    In this paper, an intensification of wastewater flotation treatment by exposure to vibration is studied. Exposure to vibration results in the decrease of air bubble size, increase of air flow through the aerator and more even dispersion of air bubbles in water. This intensifies the aeration process, thus significantly improving the treatment efficiency. A multistage model of flotation kinetics has been applied in order to take into consideration the effects of vibration. The model gives a thorough explanation of the flotation process with consideration of 'air bubble - contaminant particle' aggregate formation. A large series of experiments was conducted with paint and varnish industry wastewaters. It is shown that vibroflotation results in an increase of treatment efficiency by up to three times. A comparison of the experimental data with the results of mathematical modeling is presented, showing a good correlation of theoretical and experimental results.

  2. Moving Events in Time: Time-Referent Hand-Arm Movements Influence Perceived Temporal Distance to Past Events

    ERIC Educational Resources Information Center

    Blom, Stephanie S. A. H.; Semin, Gun R.

    2013-01-01

    We examine and find support for the hypothesis that time-referent hand-arm movements influence temporal judgments. In line with the concept of "left is associated with earlier times, and right is associated with later times," we show that performing left (right) hand-arm movements while thinking about a past event increases (decreases) the…

  3. Persistent reduction of conduction velocity and myelinated axon damage in vibrated rat tail nerves.

    PubMed

    Loffredo, Michael A; Yan, Ji-Geng; Kao, Dennis; Zhang, Lin Ling; Matloub, Hani S; Riley, Danny A

    2009-06-01

    Prolonged hand-transmitted vibration exposure in the workplace has been recognized for almost a century to cause neurodegenerative and vasospastic disease. Persistence of the diseased state for years after cessation of tool use is of grave concern. To understand persistence of vibration injury, the present study examined recovery of nerve conduction velocity and structural damage of myelinated axons in a rat tail vibration model. Both 7 and 14 days of vibration (4 h/day) decreased conduction velocity. The decrease correlated directly with the increased percentage of disrupted myelinated axons. The total number of myelinated axons was unchanged. During 2 months of recovery, conduction velocity returned to control level after 7-day vibration but remained decreased after 14-day vibration. The rat tail model provides insight into understanding the persistence of neural deficits in hand-arm vibration syndrome.

  4. [Exposure to noise, vibration and radiation in Cracow].

    PubMed

    Jarosz, A; Zołdak, M

    1990-01-01

    The problems are discussed connected with exposure to noise, vibration and ionizing radiation. In Cracow traffic and industrial noise is particularly troublesome. The greatest intensity of traffic noise is in the old part of the city and noise level caused by city transport is from 65 to 85 dB/A. Among the industrial sources of noise the highest intensity is in the Lenin Steel Plant, Leg Electrothermal Plant, and Solway Soda Works. Vibration and ionizing radiation resulting from the industrial activities are a considerable risk for human health in the Cracow area. The building materials in construction (including apartment houses) have sometimes a high radioactivity, e.g. dust-slag hollow bricks. The need is stressed for solving, if possible, the problem of noise, especially traffic noise, which is connected with considerable financial costs; the question of using materials of high radioactivity for building purposes should be also resolved.

  5. Vibration exposure and vibration-induced white finger due to chain saw operation.

    PubMed

    Futatsuka, M; Ueno, T

    1985-04-01

    A longitudinal study was undertaken to evaluate changes in the prevalence of vibration-induced white finger (VWF) during the period 1956 to 1980 among a population of Japanese state forestry workers. The vibration levels in the measurements occasionally exceeded the 30-minute line proposed by the Draft International Standard ISO/DIS 5349 in one-third octave bands mainly centered on 160 Hz, with 500 Hz in vertical, 400 Hz in sideways, and 250 Hz in back-and-forth sawing operations. The peak prevalence rate was 62.6%, found in the cohort beginning in 1958-1959. Beginning with the 1968-1969 cohort, the prevalence decreased significantly. During the study period, prevalence rates were approximately 10%, 15%, 20%, 25%, 30%, 35%, and 40% after 2, 3, 4, 5, 7, 9, and 12 years of exposure, respectively. The incidence rate increased gradually after 1960 and the peak value was reached in 1966. The peak value of the incidence rate by duration of exposure was about the same (8% to 10%) in the 1958, 1962, and 1966 cohorts; however, in later groups, the incidence rate decreased in the earlier stages of the exposure periods. The latent interval for the development of VWF was 6.4 +/- 3.7 years (6,000 to 7,000 hours) on average, with a 90% range of one to 14 years (700 to 16,000 hours). Of 452 study subjects with VWF (prevalence rate, 33.5%), 13.5% recovered within the exposure periods, 12.2% recovered within one year after the cessation of exposure, and 74.3% still had VWF more than two years after exposure had ended.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Teleoperation of a robot manipulator from 3D human hand-arm motion

    NASA Astrophysics Data System (ADS)

    Kofman, Jonathan; Verma, Siddharth; Wu, Xianghai; Luu, Timothy

    2003-10-01

    The control of a robot manipulator by a human operator is often necessary in unstructured dynamic environments with unfamiliar objects. Remote teleoperation is required when human presence at the robot site is undesirable or difficult, such as in handling hazardous materials and operating in dangerous or inaccessible environments. Previous approaches have employed mechanical or other contacting interfaces which require unnatural motions for object manipulation tasks or hinder dexterous human motion. This paper presents a non-contacting method of teleoperating a robot manipulator by having the human operator perform the 3D human hand-arm motion that would naturally be used to compete an object manipulation task and tracking the motion with a stereo-camera system at a local site. The 3D human hand-arm motion is reconstructed at the remote robot site and is used to control the position and orientation of the robot manipulator end-effector in real-time. Images captured of the robot interacting with objects at the remote site provide visual feedback to the human operator. Tests in teleoperation of the robot manipulator have demonstrated the ability of the human to carry out object manipulator tasks remotely and the teleoperated robot manipulator system to copy human-arm motions in real-time.

  7. Prevalence of vibration-induced white finger and assessment of vibration exposure among travertine workers in Italy.

    PubMed

    Bovenzi, M; Franzinelli, A; Strambi, F

    1988-01-01

    Among 76 stonedrillers and stonecutters/chippers working in the Rapolano travertine quarries (Tuscany, Italy), 27 subjects (35.5%) were affected with vibration-induced white finger (VWF). The median latent period for VWF was ten years (range 0.1-26 years). A VWF prevalence of 8% was found among 60 comparable controls (P less than 0.0001). Vibration measurements showed that the frequency-weighted accelerations for two rock-drills and two small chipping hammers ranged from 19.7 to 36.4 m/s2. Weighted accelerations between 2.4 and 4.1 m/s2 were measured on the handles of a vertical grinder and a hand cutter. Vibration data, daily exposure time and total duration of exposure period were used to calculate two indicators of vibration dose such as the four-hour, energy-equivalent, frequency-weighted acceleration (m/s2) and the vibration exposure level (dB). A significant association between the vibration exposure level and the severity of VWF stages was observed among the travertine operators. The dose-effect relationship proposed by ISO 5349 was not suitable for the data of the present study because it overestimates the risk due to hand-transmitted vibration in the travertine workers. Finally, the results of a cold test indicated that the rewarming time of fingertips to room temperature was more prolonged in the operators with VWF than in those without VWF and in the controls. PMID:3198281

  8. Combined effects of noise, vibration, and low temperature on the physiological parameters of labor employees.

    PubMed

    Chao, Pao-Chiang; Juang, Yow-Jer; Chen, Chiou-Jong; Dai, Yu-Tung; Yeh, Ching-Ying; Hu, Ching-Yao

    2013-10-01

    Noise, vibration, and low temperature render specific occupational hazards to labor employees. The purpose of this research was to investigate the combined effects of these three physical hazards on employees' physiological parameters. The Taguchi experimental method was used to simulate different exposure conditions caused by noise, vibration, and low temperature, and their effects on the physiological parameters of the test takers were measured. The data were then analyzed using statistical methods to evaluate the combined effects of these three factors on human health. Results showed that the factor that influenced the finger skin temperature, manual dexterity, and mean artery pressure (MAP) most was air temperature, and exposure time was the second most influential factor. Noise was found to be the major factor responsible for hearing loss; in this case, hand-arm vibration and temperature had no effect at all. During the study, the temperature was confined in the 5-25°C range (which was not sufficient to study the effects at extremely high- and low-temperature working conditions) because the combined effects of even two factors were very complicated. For example, the combined effects of hand-arm vibration and low temperature might lead to occupational hazards such as vibration-induced white finger syndrome in working labors. Further studies concerning the occupational damage caused by the combined effects of hazardous factors need to be conducted in the future.

  9. Exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments.

    PubMed

    Sharp, Calum; Woodcock, James; Sica, Gennaro; Peris, Eulalia; Moorhouse, Andrew T; Waddington, David C

    2014-01-01

    In this work, exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments are developed, so as to better understand the differences in human response to these two sources of environmental vibration. Data for this research come from a field study comprising interviews with respondents and measurements of their vibration exposure (N = 752). A logistic regression model is able to accurately classify 96% of these measured railway vibration signals as freight or passenger based on two signal properties that quantify the duration and low frequency content of each signal. Exposure-response relationships are then determined using ordinal probit modeling with fixed thresholds. The results indicate that people are able to distinguish between freight and passenger railway vibration, and that the annoyance response due to freight railway vibration is significantly higher than that due to passenger railway vibration, even for equal levels of exposure. In terms of a community tolerance level, the population studied is 15 dB (re 10(-6) m s(-2)) more tolerant to passenger railway vibration than freight railway vibration. These results have implications for the expansion of freight traffic on rail, or for policies to promote passenger railway.

  10. Exposure-response relationship for vibration-induced white finger among forestry workers.

    PubMed

    Bovenzi, M; Franzinelli, A; Mancini, R; Cannava, M G; Maiorano, M; Ceccarelli, F

    1996-02-01

    The relation between the occurrence of white finger and vibration exposure was investigated in a group of 222 forestry workers using chain saws. The forestry workers and 195 controls never exposed to hand-transmitted vibration were interviewed by occupational health physicians. The diagnosis of vibration-induced white finger (VWF) was made on the basis of subjective symptoms of finger blanching and the results of a cold test with plethysmographic measurement of finger systolic blood pressure. Vibration was measured on a representative sample of AV and non-AV chain saws. Daily vibration exposure was assessed in terms of 8 h energy-equivalent frequency-weighted acceleration [A(8)]. A lifetime vibration dose was estimated for each of the forestry workers. The overall prevalence of VWF among the forestry workers was 23.4%. Raynaud's phenomenon was discovered in 2.6% of the controls. In the forestry workers, the risk of VWF showed positive increments with each increment of vibration dose, suggesting a monotonic dose-response relationship. The responsiveness to cold in the digital arteries of the forestry workers was also found to increase with increasing vibration dose. The estimated relation between VWF and vibration exposure showed that the expected occurrence of VWF increased in approximately linear proportion to either A(8) (with exposure duration unchanged) or the number of years of exposure (with equivalent acceleration unchanged). In this study of VWF among forestry workers the estimated exposure-response relation showed that if the magnitude of vibration acceleration is doubled, the total duration of exposure should be halved to produce an equivalent effect. On the basis of the assessment of vibration exposure, the estimated risk for VWF in the study population was found to be lower than that predicted by the International Standard ISO 5349. The results of this study tend to support the vibration exposure levels currently under discussion within the European

  11. Haemodynamic changes in ipsilateral and contralateral fingers caused by acute exposures to hand transmitted vibration.

    PubMed Central

    Bovenzi, M; Griffin, M J

    1997-01-01

    OBJECTIVES: To investigate changes in digital circulation during and after exposure to hand transmitted vibration. By studying two frequencies and two magnitudes of vibration, to investigate the extent to which haemodynamic changes depend on the vibration frequency, the vibration acceleration, and the vibration velocity. METHODS: Finger skin temperature (FST), finger blood flow (FBF), and finger systolic pressure were measured in the fingers of both hands in eight healthy men. Indices of digital vasomotor tone-such as critical closing pressure and vascular resistance-were estimated by pressure-flow curves obtained with different hand heights. With a static load of 10 N, the right hand was exposed for 30 minutes to each of the following root mean squared (rms) acceleration magnitudes and frequencies of vertical vibration: 22 m.s-2 at 31.5 Hz, 22 m.s-2 at 125 Hz, and 87 m.s-2 at 125 Hz. A control condition consisted of exposure to the static load only. The measures of digital circulation and vasomotor tone were taken before exposure to the vibration and the static load, and at 0, 20, 40, and 60 minutes after the end of each exposure. RESULTS: Exposure to static load caused no significant changes in FST, FBF, or indices of vasomotor tone in either the vibrated right middle finger or the non-vibrated left middle finger. In both fingers, exposure to vibration of 125 Hz and 22 m.s-2 produced a greater reduction in FBF and a greater increase in vasomotor tone than did vibration of 31.5 Hz and 22 m.s-2. In the vibrated right finger, exposure to vibration of 125 Hz and 87 m.s-2 provoked an immediate vasodilation which was followed by vasoconstriction during recovery. The non-vibrated left finger showed a significant increase in vasomotor tone throughout the 60 minute period after the end of vibration exposure. CONCLUSIONS: The digital circulatory response to acute vibration depends upon the magnitude and frequency of the vibration stimulus. Vasomotor mechanisms, mediated

  12. Vibration exposure for selected power hand tools used in automobile assembly.

    PubMed

    Radwin, R G; Armstrong, T J; Vanbergeijk, E

    1990-09-01

    A practical method for assessing vibration exposure for workers operating vibrating hand tools on an automobile assembly line is presented. Vibration exposure is difficult to assess directly using many fast Fourier transform (FFT) spectral analyzers because of long task cycle times. Exposure time cannot be accurately estimated using time standards because of the high variability between operators and work methods. Furthermore, because workers frequently move about and get into inaccessible spaces, it is difficult to record vibration without interfering with the operation. A work sampling method was used for determining vibration exposure time by attaching accelerometers to the tools and suspending a battery-operated digital data logger from the air hose. Vibration acceleration and frequency spectra for each tool were obtained off-line replicating actual working conditions and analyzed together with exposure time data for determining individual worker vibration exposure. Eight pneumatic vibrating power hand tools, representing tools commonly used in an automobile assembly plant, were studied. Spectra for the rotary and reciprocating power tools and had large distinct dominant fundamental frequencies occurring in a narrow frequency range between 35 Hz and 150 Hz. These frequencies corresponded closely to tool free-running speeds, suggesting that major spectral component frequencies may be predicted on the basis of speed for some tools. PMID:2220569

  13. Design of measurement methodology for the evaluation of human exposure to vibration in residential environments.

    PubMed

    Sica, G; Peris, E; Woodcock, J S; Moorhouse, A T; Waddington, D C

    2014-06-01

    Exposure-response relationships are important tools for policy makers to assess the impact of an environmental stressor on the populace. Their validity lies partly in their statistical strength which is greatly influenced by the size of the sample from which the relationship is derived. As such, the derivation of meaningful exposure-response relationships requires estimates of vibration exposure at a large number of receiver locations. In the United Kingdom a socio-vibrational survey has been conducted with the aim of deriving exposure-response relationships for annoyance due to vibration from (a) railway traffic and (b) the construction of a new light rail system. Response to vibration was measured via a questionnaire conducted face-to-face with residents in their own homes and vibration exposure was estimated using data from a novel measurement methodology. In total, 1281 questionnaires were conducted: 931 for vibration from railway traffic and 350 for vibration from construction sources. Considering the interdisciplinary nature of this work along with the volume of experimental data required, a number of significant technical and logistical challenges needed to be overcome through the planning and implementation of the fieldwork. Four of these challenges are considered in this paper: the site identification for providing a robust sample of the residents affected, the strategies used for measuring both exposure and response and the coordination between the teams carrying out the social survey and the vibration measurements.

  14. Effect of hand-arm exercise on venous blood constituents during leg exercise

    NASA Technical Reports Server (NTRS)

    Wong, N.; Silver, J. E.; Greenawalt, S.; Kravik, S. E.; Geelen, G.

    1985-01-01

    Contributions by ancillary hand and arm actions to the changes in blood constituents effected by leg exercises on cycle ergometer were assessed. Static or dynamic hand-arm exercises were added to the leg exercise (50 percent VO2 peak)-only control regimens for the subjects (19-27 yr old men) in the two experimental groups. Antecubital venous blood was analyzed at times 0, 15, and 30 min (T0, T15, and T30) for serum Na(+), K(+), osmolality, albumin, total CA(2+), and glucose; blood hemoglobin, hematocrit, and lactic acid; and change in plasma volume. Only glucose and lactate values were affected by additional arm exercise. Glucose decreased 4 percent at T15 and T30 after static exercise, and by 2 percent at T15 (with no change at T30) after dynamic arm exercise. Conversely, lactic acid increased by 20 percent at T30 after static exercise, and by 14 percent by T15 and 6 percent at T30 after dynamic arm exercise. It is concluded that additional arm movements, performed usually when gripping the handle-bar on the cycle ergometer, could introduce significant errors in measured venous concentrations of glucose and lactate in the leg-exercised subjects.

  15. Effects of Exposure to Railway NOISE—A Comparison Between Areas with and Without Vibration

    NASA Astrophysics Data System (ADS)

    Öhrström, E.

    1997-08-01

    This paper presents some of the results of field investigations on effects of exposure to noise and vibration from railway traffic. Effects on annoyance, sleep disturbances and psycho-social well-being as well as disturbance of different activities were evaluated by a postal questionnaire. Fifteen different sites located near railway lines in Sweden were investigated. The study covered areas with different number of trains per 24 hours in area with strong vibration caused by the railway traffic exceeding 2 mm/s as measured in the buildings as well as areas without vibration, or vibration weaker than 1 mm/s. 2833 persons between 18 and 75 years of age participated in the study. This paper presents only the results from two areas with and without vibration and a high number of trains per 24 hours. The results show that railway noise is experienced as more annoying in areas where there is simultaneous exposure to vibration from railway traffic. Disturbance of communication was the most frequently mentioned annoyance reaction, outside and inside the dwelling. To ensure an acceptable environmental quality where less than 5% of the exposed population is rather or very annoyed by railway noise, these noise levels must be below 80LAmaxand below 55LAeqin areas without vibration. In areas with simultaneous exposure to strong vibration, action against vibration or a longer distance between houses and the railway line is needed, corresponding to a 10 dB(A) lower noise level than in areas without vibration.

  16. [Effect of stevia on the picture of peripheral blood under exposure to vibration].

    PubMed

    Adamyan, Ts I; Gevorkyan, E S

    2014-01-01

    There were investigated changes in the peripheral blood of rabbits under prolonged exposure to vibration (5, 10, 20, 30 days). In a separate series of experiments, the nature of changes in the peripheral blood was investigated under the combined action of vibration and stevia leaves. Contained in stevia biologically active substances were found to accelerate metabolism in bone marrow stem cells, promote the compensatory ability of the organism, thereby providing the resistance of the body to the vibration factor.

  17. The Effects of Impact Vibration on Peripheral Blood Vessels and Nerves

    PubMed Central

    KRAJNAK, Kristine M.; WAUGH, Stacey; JOHNSON, Claud; MILLER, G. Roger; XU, Xueyan; WARREN, Christopher; DONG, Ren G.

    2013-01-01

    Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a single bout of impact vibration (15 min exposure, at a dominant frequency of 30 Hz and an unweighted acceleration of approximately 345 m/s2) generated by a riveting hammer. Responsiveness of the ventral tail artery to adrenoreceptor-mediated vasoconstriction and acetylcholine-mediated re-dilation was measured ex vivo. Ventral tail nerves and nerve endings in the skin were assessed using morphological and immunohistochemical techniques. Impact vibration did not alter vascular responsiveness to any factors or affect trunk nerves. However, 4 days following exposure there was an increase in protein-gene product (PGP) 9.5 staining around hair follicles. A single exposure to impact vibration, with the exposure characteristics described above, affects peripheral nerves but not blood vessels. PMID:24077447

  18. Measurement of Whole-Body Vibration Exposure from Garbage Trucks

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Morioka, M.

    1998-08-01

    Japanese garbage truck drivers are exposed to mechanical whole-body vibration during their work. Some drivers have suffered from low back pain from this vibration. However, there is no evidence of a relationship between the whole-body vibration from the garbage trucks and low back pain or occupational disease, due to the lack of investigations. A field study was conducted in order to characterize the health risks associated with garbage truck work. Three different types of truck were tested at different loadings and on different road surfaces, with the vibrations measured at the driver/seat interface (x,y, andz-axes). The vibrations were compared with the health risk guidance according to Annex B of ISO 2631-1 [1]. The findings of this study indicated that Japanese garbage truck drivers should not operate trucks for 2.5 h in a day, under current working conditions.

  19. Vibration induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers

    PubMed Central

    Eger, Tammy; Thompson, Aaron; Leduc, Mallorie; Krajnak, Kristine; Goggins, Katie; Godwin, Alison; House, Ron

    2015-01-01

    BACKGROUND Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk of vibration-induced injury. PARTICIPANTS Workers who operated locomotives (n = 3), bolting platforms (n = 10), jumbo drills (n = 7), raise drilling platforms (n = 4), and crushers (n = 3), participated. METHODS A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury. PMID:24004754

  20. Relation of haemostatic function, neurovascular impairment, and vibration exposure in workers with different stages of vibration induced white finger.

    PubMed Central

    Bovenzi, M; Giansante, C; Fiorito, A; Calabrese, S

    1985-01-01

    Haemostatic function and neurovascular symptoms were investigated in 67 workers exposed to vibration and 46 comparable referents. Of these 65.6% of vibration workers complained of neurological disturbances (stages 0T, 0N of Taylor's classification for vibration induced white finger (VWF) and 20.9% suffered from Raynaud's phenomenon (stages 1-2-3). The severity of the staging symptoms showed a close relation with an index of vibration dose computed on the basis of vibration measurement and individual exposure time. Indices of platelet aggregation, both in vitro and in vivo, antithrombin III, fibrinogen and fibrinopeptide A levels were not different in the exposed workers compared with the referents. No relation was found between haemostatic parameters and the severity of VWF. Exposed workers responded to a cooling procedure with a more pronounced vasoconstriction in the digital vessels than the referents, as indicated by delayed recovery time of finger skin temperature after the cold test. These findings suggest that both in the early stages (0T, 0N) and in more severe stages of VWF (stages 1-2) cold induced hyperreactivity in the digital vessels and Raynaud's syndrome are vascular disorders of functional origin occurring without any prethrombotic alterations. PMID:3978045

  1. Whole body vibration exposures in forklift operators: comparison of a mechanical and air suspension seat.

    PubMed

    Blood, Ryan P; Ploger, James D; Johnson, Peter W

    2010-11-01

    Using a repeated measures design, this study compared differences in whole body vibration (WBV) exposures when 12 forklift operators drove the same forklift with a mechanical suspension and an air suspension seat. A portable PDA-based WBV data acquisition system collected and analysed time-weighted and raw WBV data per ISO 2631-1 and 2631-5 WBV measurement standards. Tri-axial measurements of weighted vibration (A(w)), crest factor, vibration dose values, time-weighted average-peak, raw (+) peak, raw (-) peak and static compression dose (S(ed)) were compared between seats. There were significant differences in z-axis WBV exposures with the air suspension seat, yielding lower WBV exposures. In addition, there were differences between seats in how they attenuated WBV exposures based on the driver's weight. In the mechanical suspension seat, WBV exposures were weight-dependent, with lighter drivers having higher WBV exposures, whereas with the air suspension seat, the same trends were not as prevalent. STATEMENT OF RELEVANCE: This study contributes to the understanding of how different seat suspensions can influence WBV transmission and how some components of vibration transmission are dependent on the weight of the driver. Additional systematic studies are needed to quantify how various factors can influence WBV exposures.

  2. Six-degree-of-freedom whole-body vibration exposure levels during routine skidder operations.

    PubMed

    Jack, R J; Oliver, M; Dickey, J P; Cation, S; Hayward, G; Lee-Shee, N

    2010-05-01

    This research focuses on quantifying six-degree-of-freedom (6-DOF) whole-body vibration (WBV) exposure levels that occur in Northern Ontario skidders during routine field operating tasks. 6-DOF vibration running root-mean-square (RMS) acceleration levels at the operator/seat interface were determined for eight skidders while driving loaded, driving unloaded, picking up a load, dropping off a load and ploughing logs under field operating conditions. The acceleration data were weighted in accordance with ISO 2631-1:1997 and evaluated for both health and comfort outcomes. The mean running RMS weighted translational and rotational accelerations all exceeded 0.36 m/s(2) and 0.14 rad/s(2). The greatest average accelerations occurred while driving unloaded with this condition displaying translational vibration total values (VTV) that exceeded the upper limit of the ISO 2631-1:1997 health caution zone within an average of 2.3 h. Utilizing 6-DOF VTV, virtually all operating conditions would be designated as uncomfortable. STATEMENT OF RELEVANCE: This study provides one of the most comprehensive reports on vibration exposures in seated vehicle operators. The results are geared towards ergonomists with discussions on health effects and measurement concerns, while providing the raw vibration exposure data that will be useful to vehicle, component and vibration sensor designers.

  3. Validity of self reported occupational exposures to hand transmitted and whole body vibration

    PubMed Central

    Palmer, K.; Haward, B.; Griffin, M.; Bendall, H.; Coggon, D.

    2000-01-01

    OBJECTIVES—To assess the accuracy with which workers report their exposure to occupational sources of hand transmitted (HTV) and whole body vibration (WBV).
METHODS—179 Workers from various jobs involving exposure to HTV or WBV completed a self administered questionnaire about sources of occupational exposure to vibration in the past week. They were then observed at work over 1 hour, after which they completed a second questionnaire concerning their exposures during this observation period. The feasibility of reported sources of exposure during the past week was examined by questioning managers and by inspection of tools and machines in the workplace. The accuracy of reported sources and durations of exposure in the 1 hour period were assessed relative to what had been observed.
RESULTS—The feasibility of exposure in the previous week was confirmed for 97% of subjects who reported exposure to HTV, and for 93% of subjects who reported exposure to WBV. The individual sources of exposure reported were generally plausible, but occupational use of cars was substantially overreported, possibly because of confusion with their use in travel to and from work. The accuracy of exposures reported during the observation period was generally high, but some sources of HTV were confused—for example, nailing and stapling guns reported as riveting hammers, and hammer drills not distinguished from other sorts of drill. Workers overestimated their duration of exposure to HTV by a median factor of 2.5 (interquartile range (IQR) 1.6-5.9), but estimated durations of exposure were more accurate when the exposure was relatively continuous rather than for intermittent short periods. Reported durations of exposure to WBV were generally accurate (median ratio of reported to observed time 1.1, IQR 1.0-1.2).
CONCLUSIONS—Sources of recent occupational exposure to vibration seem to be reported with reasonable accuracy, but durations of exposure to HTV are systematically

  4. Hand-arm bimanual intensive therapy including lower extremities (HABIT-ILE) for children with cerebral palsy.

    PubMed

    Bleyenheuft, Yannick; Gordon, Andrew M

    2014-11-01

    Hand-arm bimanual intensive therapy and constrained-induced movement therapy have shown evidence of effectiveness in improvement of upper extremity use in children with unilateral spastic cerebral palsy (CP). The effectiveness of interventions that are based on intensive practice of activities that combine UE and LE functions has not been reported. We propose that bimanual UE activities that simultaneously require trunk and LE postural adaptations uniquely address motor control limitations of children with unilateral spastic CP. The aim of this perspective is to present such an approach Hand Arm Bimanual Intensive Therapy Including Lower Extremities (HABIT-ILE). HABIT-ILE is unique in selection of tasks and activities that require simultaneous control and coordination of UE and LE movements. It is a motor-learning-based approach using problem solving and highly structured practice. During the intervention, activities and tasks are progressively graded toward more complex bimanual coordination for the UE and increasing demands of the LE. HABIT-ILE is provided in small groups for 90 hr using a camp model. Future research (randomized controlled trial) is needed to determine the effectiveness of HABIT-ILE. PMID:25271469

  5. Exploring the effects of seated whole body vibration exposure on repetitive asymmetric lifting tasks.

    PubMed

    Mehta, Jay P; Lavender, Steven A; Jagacinski, Richard J; Sommerich, Carolyn M

    2015-01-01

    This study investigated changes in the physiological and behavioral responses to repetitive asymmetric lifting activity after exposure to whole body vibrations. Seventeen healthy volunteers repeatedly lifted a box (15% of lifter's capacity) positioned in front of them at ankle level to a location on their left side at waist level at the rate of 10 lifts/min for a period of 60 minutes. Prior to lifting, participants were seated on a vibrating platform for 60 minutes; in one of the two sessions the platform did not vibrate. Overall, the physiological responses assessed using near-infrared spectroscopy signals for the erector spinae muscles decreased significantly over time during the seating and the lifting tasks (p < 0.001). During repetitive asymmetric lifting, behavioral changes included increases in peak forward bending motion, twisting movement, and three-dimensional movement velocities of the spine. The lateral bending movement of the spine and the duration of each lift decreased significantly over the 60 minutes of repetitive lifting. With exposure to whole body vibration, participants twisted farther (p = 0.046) and twisted faster (p = 0.025). These behavioral changes would suggest an increase in back injury risk when repetitive lifting tasks are preceded by whole body vibration exposure.

  6. Exploring the effects of seated whole body vibration exposure on repetitive asymmetric lifting tasks.

    PubMed

    Mehta, Jay P; Lavender, Steven A; Jagacinski, Richard J; Sommerich, Carolyn M

    2015-01-01

    This study investigated changes in the physiological and behavioral responses to repetitive asymmetric lifting activity after exposure to whole body vibrations. Seventeen healthy volunteers repeatedly lifted a box (15% of lifter's capacity) positioned in front of them at ankle level to a location on their left side at waist level at the rate of 10 lifts/min for a period of 60 minutes. Prior to lifting, participants were seated on a vibrating platform for 60 minutes; in one of the two sessions the platform did not vibrate. Overall, the physiological responses assessed using near-infrared spectroscopy signals for the erector spinae muscles decreased significantly over time during the seating and the lifting tasks (p < 0.001). During repetitive asymmetric lifting, behavioral changes included increases in peak forward bending motion, twisting movement, and three-dimensional movement velocities of the spine. The lateral bending movement of the spine and the duration of each lift decreased significantly over the 60 minutes of repetitive lifting. With exposure to whole body vibration, participants twisted farther (p = 0.046) and twisted faster (p = 0.025). These behavioral changes would suggest an increase in back injury risk when repetitive lifting tasks are preceded by whole body vibration exposure. PMID:25264920

  7. Multi-body dynamics modelling of seated human body under exposure to whole-body vibration.

    PubMed

    Yoshimura, Takuya; Nakai, Kazuma; Tamaoki, Gen

    2005-07-01

    In vehicle systems occupational drivers might expose themselves to vibration for a long time. This may cause illness of the spine such as chronic lumbago or low back pain. Therefore, it is necessary to evaluate the influence of vibration to the spinal column and to make up appropriate guidelines or counter plans. In ISO2631-1 or ISO2631-5 assessment of vibration effects to human in the view of adverse-health effect was already presented. However, it is necessary to carry out further research to understand the effect of vibration to human body to examine their validity and to prepare for the future revision. This paper shows the detail measurement of human response to vibration, and the modelling of the seated human body for the assessment of the vibration risk. The vibration transmissibilities from the seat surface to the spinal column and to the head are measured during the exposure to vertical excitation. The modal paramters of seated subject are extracted in order to understand the dominant natural modes. For the evaluation of adverse-health effect the multi-body modelling of the spinal column is introduced. A simplified model having 10 DOFs is counstructed so that the transmissibilities of the model fit to those of experiment. The transient response analysis is illustrated when a half-sine input is applied. The relative displacements of vertebrae are evaluated, which can be a basis for the assessment of vibration risk. It is suggested that the multi-body dynamic model is used to evaluate the vibration effect to the spinal column for seated subjects.

  8. Exposure to whole-body vibration in open-cast mines in the Barents region

    PubMed Central

    Burström, Lage; Hyvärinen, Ville; Johnsen, Magnar; Pettersson, Hans

    2016-01-01

    Objectives We aimed to measure and evaluate whole-body vibration (WBV) exposure among drivers of mining vehicles in the Barents region. Study design In the period from November 2012 to August 2014, this cross-sectional study was carried out at 3 mines in Finland, Norway and Sweden as part of the MineHealth project. Methods Measurements of WBV were conducted on the surface of the driver's seat during normal work in accordance with international standards. Personal data on daily exposure times were collected by a questionnaire. Results Measurements were conducted on 95 different mining vehicles both as root mean square (RMS) value and vibration dose value (VDV) representing different manufacturers, models and capacities. Of the 453 miners who answered the questionnaire, 232 indicated that they were exposed to WBV during their working day. The results show that the mean daily exposure time varies between 1.9 and 6.7 h for different vehicles. The calculated mean A(8) could be found in an interval between 0.2 and 1.0 m/s2 and the corresponding 8-h VDV fell between 7 and 17 m/s1.75. Conclusions Exposure to WBV among operators of mining vehicles may be a serious health and safety problem in the mines studied. The employers ought, therefore, take active steps to reduce exposure in accordance with the European vibration directive. Moreover, since some groups of drivers are exposed to vibration that is close to or exceeds the exposure limit values, the employer should take immediate action to reduce exposure below these values. PMID:26864832

  9. Tool-specific performance of vibration-reducing gloves for attenuating palm-transmitted vibrations in three orthogonal directions

    PubMed Central

    Dong, Ren G.; Welcome, Daniel E.; Peterson, Donald R.; Xu, Xueyan S.; McDowell, Thomas W.; Warren, Christopher; Asaki, Takafumi; Kudernatsch, Simon; Brammer, Antony

    2015-01-01

    Vibration-reducing (VR) gloves have been increasingly used to help reduce vibration exposure, but it remains unclear how effective these gloves are. The purpose of this study was to estimate tool-specific performances of VR gloves for reducing the vibrations transmitted to the palm of the hand in three orthogonal directions (3-D) in an attempt to assess glove effectiveness and aid in the appropriate selection of these gloves. Four typical VR gloves were considered in this study, two of which can be classified as anti-vibration (AV) gloves according to the current AV glove test standard. The average transmissibility spectrum of each glove in each direction was synthesized based on spectra measured in this study and other spectra collected from reported studies. More than seventy vibration spectra of various tools or machines were considered in the estimations, which were also measured in this study or collected from reported studies. The glove performance assessments were based on the percent reduction of frequency-weighted acceleration as is required in the current standard for assessing the risk of vibration exposures. The estimated tool-specific vibration reductions of the gloves indicate that the VR gloves could slightly reduce (<5%) or marginally amplify (<10%) the vibrations generated from low-frequency (<25 Hz) tools or those vibrating primarily along the axis of the tool handle. With other tools, the VR gloves could reduce palm-transmitted vibrations in the range of 5%–58%, primarily depending on the specific tool and its vibration spectra in the three directions. The two AV gloves were not more effective than the other gloves with some of the tools considered in this study. The implications of the results are discussed. Relevance to industry Hand-transmitted vibration exposure may cause hand-arm vibration syndrome. Vibration-reducing gloves are considered as an alternative approach to reduce the vibration exposure. This study provides useful information

  10. The preventive effects of apolipoprotein mimetic D-4F from vibration injury-experiment in rats.

    PubMed

    Rowe, David J; Yan, Ji-Geng; Zhang, Lin Ling; Pritchard, Kirkwood A; Kao, Dennis S; Matloub, Hani S; Riley, Danny A

    2011-03-01

    Hand-arm vibration syndrome (HAVS) is a debilitating sequela of neurological and vascular injuries caused by prolonged occupational exposure to hand-transmitted vibration. Our previous study demonstrated that short-term exposure to vibration can induce vasoconstriction and endothelial cell damage in the ventral artery of the rat's tail. The present study investigated whether pretreatment with D-4F, an apolipoprotein A-1 mimetic with known anti-oxidant and vasodilatory properties, prevents vibration-induced vasoconstriction, endothelial cell injury, and protein nitration. Rats were injected intraperitoneally with 3 mg/kg D-4F at 1 h before vibration of the tails for 4 h/day at 60 Hz, 49 m/s(2) r.m.s. acceleration for either 1 or 3 days. Vibration-induced endothelial cell damage was examined by light microscopy and nitrotyrosine immunoreactivity (a marker for free radical production). One and 3-day vibration produced vasoconstriction and increased nitrotyrosine. Preemptive treatment with D-4F prevented these negative changes. These findings suggest that D-4F may be useful in the prevention of HAVS.

  11. Using consumer electronic devices to estimate whole-body vibration exposure.

    PubMed

    Wolfgang, Rebecca; Burgess-Limerick, Robin

    2014-01-01

    The cost and complexity of commercially available devices for measuring whole-body vibration is a barrier to the systematic collection of the information required to manage this hazard at workplaces. The potential for a consumer electronic device to be used to estimate whole-body vibration was assessed by use of an accelerometer calibrator, and by collecting 42 simultaneous pairs of measurements from a fifth-generation iPod Touch and one of two gold standard vibration measurement devices (Svantech SV111 [Svantech, Warsaw, Poland] or Brüel & Kjær 4447 [Brüel & Kjær Sound & Vibration Measurement A/S, Nærum, Denmark]) while driving light vehicles on a variety of different roadway surfaces. While sampling rate limitations make the accelerometer data collected from the iPod Touch unsuitable for frequency analysis, the vibration amplitudes recorded are sufficiently accurate (errors less than 0.1 m/s(2)) to assist workplaces manage whole-body vibration exposures.

  12. Acute exposure to vibration is an apoptosis-inducing stimulus in the vocal fold epithelium.

    PubMed

    Novaleski, Carolyn K; Kimball, Emily E; Mizuta, Masanobu; Rousseau, Bernard

    2016-10-01

    Clinical voice disorders pose significant communication-related challenges to patients. The purpose of this study was to quantify the rate of apoptosis and tumor necrosis factor-alpha (TNF-α) signaling in vocal fold epithelial cells in response to increasing time-doses and cycle-doses of vibration. 20 New Zealand white breeder rabbits were randomized to three groups of time-doses of vibration exposure (30, 60, 120min) or a control group (120min of vocal fold adduction and abduction). Estimated cycle-doses of vocal fold vibration were extrapolated based on mean fundamental frequency. Laryngeal tissue specimens were evaluated for apoptosis and gene transcript and protein levels of TNF-α. Results revealed that terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was significantly higher after 120min of vibration compared to the control. Transmission electron microscopy (TEM) revealed no significant effect of time-dose on the mean area of epithelial cell nuclei. Extrapolated cycle-doses of vibration exposure were closely related to experimental time-dose conditions, although no significant correlations were observed with TUNEL staining or mean area of epithelial cell nuclei. TUNEL staining was positively correlated with TNF-α protein expression. Our findings suggest that apoptosis can be induced in the vocal fold epithelium after 120min of modal intensity phonation. In contrast, shorter durations of vibration exposure do not result in apoptosis signaling. However, morphological features of apoptosis are not observed using TEM. Future studies are necessary to examine the contribution of abnormal apoptosis to vocal fold diseases. PMID:27577014

  13. Vibration and shock exposure of maintenance-of-way vehicles in the railroad industry.

    PubMed

    Johanning, Eckardt

    2011-05-01

    The aim of this study is to investigate and compare vibration and shock measurements of maintenance-of-way vehicles used in the railroad industry for track maintenance and construction. Following international standards (i.e., ISO 2631-1: 1997) and professional guidelines the frequency weighted root-mean-square (r.m.s.) acceleration for each measurement axis, the vector sum, the seat effective amplitude transmissibility (SEAT), the crest factor (CF), the maximum transient vibration value (MTVV), the vibration dose value (VDV), the ratio and the newly proposed shock risk estimation factor 'R' for spinal injury according to ISO 2631-5:2004 were measured and calculated for seven different maintenance-of-way vehicles during revenue service. Furthermore, a proposed alternative spinal injury prediction method, the VibRisk model, which incorporates different typical driver postures and operator physical characteristics was included for comparison with the ISO 2631-5 risk prediction. The results of the vibration exposure measurements depended on vehicle type, track/surface conditions and seat properties, with the tamper and bulldozer showing the highest r.m.s. vibration values. The vector sum (a(v)) results ranged from 0.37 to 0.99 (m/s(2)). Five of seven track maintenance vehicles would exceed the current Whole-body Vibration ACGIH-TLV(®) guideline for an 8 h exposure duration in the vertical axis recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). The measured CF, MTVV/a(w) and VDV/(a(w)·T(1/4)) ratios were at or above the critical ratios in the majority of measurements given by the ISO 2631-1 (1997) and American industry guidelines by the American Conference of Governmental Industrial Hygienists (ACGIH-TLV). Comparing both prediction models for vibration shock risk for parts of the lumbar spine, different risk predictions and inconsistencies were found. The VibRisk model generally suggests different and higher risk of vertebral

  14. Heavy manual work, exposure to vibration and Dupuytren's disease? Results of a surveillance program for musculoskeletal disorders

    PubMed Central

    Descatha, Alexis; Bodin, Julie; Ha, Catherine; Goubault, Pierre; Lebreton, Marine; Chastang, Jean François; Imbernon, Ellen; Leclerc, Annette; Goldberg, Marcel; Roquelaure, Yves

    2012-01-01

    Introduction In view of the debate about occupational factors in Dupuytren’s disease, the aim of this study was to describe the prevalence of the disease in men and its relationship with work exposure, and especially to distinguish heavy manual work with and without significant use of vibrating tools by using data from a surveillance program for musculoskeletal disorders. Method This cross-sectional study was conducted in France between 2002 and 2004. Dupuytren’s disease was diagnosed clinically by one of the 83 occupational physicians involved in the program. Exposure in relation to work status and occupational risk factors was assessed with a self-administered questionnaire, and was categorized according to vibration exposure (defined as use of vibrating tools ≥2h/day), heavy manual work without vibration exposure [defined as use of hand tools ≥2h/day (use of vibrating tools ≥2h/day excluded) and Borg scale ≥15/20] and no form of such exposure. Bivariate and multivariate associations using logistic models were recorded in men and also in those with over 10 years at the same job. Results Of the 2,161 men, 1.3% (n=27) suffered from Dupuytren’s disease (mean age 47.1+/−6.7 years). Heavy manual work without vibration exposure was significantly associated with the disease (adjusted odds ratio - aOR- 3.9[1.3;11.5]) adjusted on age and diabetes), as was the use of vibrating tools (aOR 5.1[2.1;12.2]). These associations remained significant among subjects with over 10 years at the same job, with increases in aOR of 6.1[1.5;25.0] and 10.7[3.4;34.6], respectively. Conclusion Despite the limited number of cases, occupational exposure, including both vibration exposure and heavy manual work without significant vibration exposure, was associated with Dupuytren’s disease. PMID:22213840

  15. Feasibility of caregiver-directed home-based hand-arm bimanual intensive training: A brief report

    PubMed Central

    Ferre, Claudio L.; Brandão, Marina B.; Hung, Ya-Ching; Carmel, Jason B.; Gordon, Andrew M.

    2015-01-01

    Objective To determine feasibility of a home-based, intensive bimanual intervention with children with unilateral spastic cerebral palsy. Methods Eleven children (aged 29–54 months) received 90 hours of home hand-arm bimanual intensive therapy (H-HABIT) provided by their trained caregivers. Parenting stress levels and compliance were monitored using the Parenting Stress Index and daily logs. Quality of bimanual performance and changes in performance/satisfaction of functional goals were assessed using the Assisting Hand Assessment (AHA) and Canadian Occupational Performance Measure (COPM), respectively, at two pretreatment baseline sessions and two posttreatment sessions (immediate and six months). Results Ten children completed the study with caregivers completing on average 85.6 hours of H-HABIT. Daily logs indicated high caregiver compliance. Stress levels remained stable across the intervention. Children demonstrated significant improvements in the AHA and COPM. Conclusion H-HABIT is a feasible intervention for improving hand function and merits further investigation in a randomized-control trial. PMID:25180530

  16. Characterization of vibration and noise exposure in Canadian Forces armored vehicles

    NASA Astrophysics Data System (ADS)

    Nakashima, Ann M.; Borland, Matthew J.; Abel, Sharon M.

    2005-09-01

    A study to characterize the vibration and noise exposure in several Canadian Forces (CF) armored vehicles is in progress. Measurements of whole-body vibration and ambient noise levels are being made in the LAV III, Bison, Coyote, and M113 vehicles at three different positions: driver, crew commander, and passenger bench (or navigator seat in the case of the Coyote). The measurements are being made while the vehicles are idling, driven over rough terrain, and driven at a high speed on paved highways. There are several standards that provide guidance on the measurement and assessment of whole-body vibration, but they are difficult to implement in practice, particularly in adverse environments. The whole-body vibration measurements in this study are particularly difficult to interpret in the case of the crew commander, who often stands on the seat, and the passenger, who is seated but unrestrained by a seatbelt. The preliminary results-suggest, that according to the International Organization for Standardization guidelines (ISO 2631-1:1997), there may be potential health risks for the driver and passenger after driving on rough terrain for less than 10 min. Noise levels were as high as 100 dBA during high-speed highway driving.

  17. Typical whole body vibration exposure magnitudes encountered in the open pit mining industry.

    PubMed

    Howard, Bryan; Sesek, Richard; Bloswick, Don

    2009-01-01

    According to recent research, a causal link has been established between occupational exposure to whole body vibration and an increased occurrence of low back pain. To aid in the further development of an in-house health and safety program for a large open pit mining facility interested in reducing back pain among its operators, whole body vibration magnitudes were characterized for a range of jobs. Specifically, thirty-five individual jobs from five different areas across the facility were evaluated for tri-axial acceleration levels during normal operating conditions. Tri-axial acceleration magnitudes were categorized into thirteen job groups. Job groups were ranked according to exposure and compared to the ISO 2631-1 standard for health risk assessment. Three of the thirteen job groups produced tri-axial acceleration magnitudes below the ISO 2631-1 low/moderate health caution limit for a twelve hour exposure. Six of the thirteen job groups produced exposures within the moderate health risk range. Four job groups were found to subject operators to WBV acceleration magnitudes above the moderate/high health caution limit. PMID:20037244

  18. Whole Body Vibration Exposures and Health Status among Professional Truck Drivers: A Cross-sectional Analysis.

    PubMed

    Kim, Jeong Ho; Zigman, Monica; Aulck, Lovenoor S; Ibbotson, Jennifer A; Dennerlein, Jack T; Johnson, Peter W

    2016-10-01

    Many professional truck drivers suffer from low back pain (LBP) which is thought to be associated with exposure to whole-body vibration (WBV). The objectives of this study were to: (i) characterize general health, regional body pain and WBV exposures, (ii) evaluate the associations between different WBV parameters and health outcomes, and (iii) determine whether there were factors which affect a truck driver's WBV exposures. This study analyzed WBV exposures from 96 long-haul truck drivers over their regular work shift (6-15h) per International Standards Organization (ISO) 2631-1 and 2631-5 WBV standards. This study also evaluated regional body pain (10-point scale), low back disability (the Oswestry Disability Index), and physical and mental health (the Short Form 12-item Health Survey). The results demonstrated that the daily vector sum WBV exposures [A(8), VDV(8) and Sed(8)] were above action limits while the predominant z-axis exposures were below action limits. Among all the musculoskeletal outcomes, LBP was the most prevalent (72.5%) with average LBP score of 2.9 (SD: 2.0). The SF-12 health scores demonstrated that truck drivers in general had lower physical health status than the general US population (P's < 0.04) and that physical health status decreased as WBV exposures increased (P = 0.03). In addition, the correlations between the WBV measures and health outcomes indicated that A(8) exposure measures had a stronger link to musculoskeletal (LBP) and other health outcomes than the VDV(8) and Sed(8) measures. Finally, seat manufacturer and seat age were two factors which had a strong influence on WBV exposures.

  19. Long-term daily vibration exposure alters current perception threshold (CPT) sensitivity and myelinated axons in a rat-tail model of vibration-induced injury.

    PubMed

    Krajnak, Kristine; Raju, Sandya G; Miller, G Roger; Johnson, Claud; Waugh, Stacey; Kashon, Michael L; Riley, Danny A

    2016-01-01

    Repeated exposure to hand-transmitted vibration through the use of powered hand tools may result in pain and progressive reductions in tactile sensitivity. The goal of the present study was to use an established animal model of vibration-induced injury to characterize changes in sensory nerve function and cellular mechanisms associated with these alterations. Sensory nerve function was assessed weekly using the current perception threshold test and tail-flick analgesia test in male Sprague-Dawley rats exposed to 28 d of tail vibration. After 28 d of exposure, Aβ fiber sensitivity was reduced. This reduction in sensitivity was partly attributed to structural disruption of myelin. In addition, the decrease in sensitivity was also associated with a reduction in myelin basic protein and 2',3'- cyclic nucleotide phosphodiasterase (CNPase) staining in tail nerves, and an increase in circulating calcitonin gene-related peptide (CGRP) concentrations. Changes in Aβ fiber sensitivity and CGRP concentrations may serve as early markers of vibration-induced injury in peripheral nerves. It is conceivable that these markers may be utilized to monitor sensorineural alterations in workers exposed to vibration to potentially prevent additional injury. PMID:26852665

  20. Long-term daily vibration exposure alters current perception threshold (CPT) sensitivity and myelinated axons in a rat-tail model of vibration-induced injury.

    PubMed

    Krajnak, Kristine; Raju, Sandya G; Miller, G Roger; Johnson, Claud; Waugh, Stacey; Kashon, Michael L; Riley, Danny A

    2016-01-01

    Repeated exposure to hand-transmitted vibration through the use of powered hand tools may result in pain and progressive reductions in tactile sensitivity. The goal of the present study was to use an established animal model of vibration-induced injury to characterize changes in sensory nerve function and cellular mechanisms associated with these alterations. Sensory nerve function was assessed weekly using the current perception threshold test and tail-flick analgesia test in male Sprague-Dawley rats exposed to 28 d of tail vibration. After 28 d of exposure, Aβ fiber sensitivity was reduced. This reduction in sensitivity was partly attributed to structural disruption of myelin. In addition, the decrease in sensitivity was also associated with a reduction in myelin basic protein and 2',3'- cyclic nucleotide phosphodiasterase (CNPase) staining in tail nerves, and an increase in circulating calcitonin gene-related peptide (CGRP) concentrations. Changes in Aβ fiber sensitivity and CGRP concentrations may serve as early markers of vibration-induced injury in peripheral nerves. It is conceivable that these markers may be utilized to monitor sensorineural alterations in workers exposed to vibration to potentially prevent additional injury.

  1. Elbow joint disorders in relation to vibration exposure and age in stone quarry workers.

    PubMed

    Sakakibara, H; Suzuki, H; Momoi, Y; Yamada, S

    1993-01-01

    Elbow joint disorders were studied in relation to vibration exposure and age in 74 male stone quarry workers who operated mainly chipping hammers and sometimes rock drills. They were examined for range of active motion in elbow extension and flexion, and by means of radiographs of the elbow joint. Effects of age and vibratory tool operation on the elbow joint were statistically estimated using multiple regression analysis. In the analysis of all subjects, including those aged over 60 years, age was significantly related to the range of motion in extension and to radiographic changes in both elbows, and the duration of vibratory tool operation was associated with the range of right elbow flexion. Among subjects under the age of 60 years, duration of vibratory tool operation showed a significant dose-effect relationship to the range of flexion and radiographic changes in the right elbow, but there was no significant relationship with age. The present results suggest that the operation of chipping hammers and rock drills contributes to elbow joint disorders or osteoarthrosis, even when the effect of age is taken into account. Besides vibration exposure, it may be necessary to consider various loads on the elbow joint such as firmly grasping and pressing the tool against stones with the arm bent at about 90 degrees, and carrying stones.

  2. Whole Body Vibration at Different Exposure Frequencies: Infrared Thermography and Physiological Effects

    PubMed Central

    Sonza, Anelise; Robinson, Caroline C.; Achaval, Matilde; Zaro, Milton A.

    2015-01-01

    The aim of this study was to investigate the effects of whole body vibration (WBV) on physiological parameters, cutaneous temperature, tactile sensitivity, and balance. Twenty-four healthy adults (25.3 ± 2.6 years) participated in four WBV sessions. They spent 15 minutes on a vibration platform in the vertical mode at four different frequencies (31, 35, 40, and 44 Hz) with 1 mm of amplitude. All variables were measured before and after WBV exposure. Pressure sensation in five anatomical regions and both feet was determined using Von Frey monofilaments. Postural sway was measured using a force plate. Cutaneous temperature was obtained with an infrared camera. WBV influences the discharge of the skin touch-pressure receptors, decreasing sensitivity at all measured frequencies and foot regions (P ≤ 0.05). Regarding balance, no differences were found after 20 minutes of WBV at frequencies of 31 and 35 Hz. At 40 and 44 Hz, participants showed higher anterior-posterior center of pressure (COP) velocity and length. The cutaneous temperature of the lower limbs decreased during and 10 minutes after WBV. WBV decreases touch-pressure sensitivity at all measured frequencies 10 min after exposure. This may be related to the impaired balance at higher frequencies since these variables have a role in maintaining postural stability. Vasoconstriction might explain the decreased lower limb temperature. PMID:25664338

  3. A case report of vibration-induced hand comorbidities in a postwoman

    PubMed Central

    2011-01-01

    Background Prolonged exposure to hand-transmitted vibration is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and osteoarticular systems of the upper limbs. However, the available epidemiological evidence is derived from studies on high vibration levels caused by vibratory tools, whereas little is known about possible upper limb disorders caused by chronic exposure to low vibration levels emitted by fixed sources. Case presentation We present the case of a postwoman who delivered mail for 15 years using a low-powered motorcycle. The woman was in good health until 2002, when she was diagnosed with bilateral Raynaud's phenomenon. In March 2003 a bilateral carpal tunnel syndrome was electromyographically diagnosed; surgical treatment was ineffective. Further examinations in 2005 highlighted the presence of chronic tendonitis (right middle finger flexor). Risk assessment From 1987, for 15 years, our patient rode her motorcycle for 4 h/day, carrying a load of 20-30 kg. For about a quarter of the time she drove over country roads. Using the information collected about the tasks carried out every day by the postwoman and some measurements performed on both handles of the motorcycle, as well as on both iron parts of the handlebars, we reconstructed the woman's previous exposure to hand-arm vibration. 8-hour energy-equivalent frequency weighted acceleration was about 2.4 m/s2. The lifetime dose was 1.5 × 109(m2/s4)hd. Conclusions The particular set of comorbidities presented by our patient suggests a common pathophysiological basis for all the diseases. Considering the level of exposure to vibrations and the lack of specific knowledge on the effects of vibration in women, we hypothesize an association between the work exposure and the onset of the diseases. PMID:21320318

  4. The physiological effects of simultaneous exposures to heat and vibration. Ph.D. Thesis - California Univ., Berkeley

    NASA Technical Reports Server (NTRS)

    Spaul, W. A.

    1983-01-01

    Determination of the effects of exposure to vibration on the body's ability to handle heat stress, and, if so, identification of the specific vibration parameters (frequency and intensity) for both whole-body (wbv) and segmental-body vibration (sbv) that would have the most detrimental effect on the body's ability to maintain thermal homeostasis were studied. Rectal and skin temperatures, heart rates, localized sweat rates, arm-segment blood perfusion rates, respiration rates, oxygen uptakes, and respiratory exchange ratios were measured in six men (22 to 33 yr) during simultaneous exposures to heat and vibration - either wbv or sbv, and during a heated 50 min recovery period. The heat conditions were T (sub db) = 43.5 + or - 0.5 C (mean + or S.E.M.), and RH = 20 + or - 4%. All vibration exposures were divided into two exposure conditions - identical frequencies but at a high intensity (HI) and a low intensity (LI) level. The HI wbv exposure was for 25 min/day at 5 Hz, 0.37 g-rms; 10 Hz, 0.46 g-rms; 16 Hz, 0.72 g-rms; 30 Hz, 1.40 g-rms; 80 Hz, 3.70 g-rms. The LI wbv exposure was for 2.5 hr/day at the same frequencies but at the following accelerations: 0.14 g-rms; 0.18 g-rms; 0.28 g-rms; 0.55 g-rms; 1.44 g-rms. During the sbv the subject stood and grasped a vibrating, in the Z-axis, hand grip with both hands.

  5. The apparent mass and mechanical impedance of the hand and the transmission of vibration to the fingers, hand, and arm

    NASA Astrophysics Data System (ADS)

    Concettoni, Enrico; Griffin, Michael

    2009-08-01

    Although hand-transmitted vibration causes injury and disease, most often evident in the fingers, the biodynamic responses of the fingers, hand, and arm are not yet well understood. A method of investigating the motion of the entire finger-hand-arm system, based on the simultaneous measurement of the biodynamic response at the driving point and the transmissibility to many points on the finger-hand-arm system, is illustrated. Fourteen male subjects participated in an experiment in which they pushed down on a vertically vibrating metal plate with their right forearm pronated and their elbow bent at 90°. The apparent mass and mechanical impedance of the finger-hand-arm system were measured for each of seven different contact conditions between the plate and the fingers and hand. Simultaneously, the vibration of the fingers, hand, and arm was measured at 41 locations using a scanning laser Doppler vibrometer. Transmissibilities showed how the vibration was transmitted along the arm and allowed the construction of spectral operating deflection shapes showing the vibration pattern of the fingers, hand, and arm for each of the seven contact conditions. The vibration patterns at critical frequencies for each contact condition have been used to explain features in the driving point biodynamic responses and the vibration behaviour of the hand-arm system. Spectral operating deflection shapes for the upper limb assist the interpretation of driving point biodynamic responses and help to advance understanding required to predict, explain, and control the various effects of hand-transmitted vibration.

  6. Assessment of whole-body vibration exposures and influencing factors for quarry haul truck drivers and loader operators

    PubMed Central

    Mayton, Alan G.; Jobes, Christopher C.; Gallagher, Sean

    2015-01-01

    To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines. PMID:26361493

  7. Prevalence and pattern of occupational exposure to whole body vibration in Great Britain: findings from a national survey

    PubMed Central

    Palmer, K.; Griffin, M.; Bendall, H.; Pannett, B.; Coggon, D.

    2000-01-01

    OBJECTIVES—To estimate the number of workers in Great Britain with significant occupational exposure to whole body vibration (WBV) and to identify the common sources of exposure and the occupations and industries where such exposures arise.
METHODS—A postal questionnaire was posted to a random community sample of 22 194 men and women of working age. Among other things, the questionnaire asked about exposure to WBV in the past week, including occupational and common non-occupational sources. Responses were assessed by occupation and industry, and national prevalence estimates were derived from census information. Estimates were also made of the average estimated daily personal dose of vibration (eVDV).
RESULTS—From the 12 907 responses it was estimated that 7.2 million men and 1.8 million women in Great Britain are exposed to WBV at work in a 1 week period if the occupational use of cars, vans, buses, trains, and motor cycles is included within the definition of exposure. The eVDV of >374 000 men and 9000 women was estimated to exceed a proposed British Standard action level of 15 ms-1.75. Occupations in which the estimated exposures most often exceeded 15 ms-1.75 included forklift truck and mechanical truck drivers, farm owners and managers, farm workers, and drivers of road goods vehicles. These occupations also contributed the largest estimated numbers of workers in Great Britain with such levels of exposure. The highest estimated median occupational eVDVs were found in forklift truck drivers, drivers of road goods vehicles, bus and coach drivers, and technical and wholesale sales representatives, among whom a greater contribution to total dose was received from occupational exposures than from non-occupational ones; but in many other occupations the reverse applied. The most common sources of occupational exposure to WBV are cars, vans, forklift trucks, lorries, tractors, buses, and loaders.
CONCLUSIONS—Exposure to whole body vibration is

  8. The role of motion platform on postural instability and head vibration exposure at driving simulators.

    PubMed

    Aykent, B; Merienne, F; Paillot, D; Kemeny, A

    2014-02-01

    This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (ax,sensed=ax_head and ay,sensed=ay_head, ayv=ay_veh and ayv=ay_veh) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (XCP and YCP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r=-.203, p=.154>.05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r=-.066, p=.643>.05) that can be negligible for the dynamic condition. The XCP for the dynamic case indicated a significant higher value than the static situation (t(47), p<.0001). The VDVx for the dynamic case yielded a significant higher value than the static situation (U(47), p<.0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r=-.376, p=.007<.05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r=.418, p=.002<.05) at dynamic platform condition. The VDVy for the static case indicated a significant higher value rather than the dynamic situation (U(47), p<.0001). The YCP for the static case yielded significantly higher than the dynamic situation (t(47), p=.001<0.05).

  9. The role of motion platform on postural instability and head vibration exposure at driving simulators.

    PubMed

    Aykent, B; Merienne, F; Paillot, D; Kemeny, A

    2014-02-01

    This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (ax,sensed=ax_head and ay,sensed=ay_head, ayv=ay_veh and ayv=ay_veh) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (XCP and YCP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r=-.203, p=.154>.05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r=-.066, p=.643>.05) that can be negligible for the dynamic condition. The XCP for the dynamic case indicated a significant higher value than the static situation (t(47), p<.0001). The VDVx for the dynamic case yielded a significant higher value than the static situation (U(47), p<.0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r=-.376, p=.007<.05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r=.418, p=.002<.05) at dynamic platform condition. The VDVy for the static case indicated a significant higher value rather than the dynamic situation (U(47), p<.0001). The YCP for the static case yielded significantly higher than the dynamic situation (t(47), p=.001<0.05). PMID:24321410

  10. Contribution of individual components of a job cycle on overall severity of whole-body vibration exposure: a study in Indian mines.

    PubMed

    Mandal, Bibhuti B; Mansfield, Neil J

    2016-01-01

    Drivers of earth-moving machines are exposed to whole-body vibration (WBV). In mining operations there can be a combination of relatively high magnitudes of vibration and long exposure times. Effective risk mitigation requires understanding of the main aspects of a task that pose a hazard to health. There are very few published studies of WBV exposure from India. This paper reports on a study that considered the contribution of the component phases of dumper operations, on the overall vibration exposure of the drivers. It shows that vibration magnitudes are relatively high, and that haulage tasks are the main contributor to the exposure. It is recommended that driver speed, haul road surfaces and vehicle maintenance/selection are optimized to ensure minimization of vibration. If this is not sufficient, operation times might need to be reduced in order to ensure that the health guidance caution zone from Standard No. ISO 2631-1:1997 is not exceeded.

  11. Prevalence and pattern of occupational exposure to hand transmitted vibration in Great Britain: findings from a national survey

    PubMed Central

    Palmer, K.; Griffin, M.; Bendall, H.; Pannett, B.; Coggon, D.

    2000-01-01

    OBJECTIVES—To estimate the number of workers in Great Britain with significant occupational exposure to hand transmitted vibration (HTV). Also, to identify the occupations and industries where such exposures arise, and the main sources of exposure.
METHODS—A questionnaire was posted to 22 194 men and women aged 16-64, comprising 21 201 subjects selected at random from the age-sex registers of 34 general practices in England, Scotland, and Wales, and a further 993 subjects selected at random from the central pay registers of the three armed services. Among other things, the questionnaire asked about exposure to sources of HTV in current and earlier employment. Responses were assessed by occupation and industry, and prevalence estimates for the country as a whole were derived from census information on occupational and industrial populations nationally. Estimates were also made in exposed workers of the average daily dose of vibration (A(8) root mean squared (rms) for the past week, based on their reported sources and durations of exposure.
RESULTS—Usable questionnaires were returned by 12 907 subjects (overall response rate 58%). From these it was estimated that some 4.2 million men and 667 000 women in Great Britain are exposed to HTV at work in a 1 week period, and that personal daily exposures to vibration exceed a suggested action level equivalent to 2.8 ms-2 for 8 hours (A(8) >2.8 ms-2 rms) in at least 1.2 million men and 44 000 women. High estimated doses (A(8) >5 ms-2 rms) arose most often in bricklayers and masons, gardeners and groundsmen, carpenters and joiners, electricians and electrical maintenance fitters, and builders and building contractors. The industries where high A(8) values most often arose were construction, motor vehicle repair and maintenance, manufacture of basic metals, and agriculture. The most common sources of exposure were hammer drills, hand held portable grinders, and jigsaws.
CONCLUSIONS—Exposure to HTV is

  12. Measurement, evaluation, and assessment of occupational exposures to hand-transmitted vibration.

    PubMed Central

    Griffin, M J

    1997-01-01

    The measurement of hand-transmitted vibration converts oscillatory movements to a form in which they can be evaluated with respect to human responses and assessed for their acceptability. This paper presents methods of measurement, evaluation, and assessment currently advocated in standards and other forms of guidance. The degree to which the methods of evaluating different frequencies, directions, and durations of vibration affect the assessment of vibration on different tools is illustrated. With the frequency weighting currently used to allow for the effects of different frequencies there is little need to measure vibration at frequencies as high as 1000 Hz; this has significant implications to the design and evaluation of proposed antivibration devices, including gloves. Without the current frequency weighting, vibration at frequencies greater than 250 Hz can contribute to the magnitude of the vibration, but many common causes of injury from hand-transmitted vibration have their dominant components of vibration below 250 Hz. On many powered tools, although the dominant frequency of vibration is the same before and after frequency weighting, the reported magnitude of vibration is greatly affected by the frequency weighting. On tools with dominant low frequencies, their vibration is rated as being of far greater importance relative to other tools when considering frequency-weighted acceleration than when considering unweighted acceleration. It is shown that the effect of considering three axes of vibration as opposed to one axis has a greater effect on some tools than on others. The uncertainties and assumptions involved in the measurement, evaluation, and assessment of hand-transmitted vibration are reviewed. It is suggested that whereas current decisions on health and welfare should be based on current assessment methods, the measurement and evaluation of hand-transmitted vibration should involve the collection and reporting of data which allow other

  13. Whole-body Vibration Exposure Intervention among Professional Bus and Truck Drivers: A Laboratory Evaluation of Seat-suspension Designs.

    PubMed

    Blood, Ryan P; Yost, Michael G; Camp, Janice E; Ching, Randal P

    2015-01-01

    Long-term exposure to seated whole-body vibration (WBV) is one of the leading risk factors for the development of low back disorders. Professional bus and truck drivers are regularly exposed to continuous WBV, since they spend the majority of their working hours driving heavy vehicles. This study measured WBV exposures among professional bus and truck drivers and evaluated the effects of seat-suspension designs using simulated field-collected data on a vibration table. WBV exposures were measured and compared across three different seat designs: an air-ride bus seat, an air-ride truck seat, and an electromagnetically active (EM-active) seat. Air-ride seats use a compressed-air bladder to attenuate vibrations, and they have been in operation throughout the transportation industry for many years. The EM-active seat is a relatively new design that incorporates a microprocessor-controlled actuator to dampen vibration. The vibration table simulated seven WBV exposure scenarios: four segments of vertical vibration and three scenarios that used field-collected driving data on different road surfaces-a city street, a freeway, and a section of rough roadway. The field scenarios used tri-axial WBV data that had been collected at the seat pan and at the driver's sternum, in accordance with ISO 2631-1 and 2631-5. This study found that WBV was significantly greater in the vertical direction (z-axis) than in the lateral directions (x-and y-axes) for each of the three road types and each of the three types of seats. Quantitative comparisons of the results showed that the floor-to-seat-pan transmissibility was significantly lower for the EM-active seat than for either the air-ride bus seat or the air-ride truck seat, across all three road types. This study also demonstrated that seat-suspension designs have a significant effect on the vibrations transmitted to vehicle operators, and the study's results may prove useful in designing future seat suspensions.

  14. Apparent mass and cross-axis apparent mass of standing subjects during exposure to vertical whole-body vibration

    NASA Astrophysics Data System (ADS)

    Subashi, G. H. M. J.; Matsumoto, Y.; Griffin, M. J.

    2006-05-01

    The effects of posture and vibration magnitude on the vertical apparent mass and the fore-and-aft cross-axis apparent mass of the standing human body during exposure to vertical vibration have been investigated. Twelve male subjects were exposed to random vertical vibration over the frequency range 2.0-20 Hz at three vibration magnitudes: 0.125, 0.25 and 0.5 m s -2 rms. Subjects stood in five different postures: upright, lordotic, anterior lean, knees bent and knees more bent. The vertical acceleration at the floor and the forces in the vertical and fore-and-aft directions at the floor were used to obtain the apparent mass and the cross-axis apparent mass. The resonance frequency of the apparent mass was significantly reduced with knees bent and knees more bent postures, but there were only minor effects on the resonance frequency by changing the position of the upper body. Considerable cross-axis apparent mass, up to about 30% of the static mass of subjects, was found. The cross-axis apparent mass was influenced by all postural changes used in the study. In all postures the resonance frequencies of the apparent mass and the cross-axis apparent mass tended to decrease with increasing vibration magnitude. This nonlinear characteristic tended to be less clear in some postures in which subjects increased muscle tension.

  15. Vehicle design influences whole body vibration exposures: effect of the location of the front axle relative to the cab.

    PubMed

    Blood, Ryan P; Rynell, Patrik W; Johnson, Peter W

    2011-06-01

    Using a repeated measure design, this study compared differences in whole body vibration (WBV) exposures among 13 drivers who drove a truck with the cab over the front axle (cab-over design) and a truck with the cab situated behind the front axle (non-cab-over design). The drivers drove both trucks over a standardized route that comprised three distinct segments: a freeway segment, a city street segment with stop-and-go driving (traffic lights), and a city street segment without traffic lights. A portable WBV data acquisition system collected tri-axial time-weighted and raw WBV data per ISO 2631-1 and 2631-5 standards. Simultaneous global positioning system (GPS) data were also collected to compare vehicle speeds. The GPS data indicated that there were no speed differences between the two vehicles. However, average and impulsive z-axis vibration levels were significantly higher for the cab-over design than for the non-cab-over design. In addition, significant WBV exposure differences between road types were found, with the freeway segments having the lowest exposures and the city street segments without traffic lights having the highest exposures. Vehicle type and the associated WBV exposures should be considered when purchasing vehicles to be used by full-time professional vehicle operators.

  16. An Updated Review of Epidemiologic Studies on the Relationship Between Exposure to Whole-Body Vibration and Low Back Pain

    NASA Astrophysics Data System (ADS)

    Bovenzi, M.; Hulshof, C. T. J.

    1998-08-01

    The aim of this paper is to update the information on the epidemiologic evidence of the adverse health effects of whole-body vibration (WBV) on the spinal system by means of a review of the epidemiologic studies published between 1986 and 1996. In a systematic search of epidemiologic studies of low back pain (LBP) disorders and occupations with exposure to WBV, 37 articles were retrieved. The quality of each study was evaluated according to criteria concerning the assessment of vibration exposure, assessment of health effects, and methodology. The epidemiologic studies reaching an adequate score on each of the above mentioned criteria, were included in the final review. A meta-analysis was also conducted in order to combine the results of independent epidemiologic studies. After applying the selection criteria, 16 articles reporting the occurrence of LBP disorders in 19 WBV-exposed occupational groups, reached a sufficient score. The study design was cross-sectional for 13 occupational groups, longitudinal for 5 groups and of case-control type for one group. The main reasons for the exclusion of studies were insufficient quantitative information on WBV exposure and the lack of control groups. The findings of the selected studies and the results of the meta-analysis of both cross-sectional and cohort studies showed that occupational exposure to WBV is associated with an increased risk of LBP, sciatic pain, and degenerative changes in the spinal system, including lumbar intervertebral disc disorders. Owing to the cross-sectional design of the majority of the reviewed studies, this epidemiologic evidence is not sufficient to outline a clear exposure-response relationship between WBV exposure and LBP disorders. Upon comparing the epidemiological studies included in this review with those conducted before 1986, it is concluded that research design and the quality of exposure and health effect data in the field of WBV have improved in the last decade.

  17. The ISO standard: Guide for the evaluation of human exposure to whole-body vibration

    NASA Technical Reports Server (NTRS)

    Vongierke, H. E.

    1975-01-01

    The international guideline is discussed in terms of safety and human tolerance. Charts for equal subjective vibration intensity, subjective judgement of equal fatigue, and severe discomfort boundaries are included.

  18. An innovative multi dof TMD system for motorcycle handlebars designed to reduce structural vibrations and human exposure

    NASA Astrophysics Data System (ADS)

    Agostoni, S.; Cheli, F.; Leo, E.; Pezzola, M.

    2012-08-01

    Motor vehicle ride comfort is mainly affected by reciprocating engine inertia unbalances. These forces are transmitted to the driver through the main frame, the engine mounts, and the auxiliary sub systems—all components with which he physically comes into contact. On-road traction vehicle engines are mainly characterized by transient exercise. Thus, an excitation frequency range from 800 RPM (≈15 Hz for stationary vehicles) up to 15,000 RPM (≈250 Hz as a cut off condition) occurs. Several structural resonances are induced by the unbalancing forces spectrum, thus exposing the driver to amplified vibrations. The aim of this research is to reduce driver vibration exposure, by acting on the modal response of structures with which the driver comes into contact. An experimental methodology, capable of identifying local vibration modes was developed. The application of this methodology on a reference vehicle allows us to detect if/when/how the above mentioned resonances are excited. Numerical models were used to study structural modifications. In this article, a handlebar equipped with an innovative multi reciprocating tuned mass damper was optimized. All structural modifications were designed, developed and installed on a vehicle. Modal investigations were then performed in order to predict modification efficiency. Furthermore, functional solution efficiency was verified during sweep tests performed on a target vehicle, by means of a roller bench capable of replicating on-road loads. Three main investigation zones of the vehicle were detected and monitored using accelerometers: (1) engine mounts, to characterize vibration emissions; (2) bindings connecting the engine to the frame, in order to detect vibration transfer paths, with particular attention being paid to local dynamic amplifications due to compliances and (3) the terminal components with which the driver comes into contact.

  19. Effects of muscular strength, exercise order, and acute whole-body vibration exposure on bat swing speed.

    PubMed

    Reyes, G F Cisco; Dickin, D Clark; Dolny, Dennis G; Crusat, Nolan J K

    2010-12-01

    The purposes for this study were to investigate effects of acute whole-body vibration (WBV) exposure and exercise order on bat speed and to examine relationship between muscular strength and bat speed. All participants were recreationally trained men (n = 16; 22 ± 2 years; 181.4 ± 7.4 cm; 84.7 ± 9 kg), with previous baseball experience and were tested for 1 repetitive maximum (1RM) strength in squat and bench press. Subjects then participated in 4 randomized sessions on separate days, each consisting of 3 sets of 5 bat swings. Exercises (upper and lower body dynamic and static movements related to bat swing) with or without WBV exposure were performed after sets 1 and 2. Trials were as follows: no-exercise Control (CTRL), upper body followed by lower body exercises without WBV (Arm-Leg NOVIB), upper body followed by lower body exercises with WBV (Arm-Leg VIB), and lower body followed by upper body exercises with WBV (Leg-Arm VIB). Bat speed was recorded during each swing and averaged across sets. Statistical analyses were performed to assess differences across sets and trials. Linear regressions analyzed relationship between strength and bat speed. A significant relationship existed between bat speed and lower body strength (r = 0.406, p = 0.008) but not for upper body strength. The exercise order of Arm-Leg VIB significantly increased bat speed by 2.6% (p = 0.02). Performing identical order of exercises without vibration (Arm-Leg NOVIB) significantly decreased bat speed by 2% (p = 0.039). It was concluded that adding vibration exposure to total-body exercises can provide acute enhancements in bat speed. Additionally, leg strength was shown to influence bat speed suggesting that increasing leg strength may enhance bat speed. PMID:21088545

  20. Effects of muscular strength, exercise order, and acute whole-body vibration exposure on bat swing speed.

    PubMed

    Reyes, G F Cisco; Dickin, D Clark; Dolny, Dennis G; Crusat, Nolan J K

    2010-12-01

    The purposes for this study were to investigate effects of acute whole-body vibration (WBV) exposure and exercise order on bat speed and to examine relationship between muscular strength and bat speed. All participants were recreationally trained men (n = 16; 22 ± 2 years; 181.4 ± 7.4 cm; 84.7 ± 9 kg), with previous baseball experience and were tested for 1 repetitive maximum (1RM) strength in squat and bench press. Subjects then participated in 4 randomized sessions on separate days, each consisting of 3 sets of 5 bat swings. Exercises (upper and lower body dynamic and static movements related to bat swing) with or without WBV exposure were performed after sets 1 and 2. Trials were as follows: no-exercise Control (CTRL), upper body followed by lower body exercises without WBV (Arm-Leg NOVIB), upper body followed by lower body exercises with WBV (Arm-Leg VIB), and lower body followed by upper body exercises with WBV (Leg-Arm VIB). Bat speed was recorded during each swing and averaged across sets. Statistical analyses were performed to assess differences across sets and trials. Linear regressions analyzed relationship between strength and bat speed. A significant relationship existed between bat speed and lower body strength (r = 0.406, p = 0.008) but not for upper body strength. The exercise order of Arm-Leg VIB significantly increased bat speed by 2.6% (p = 0.02). Performing identical order of exercises without vibration (Arm-Leg NOVIB) significantly decreased bat speed by 2% (p = 0.039). It was concluded that adding vibration exposure to total-body exercises can provide acute enhancements in bat speed. Additionally, leg strength was shown to influence bat speed suggesting that increasing leg strength may enhance bat speed.

  1. Modeling of Spinal Column of Seated Human Body under Exposure to Whole-Body Vibration

    NASA Astrophysics Data System (ADS)

    Tamaoki, Gen; Yoshimura, Takuya; Kuriyama, Kaoru; Nakai, Kazuma

    In vehicle systems occupational drivers might expose themselves to vibration for a long time. This may cause illness of the spinal column such as low back pain. Therefore, it is necessary to evaluate the influence of vibration to the spinal column. Thus the modeling of seated human body is conducted in order to evaluate the effect of whole-body vibration to the spinal column. This model has the spinal column and the support structures such as the muscles of the back and the abdomen. The spinal column is made by the vertebrae and the intervertebral disks that are considered the rigid body and the rotational spring and damper respectively. The parameter of this model is decided by the literature and the body type of the subject with respect to the mass and the model structure. And stiffness and damping parameters are searched by fitting the model simulation results to the experimental measured data with respect to the vibration transmissibilities from the seat surface to the spinal column and the head and with respect to the driving-point apparent mass. In addition, the natural modes of the model compare with the result of experimental modal analysis. The influence of the abdomen and the muscles of the back are investigated by comparing three models with respect to above vibration characteristics. Three model are the proposed model, the model that has the spinal column and the model that has the muscles of the back in addition to the spinal column.

  2. The impact of self-reported exposure to whole-body-vibrations on the risk of disability pension among men: a 15 year prospective study

    PubMed Central

    2010-01-01

    Background Whole-body-vibrations are often associated with adverse health effect but the long term effects are less known. This study investigates the association between occupational exposures to whole-body vibrations, and subsequent transition to disability pension. Methods A total of 4215 male employees were followed up for subsequent disability pension retirement. Exposure to whole-body-vibration was self-reported while new cases of disability pension were retrieved from a national register. Results The hazard ratio (HR) for disability pension retirement among men exposed to whole-body-vibrations was 1.61 (95% confidence interval (CI) 1.07-2.40) after adjustment for age, smoking habits, BMI, physical job demands and awkward work postures. In our model, with the available explanatory variables, 5.6% of the male disability pension cases were attributable to whole-body-vibrations. Conclusions Exposure to whole-body-vibrations predicts subsequent disability pension retirement. Continued reduction of whole-body-vibrations may reduce the number of new cases of disability pension. PMID:20525268

  3. Measurement of whole-body vibration exposure from speed control humps

    NASA Astrophysics Data System (ADS)

    Khorshid, E.; Alkalby, F.; Kamal, H.

    2007-07-01

    The main objective of speed control humps is to introduce shocks and high vibration levels when a car passes over them if its speed is higher than the allowable limit. Hump geometry is a major factor in altering the level of these shocks and specifying the speed limit. However, there is no study of the relationship between whole body vibration due to passing over a speed control hump and lower back pain or occupational diseases. In this study, an experimental investigation is conducted to evaluate health risks associated with different geometry speed control humps. Vibration levels and shocks are measured by a seat pad accelerometer placed under the driver's seat to evaluate hazard risks on the human body's lower back. The assessment is based on two standard methods of measuring whole body vibration: the British standard BS 6841 and the new ISO/DIS standard 2631-5. These methods are used to assess the effects of vehicle type, passenger location in the vehicle, vehicle speed, and speed control hump geometry. It was found that circular speed control humps currently installed on many public roads should be modified in order to eliminate hazards. Two newly designed speed humps were proved to be less hazardous than circular speed control humps.

  4. a Field Survey on Effects of Exposure to Noise and Vibration from Railway Traffic, Part i: Annoyance and Activity Disturbance Effects

    NASA Astrophysics Data System (ADS)

    Öhrström, E.; Skånberg, A.-B.

    1996-05-01

    The paper presents some of the results from field investigations on effects of exposure to noise and vibration from railway traffic. Effects on annoyance, sleep disturbances and psycho-social well-being, as well as disturbance of different activities, were evaluated by a postal questionnaire. Effects on sleep and psycho-social well-being will be presented in a second paper. Fifteen different sites located near railway lines in Sweden were investigated. The study covered areas with different number of trains per 24 hours in areas with strong vibration exceeding 2 mm/s, caused by the railway traffic, as measured in the buildings, as well as areas without vibration, or with vibration weaker than 1 mm/s; 2833 persons between 18 and 75 years of age participated in the study. The results show that railway noise is experienced as more annoying in areas in which there is simultaneous exposure to vibration from railway traffic. Disturbance of communication was the most frequently mentioned annoyance reaction, outside and inside the dwellings, especially in areas with a high number of trains per 24 hours. To ensure an acceptable environmental quality where less than 5% of the exposed population is rather or very annoyed by railway noise, these noise levels must be below 80 dB LAmaxand below 55 Leqrespectively in areas without vibration. In areas with simultaneous exposure to strong vibration, actions against vibration or a greater distance between the houses and the railway line is needed, corresponding to a 10 dB(A) lower noise level than in areas without vibration.

  5. Hearing threshold and heart rate in men after repeated exposure to dynamic muscle work, sinusoidal vs stochastic whole body vibration and stable broadband noise.

    PubMed

    Manninen, O

    1984-01-01

    Changes in the temporary hearing threshold ( TTS2 ) and heart rate (HR) were examined in subjects exposed to stable noise, whole body vibration and dynamic muscular work at a dry-bulb temperature of 30 degrees C. The exposure combinations consisted of three categories of dynamic muscular work with varying loads ( 2W , 4W , 8W ), of two categories of noise and of three categories of vibration. The noise categories were: (1) no noise, and (2) stable, broadband (bandwidth 0.2-16.0 kHz) A-weighted noise with an intensity of 90 dB. The vibration categories were: (1) no vibration, (2) sinusoidal whole body vibration (Z-axis) with a frequency of 5 Hz, and (3) stochastic broadband (bandwidth 2.8-11.2 Hz) whole body vibration. A single test consisted of a control period of 30 min, three consecutive exposure periods of 16 min, each followed by a 4-min post-exposure interval and a recovery period of 15 min. The results of the variance analyses indicated that noise had the most notable effect on the TTS2 values at the hearing frequencies of both 4 and 6 kHz. Of the paired combinations, noise plus vibration and noise plus dynamic muscular work caused the most obvious combined effects. The combined effect of all three factors (noise, vibration and work) on the TTS2 values after three consecutive exposure periods was significant at the 2.5% level at the 4 kHz hearing frequency and at the 5% level at the 6 kHz hearing frequency. The added effect of vibration on enhanced TTS2 values was particularly clear when the vibration was stochastic and when the subjects had a low ( 2W ) working efficiency. Increasing the working efficiency, on the other hand, seemed to retard increases in the hearing threshold. Thus TTS2 values seemed to reflect the changes in HR values. It is as if the low rate of cardiovascular activity during light dynamic muscular work had enabled the manifestation of the cardiovascular effects of noise and vibration; during strenuous dynamic muscular work, however, the

  6. Influence of forest machine function on operator exposure to whole-body vibration in a cut-to-length timber harvester.

    PubMed

    Sherwin, L M; Owende, P M O; Kanali, C L; Lyons, J; Ward, S M

    2004-09-15

    The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25-0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms(-2) occurred at 5 and 3.2 Hz respectively. PMID:15370853

  7. Exposure to Sound Vibrations Lead to Transcriptomic, Proteomic and Hormonal Changes in Arabidopsis

    PubMed Central

    Ghosh, Ritesh; Mishra, Ratnesh Chandra; Choi, Bosung; Kwon, Young Sang; Bae, Dong Won; Park, Soo-Chul; Jeong, Mi-Jeong; Bae, Hanhong

    2016-01-01

    Sound vibration (SV) is considered as an external mechanical force that modulates plant growth and development like other mechanical stimuli (e.g., wind, rain, touch and vibration). A number of previous and recent studies reported developmental responses in plants tailored against SV of varied frequencies. This strongly suggests the existence of sophisticated molecular mechanisms for SV perception and signal transduction. Despite this there exists a huge gap in our understanding regarding the SV-mediated molecular alterations, which is a prerequisite to gain insight into SV-mediated plant development. Herein, we investigated the global gene expression changes in Arabidopsis thaliana upon treatment with five different single frequencies of SV at constant amplitude for 1 h. As a next step, we also studied the SV-mediated proteomic changes in Arabidopsis. Data suggested that like other stimuli, SV also activated signature cellular events, for example, scavenging of reactive oxygen species (ROS), alteration of primary metabolism, and hormonal signaling. Phytohormonal analysis indicated that SV-mediated responses were, in part, modulated by specific alterations in phytohormone levels; especially salicylic acid (SA). Notably, several touch regulated genes were also up-regulated by SV treatment suggesting a possible molecular crosstalk among the two mechanical stimuli, sound and touch. Overall, these results provide a molecular basis to SV triggered global transcriptomic, proteomic and hormonal changes in plant. PMID:27665921

  8. Exposure to mobile phone electromagnetic field radiation, ringtone and vibration affects anxiety-like behaviour and oxidative stress biomarkers in albino wistar rats.

    PubMed

    Shehu, Abubakar; Mohammed, Aliyu; Magaji, Rabiu Abdussalam; Muhammad, Mustapha Shehu

    2016-04-01

    Research on the effects of Mobile phone radio frequency emissions on biological systems has been focused on noise and vibrations as auditory stressors. This study investigated the potential effects of exposure to mobile phone electromagnetic field radiation, ringtone and vibration on anxiety-like behaviour and oxidative stress biomarkers in albino wistar rats. Twenty five male wistar rats were randomly divided into five groups of 5 animals each: group I: exposed to mobile phone in switched off mode (control), group II: exposed to mobile phone in silent mode, group III: exposed to mobile phone in vibration mode, group IV: exposed to mobile phone in ringtone mode, group V: exposed to mobile phone in vibration and ringtone mode. The animals in group II to V were exposed to 10 min call (30 missed calls for 20 s each) per day for 4 weeks. Neurobehavioural studies for assessing anxiety were carried out 24 h after the last exposure and the animals were sacrificed. Brain samples were collected for biochemical evaluation immediately. Results obtained showed a significant decrease (P < 0.05) in open arm duration in all the experimental groups when compared to the control. A significant decrease (P < 0.05) was also observed in catalase activity in group IV and V when compared to the control. In conclusion, the results of the present study indicates that 4 weeks exposure to electromagnetic radiation, vibration, ringtone or both produced a significant effect on anxiety-like behavior and oxidative stress in young wistar rats.

  9. Is Ionizing Radiation Harmful at any Exposure? An Echo That Continues to Vibrate.

    PubMed

    Azzam, Edouard I; Colangelo, Nicholas W; Domogauer, Jason D; Sharma, Neha; de Toledo, Sonia M

    2016-03-01

    The health risks to humans and non-human biota exposed to low dose ionizing radiation remain ambiguous and are the subject of intense debate. The need to establish risk assessment standards based on the mechanisms underlying low-level radiation exposure has been recognized by regulatory agencies as critical to adequately protect people and to make the most effective use of national resources. Here, the authors briefly review evidence showing that the molecular and biochemical changes induced by low doses of radiation differ from those induced by high doses. In particular, an array of redundant and inter-related mechanisms act in both prokaryotes and eukaryotes to restore DNA integrity following exposures to relatively low doses of sparsely ionizing radiation. Furthermore, the radiation-induced protective mechanisms often overcompensate and minimize the mutagenic potential of the byproducts of normal oxidative metabolism. In contrast to adaptive protection observed at low doses of sparsely ionizing radiation, there is evidence that even a single nuclear traversal by a densely ionizing particle track can trigger harmful effects that spread beyond the traversed cell and induce damaging effects in the nearby bystander cells. In vivo studies examining whether exposure to low dose radiation at younger age modulates the latency of expression of age-related diseases such as cancer, together with studies on the role of genetic susceptibility, will further illuminate the magnitude of risk of exposure to low dose radiation. PMID:26808874

  10. Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

    SciTech Connect

    Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

    2009-11-13

    Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

  11. The development of an intervention programme to reduce whole-body vibration exposure at work induced by a change in behaviour: a study protocol

    PubMed Central

    Tiemessen, Ivo JH; Hulshof, Carel TJ; Frings-Dresen, Monique HW

    2007-01-01

    Background Whole body vibration (WBV) exposure at work is common and studies found evidence that this exposure might cause low back pain (LBP). A recent review concluded there is a lack of evidence of effective strategies to reduce WBV exposure. Most research in this field is focussed on the technical implications, although changing behaviour towards WBV exposure might be promising as well. Therefore, we developed an intervention programme to reduce WBV exposure in a population of drivers with the emphasis on a change in behaviour of driver and employer. The hypothesis is that an effective reduction in WBV exposure, in time, will lead to a reduction in LBP as WBV exposure is a proxy for an increased risk of LBP. Methods/Design The intervention programme was developed specifically for the drivers of vibrating vehicles and their employers. The intervention programme will be based on the most important determinants of WBV exposure as track conditions, driving speed, quality of the seat, etc. By increasing knowledge and skills towards changing these determinants, the attitude, social influence and self-efficacy (ASE) of both drivers and employers will be affected having an effect on the level of exposure. We used the well-known ASE model to develop an intervention programme aiming at a change or the intention to change behaviour towards WBV exposure. The developed programme consists of: individual health surveillance, an information brochure, an informative presentation and a report of the performed field measurements. Discussion The study protocol described is advantageous as the intervention program actively tries to change behaviour towards WBV exposure. The near future will show if this intervention program is effective by showing a decrease in WBV exposure. PMID:18005400

  12. Cardiovascular changes and hearing threshold shifts in men under complex exposures to noise, whole body vibrations, temperatures and competition-type psychic load.

    PubMed

    Manninen, O

    1985-01-01

    This study deals with changes in the temporary hearing threshold (TTS2), heart rate (HR), R-wave amplitude (RWA), diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP) and reaction time (RT) in subjects (n = 108) who, while working on a choice reaction apparatus, were exposed in an exposure chamber to combinations of noise and vibration at dry bulb temperatures of 20 degrees and 30 degrees C. The study was carried out as a type 2-3-3 factorial experiment, the number of the exposure combinations thus being 18. To find out the effects of competition-type psychic stress, some of the subjects were placed in a competitive group and some in a non-competitive group. The members of the competitive group were given financial encouragement and information on their progress during the test, whereas those in the non-competitive group worked at the rate they considered best without any monetary rewards or interim information. The noise classes were: no noise, a stable broadband (bandwidth 0.2-16.0 kHz) A-weighted noise of 90 dB not related to competition, and a stable broadband A-weighted noise of 90 dB related to competition about the fastest reaction time. The vibration classes were: no vibration, sinusoidal whole body vibration (Z-axis) at a frequency of 5 Hz, and stochastic broadband (bandwidth 2.8-11.2 Hz) whole body vibration (Z-axis). The acceleration (rms) of both vibrations was 2.12 m/s2. One experiment consisted of a control period of 30 min, three consecutive exposure periods of 16 min with an interval of 4 min, and a 15-min recovery period. The variance analysis model best explained the variation in TTS2 values at 4 kHz and second best the variation in TTS2 values at 6 kHz; it explained the variation in HR values third best, the variation in SBP values fourth best and the variation in PP values fifth best. On the other hand, the model explained least well the variation in DBP and RWA values. In general, the explanatory power of the model

  13. Assessing combined exposures of whole-body vibration and awkward posture--further results from application of a simultaneous field measurement methodology.

    PubMed

    Raffler, Nastaran; Hermanns, Ingo; Sayn, Detlef; Göres, Benno; Ellegast, Rolf; Rissler, Jörg

    2010-01-01

    The drivers of ten vehicles (tram, helicopter, saloon car, van, forklift, two mobile excavators, wheel loader, tractor, elevating platform truck) were studied with regard to the combined exposures of whole-body vibration and awkward posture during occupational tasks. Seven degrees of freedom (DOFs), or body angles, were recorded as a function of time by means of the CUELA measuring system (Computer-assisted registration and long-term analysis of musculoskeletal workloads) for the purpose of posture assessment. The vibrational exposure is expressed as the vector sum of the frequency-weighted accelerations in the three Cartesian coordinates; these were recorded simultaneously with the posture measurement. Based upon the percentage of working time spent under different workloads, a scheme is proposed for classification of the two exposures into three categories. In addition, a risk of adverse health effects classified as low, possible or high can be assigned to the combination of the two exposures. With regard to posture, the most severe exposure was measured for the drivers of the wheel loader and for the tractor driver, whereas the lowest exposure was measured for the helicopter pilots and van drivers. With regard to the combination of whole-body and posture exposures, the tractor driver and the elevating platform truck driver exhibited the highest workloads.

  14. Assessing combined exposures of whole-body vibration and awkward posture--further results from application of a simultaneous field measurement methodology.

    PubMed

    Raffler, Nastaran; Hermanns, Ingo; Sayn, Detlef; Göres, Benno; Ellegast, Rolf; Rissler, Jörg

    2010-01-01

    The drivers of ten vehicles (tram, helicopter, saloon car, van, forklift, two mobile excavators, wheel loader, tractor, elevating platform truck) were studied with regard to the combined exposures of whole-body vibration and awkward posture during occupational tasks. Seven degrees of freedom (DOFs), or body angles, were recorded as a function of time by means of the CUELA measuring system (Computer-assisted registration and long-term analysis of musculoskeletal workloads) for the purpose of posture assessment. The vibrational exposure is expressed as the vector sum of the frequency-weighted accelerations in the three Cartesian coordinates; these were recorded simultaneously with the posture measurement. Based upon the percentage of working time spent under different workloads, a scheme is proposed for classification of the two exposures into three categories. In addition, a risk of adverse health effects classified as low, possible or high can be assigned to the combination of the two exposures. With regard to posture, the most severe exposure was measured for the drivers of the wheel loader and for the tractor driver, whereas the lowest exposure was measured for the helicopter pilots and van drivers. With regard to the combination of whole-body and posture exposures, the tractor driver and the elevating platform truck driver exhibited the highest workloads. PMID:20953080

  15. Random Vibrations

    NASA Technical Reports Server (NTRS)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  16. Mathematical equations and system identification models for a portable pneumatic bladder system designed to reduce human exposure to whole body shock and vibration

    NASA Astrophysics Data System (ADS)

    Aziz Ayyad, Ezzat

    A mathematical representation is sought to model the behavior of a portable pneumatic foam bladder designed to mitigate the effects of human exposure to shock and whole body random vibration. Fluid Dynamics principles are used to derive the analytic differential equations used for the physical equations Model. Additionally, combination of Wiener and Hammerstein block oriented representation techniques have been selected to create system identification (SID) block oriented models. A number of algorithms have been iterated to obtain numerical solutions for the system of equations which was found to be coupled and non-linear, with no analytic closed form solution. The purpose is to be able to predict the response of such system due to random vibrations and shock within reasonable margin of error. The constructed models were found to be accurate within accepted confidence level. Beside the analytic set of physical equations model representation, a linear SID model was selected to take advantage of the available vast amount of mathematical tools available to further analyze and redesign the bladder as a dynamic system. Measured field-test and lab test data have been collected from several helicopter and land terrain vehicle experiments. Numerous excitation and response acceleration measurement records were collected and used to prove the agreement with predictions. The estimation of two selected models were later applied to standard metrics in the frequency domain realization and compared with measurement responses. The collected test records are obtained from measured data at the US Army fields and facilities and at UNLV-CMEST environmental lab. The emerged models have been validated for conformity with actual accelerometer measurement responses and found within accepted error tolerance that is in both time and frequency domains. Further, standard metrics have been used to further confirm the confidence in the validation results. When comparing model prediction with

  17. Ride quality and international standard ISO 2631 (Guide for the evaluation of human exposure to whole-body vibration)

    NASA Technical Reports Server (NTRS)

    Allen, G. R.

    1975-01-01

    The evolution of the standard, which is aimed at promoting research and production of more data, and providing some design guidance, is outlined and its contents summarized. Some of the assumptions and information on which it is based are analyzed. Its application to vehicle ride quality is considered in the context of the safety, efficiency and comfort of crew and passengers. The importance of establishing the precise criteria against which vibration limits are required is underlined, particularly the difficulties of first defining comfort and then postulating appropriate levels. Some current and future work related to improving the standard is outlined and additional suggestions offered.

  18. Parallel β-sheet vibration band increases with proteins dipole moment under exposure to 1765 MHz microwaves.

    PubMed

    Calabrò, Emanuele; Magazù, Salvatore

    2016-02-01

    Effects of exposure of 4 h to mobile phones microwaves at 1765 MHz at a power density around 940 mW/m(2) on four typical proteins (hemoglobin in H2 O solution, and myoglobin, bovine serum albumin, and lysozyme in D2 O solution) were studied by means of Fourier Transform Infrared spectroscopy and Fourier self-deconvolution analysis. Increase in intensity of parallel β-sheet component around 1635 cm(-1) was observed after exposure of hemoglobin, myoglobin, and bovine serum albumin, showing that a mechanism of unfolding occurred after exposure, whereas no appreciable change in the amide I region occurred after lysozyme exposure. In addition, a relationship between protein dipole moment and protein unfolding rate was demonstrated with a correlation coefficient r = 0.973 and 95% confidence interval.

  19. Modelling the effects of exposure to whole-body vibration on low-back pain and its long-term consequences for sickness absence and associated work disability

    NASA Astrophysics Data System (ADS)

    Burdorf, A.; Hulshof, C. T. J.

    2006-12-01

    BackgroundExposure to whole-body vibration (WBV) is a well-known risk factor for the occurrence of low-back pain (LBP). Little is known about the long-term course of back pain in workers exposed to WBV and the consequences for (temporary) disability, due to lack of cohort studies with sufficiently long follow-up periods. MethodsA systematic review of the literature was performed to assess associations between exposure to WBV and LBP, sickness absence due to low-back disorders and permanent disability. A meta-analysis was used to estimate the prevalences of LBP and sickness absence due to low-back disorders in occupational populations, depending on relevant exposure characteristics. These prevalences were converted into probabilities for transitions between no complaints, LBP, sickness due to LBP, and disability. A Markov model was applied to evaluate a hypothetical cohort of workers without LBP at the start of the cohort and a follow-up of 40 years (40 cycles of 1 year) to reflect a long-life career with continuous exposure to WBV. ResultsIn this hypothetical cohort it was estimated that among workers with the highest exposure to WBV on average about 47 weeks of their working life were lost due to sick leave because of LBP, which is approximately 2.5% of their working life. When all workers on prolonged sick leave for 52 weeks would remain disabled for the rest of their working life, a maximum of 23.4% of their working life could be lost due to high WBV exposure. Among workers without or low exposure to WBV the corresponding losses were 0.8% and 7.8%, respectively. ConclusionThe approach to assess years of work lost due to an occupational exposure may provide a more adequate description for stakeholders than the traditional measures of relative risk or attributable risk fraction. The concept of work years lost may also facilitate a better appreciation of the potential benefits of preventive measures.

  20. Vibration manual

    NASA Technical Reports Server (NTRS)

    Green, C.

    1971-01-01

    Guidelines of the methods and applications used in vibration technology at the MSFC are presented. The purpose of the guidelines is to provide a practical tool for coordination and understanding between industry and government groups concerned with vibration of systems and equipments. Topics covered include measuring, reducing, analyzing, and methods for obtaining simulated environments and formulating vibration specifications. Methods for vibration and shock testing, theoretical aspects of data processing, vibration response analysis, and techniques of designing for vibration are also presented.

  1. Brief daily exposure to low-intensity vibration mitigates the degradation of the intervertebral disc in a frequency-specific manner

    PubMed Central

    Holguin, Nilsson; Uzer, Gunes; Chiang, Fu-Pen; Rubin, Clinton

    2011-01-01

    Hindlimb unloading of the rat causes rapid hypotrophy of the intervertebral disc (IVD) as well as reduced IVD height and glycosaminoglycan content. Here we tested the hypothesis that low-intensity mechanical vibrations (0.2 g), as a surrogate for exercise, will mitigate this degradation. Four groups of Sprague-Dawley rats (4.5 mo, n = 11/group) were hindlimb unloaded (HU) for 4 wk. In two of the HU groups, unloading was interrupted for 15 min/day by placing rats in an upright posture on a platform that was vertically oscillating at 45 or 90 Hz (HU+45, HU+90). Sham control rats stood upright on an inactive plate for 15 min/day (HU+SC). These three experimental groups were compared with HU uninterrupted by weightbearing (HU) and to normally ambulating age-matched controls. In the HU and HU+SC rats, 4 wk of unloading resulted in a 10% smaller IVD height, as well as less glycosaminoglycan in the whole IVD (7%) and nucleus pulposus (17%) and a greater collagen-to-glycosaminoglycan ratio in the whole IVD (17%). Brief daily exposure to 90 Hz mechanical oscillations mitigated this degradation; compared with HU ± SC, the IVD of HU+90 had an 8% larger height and greater glycosaminoglycan content in the whole IVD (12%) and nucleus pulposus (24%). In contrast, the 45 Hz signal failed to mitigate changes in height or glycosaminoglycan content brought with altered spinal loading, but normalized the collagen-to-glycosaminoglycan ratio to levels observed in age-matched controls. In summary, unloading caused marked phenotypic and biochemical changes in the IVD, a deterioration that was not slowed by brief weightbearing. However, low-intensity 90 Hz vibrations superimposed on weightbearing largely preserved the morphology and biochemistry of the IVD and suggest that these biomechanically based signals may help protect the IVD during long bouts of nonambulation. PMID:21960658

  2. Optimization approaches to ameliorate humidity and vibration related issues using the microAeth black carbon monitor for personal exposure measurement

    PubMed Central

    Cai, Jing; Yan, Beizhan; Kinney, Patrick L.; Perzanowski, Matthew S.; Jung, Kyung-Hwa; Li, Tiantian; Xiu, Guangli; Zhang, Danian; Olivo, Cosette; Ross, James; Miller, Rachel L.; Chillrud, Steven N.

    2014-01-01

    Exposure to ambient black carbon (BC) is associated with adverse health effects. Black carbon levels display large spatial and temporal variability in many settings, such as cities and rural households where fossil fuel and biomass, respectively, are commonly burned for transportation, heat and cooking. This paper addresses the optimization of the miniaturized personal BC monitor, the microAeth® for use in epidemiology studies. To address false positive and negative peaks in real time BC concentrations resulting from changes in temperature and humidity, an inlet with a diffusion drier was developed. In addition, we developed data cleaning algorithms to address occasional false positive and negative fluctuations in BC readings related to physical vibration, due in part to both dirt accumulations in the optical inserts and degraded components. These methods were successfully used to process real-time BC data generated from a cohort of 9-10 year old children (N= 54) in NYC, who wore 1 or 2 microAeth units for six 24hr time periods. Two hour and daily BC averages after data cleaning were consistent with averaged raw data (slopes near 1 with R =0.99, p<0.001; R= 0.95, p<0.001, respectively), strongly suggesting that the false positive and negative excursions balance each other out when averaged for at least 2 hrs. Data cleaning of identified suspect events allows more confidence in the interpretation of the real-time personal monitoring data generated in environmental exposure studies, with mean percent difference <10% for 19 duplicate deployments. PMID:25558122

  3. Whole-body Vibration Exposure of Drill Operators in Iron Ore Mines and Role of Machine-Related, Individual, and Rock-Related Factors

    PubMed Central

    Chaudhary, Dhanjee Kumar; Bhattacherjee, Ashis; Patra, Aditya Kumar; Chau, Nearkasen

    2015-01-01

    Background This study aimed to assess the whole-body vibration (WBV) exposure among large blast hole drill machine operators with regard to the International Organization for Standardization (ISO) recommended threshold values and its association with machine- and rock-related factors and workers' individual characteristics. Methods The study population included 28 drill machine operators who had worked in four opencast iron ore mines in eastern India. The study protocol comprised the following: measurements of WBV exposure [frequency weighted root mean square (RMS) acceleration (m/s2)], machine-related data (manufacturer of machine, age of machine, seat height, thickness, and rest height) collected from mine management offices, measurements of rock hardness, uniaxial compressive strength and density, and workers' characteristics via face-to-face interviews. Results More than 90% of the operators were exposed to a higher level WBV than the ISO upper limit and only 3.6% between the lower and upper limits, mainly in the vertical axis. Bivariate correlations revealed that potential predictors of total WBV exposure were: machine manufacturer (r = 0.453, p = 0.015), age of drill (r = 0.533, p = 0.003), and hardness of rock (r = 0.561, p = 0.002). The stepwise multiple regression model revealed that the potential predictors are age of operator (regression coefficient β = −0.052, standard error SE = 0.023), manufacturer (β = 1.093, SE = 0.227), rock hardness (β = 0.045, SE = 0.018), uniaxial compressive strength (β = 0.027, SE = 0.009), and density (β = –1.135, SE = 0.235). Conclusion Prevention should include using appropriate machines to handle rock hardness, rock uniaxial compressive strength and density, and seat improvement using ergonomic approaches such as including a suspension system. PMID:26929838

  4. Vibrational rainbows

    SciTech Connect

    Drolshagen, G.; Mayne, H.R.; Toennies, J.P.

    1981-07-01

    We extend the theory of inelastic rainbows to include vibrationally inelastic scattering, showing how the existence of vibrational rainbows can be deduced from collinear classical scattering theory. Exact close-coupling calculations are carried out for a breathing sphere potential, and rainbow structures are, in fact, observed. The location of the rainbows generally agrees well with the classical prediction. In addition, the sensitivity of the location of the rainbow to changes in the vibrational coupling has been investigated. It is shown that vibrational rainbows persist in the presence of anisotropy. Experimental results (R. David, M. Faubel, and J. P. Toennies, Chem. Phys. Lett. 18, 87 (1973)) are examined for evidence of vibrational rainbow structure, and it is shown that vibrational rainbow theory is not inconsistent with these results.

  5. Vibrational Coupling

    SciTech Connect

    2011-01-01

    By homing in on the distribution patterns of electrons around an atom, a team of scientists team with Berkeley Lab's Molecular Foundry showed how certain vibrations from benzene thiol cause electrical charge to "slosh" onto a gold surface (left), while others do not (right). The vibrations that cause this "sloshing" behavior yield a stronger SERS signal.

  6. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  7. Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations.

    PubMed

    Fattorini, L; Tirabasso, A; Lunghi, A; Di Giovanni, R; Sacco, F; Marchetti, E

    2016-02-01

    The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system.

  8. [Capillaroscopy in vibration disease].

    PubMed

    Vayssairat, M; Patri, B; Guilmot, J L; Housset, E; Dubrisay, J

    1982-10-23

    The results of nailfold capillary microscopy were compared in 107 lumberers who had been using a chain saw for more than 3 years and 115 manual workers who had never used vibrating tools. The prevalence of Raynaud's phenomenon was 61.7% in lumberers and 5.2% in the control group. The mean time of exposure to risk before the condition developed was 7.86 years. The syndrome was usually mild, but the patients had an abnormally high incidence of accidents at work, including wounds and cut off fingers. The number of capillary loops was significantly reduced. The lumberers affected showed an abnormal spasm of the digital artery in response to cold; the predictive value of this test was 88%. It is suggested that nailfold capillary microscopy should be systematically used in industrial medicine for monitoring workers using a vibrating tool.

  9. Vibration analyzer

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1990-01-01

    The invention relates to monitoring circuitry for the real time detection of vibrations of a predetermined frequency and which are greater than a predetermined magnitude. The circuitry produces an instability signal in response to such detection. The circuitry is particularly adapted for detecting instabilities in rocket thrusters, but may find application with other machines such as expensive rotating machinery, or turbines. The monitoring circuitry identifies when vibration signals are present having a predetermined frequency of a multi-frequency vibration signal which has an RMS energy level greater than a predetermined magnitude. It generates an instability signal only if such a vibration signal is identified. The circuitry includes a delay circuit which responds with an alarm signal only if the instability signal continues for a predetermined time period. When used with a rocket thruster, the alarm signal may be used to cut off the thruster if such thruster is being used in flight. If the circuitry is monitoring tests of the thruster, it generates signals to change the thruster operation, for example, from pulse mode to continuous firing to determine if the instability of the thruster is sustained once it is detected.

  10. Vibration safety limits for magnetic resonance elastography.

    PubMed

    Ehman, E C; Rossman, P J; Kruse, S A; Sahakian, A V; Glaser, K J

    2008-02-21

    Magnetic resonance elastography (MRE) has been demonstrated to have potential as a clinical tool for assessing the stiffness of tissue in vivo. An essential step in MRE is the generation of acoustic mechanical waves within a tissue via a coupled mechanical driver. Motivated by an increasing volume of human imaging trials using MRE, the objectives of this study were to audit the vibration amplitude of exposure for our IRB-approved human MRE studies, to compare these values to a conservative regulatory standard for vibrational exposure and to evaluate the applicability and implications of this standard for MRE. MRE displacement data were examined from 29 MRE exams, including the liver, brain, kidney, breast and skeletal muscle. Vibrational acceleration limits from a European Union directive limiting occupational exposure to whole-body and extremity vibrations (EU 2002/44/EC) were adjusted for time and frequency of exposure, converted to maximum displacement values and compared to the measured in vivo displacements. The results indicate that the vibrational amplitudes used in MRE studies are below the EU whole-body vibration limit, and the EU guidelines represent a useful standard that could be readily accepted by Institutional Review Boards to define standards for vibrational exposures for MRE studies in humans.

  11. Heat, cold, noise, and vibration

    SciTech Connect

    Horvath, S.M.; Bedi, J.F. )

    1990-03-01

    Exposure to a cold environment induces a number of physiological alterations, the most serious being hypothermia. This state can occur in all individuals, but the very young and the elderly are more susceptible. Environmental and industrially generated high ambient temperature can place further stress on aged individuals and workers, resulting in a complex symptom picture. Morbidity and death may result from such exposures. Causative factors have been identified. Noise exposure induces hearing losses above those secondary to the aging process. Psychophysiological effects during noise exposure are considered to result from the sympathetic activity secondary to a general stress reaction. Vibration from the use of power tools results in Raynaud's phenomenon. However, modification of power tools has reduced the symptoms associated with vibration exposure. Termination of exposure to vibration appears eventually to reduce symptoms related to white-finger spasms. Interaction between these stressors has not been clarified because of the complex effects of each. The need for additional information about the response to these stressors is evident. 38 references.

  12. Production, Delivery and Application of Vibration Energy in Healthcare

    NASA Astrophysics Data System (ADS)

    Abundo, Paolo; Trombetta, Chiara; Foti, Calogero; Rosato, Nicola

    2011-02-01

    In Rehabilitation Medicine therapeutic application of vibration energy in specific clinical treatments and in sport rehabilitation is being affirmed more and more.Vibration exposure can have positive or negative effects on the human body depending on the features and time of the characterizing wave. The human body is constantly subjected to different kinds of vibrations, inducing bones and muscles to actively modify their structure and metabolism in order to fulfill the required functions. Like every other machine, the body supports only certain vibration energy levels over which long term impairments can be recognized. As shown in literature anyway, short periods of vibration exposure and specific frequency values can determine positive adjustments.

  13. Good Vibrations

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A Small Business Innovation Research (SBIR) sponsorship from NASA's Dryden Flight Research Center, assisted MetroLaser, of Irvine, California, in the development of a self-aligned laser vibrometer system. VibroMet, capable of measuring surface vibrations in a variety of industries, provides information on the structural integrity and acoustical characteristics of manufactured products. This low-cost, easy-to-use sensor performs vibration measurement from distances of up to three meters without the need for adjustment. The laser beam is simply pointed at the target and the system then uses a compact laser diode to illuminate the surface and to subsequently analyze the reflected light. The motion of the surface results in a Doppler shift that is measured with very high precision. VibroMet is considered one of the many behind-the-scenes tools that can be relied on to assure the quality, reliability and safety of everything from airplane panels to disk brakes

  14. Human response to vibration stress in Japanese workers: lessons from our 35-year studies A narrative review

    PubMed Central

    MATOBA, Tsunetaka

    2015-01-01

    The occupational uses with vibratory tools or vehicles provoked health disorders of users. We reviewed narratively our articles of 35 yr studies and their related literatures, and considered the pathophysiology of the hand-arm vibration disorders. Concerning the risk factors of health impairments in workers with vibratory tools, there are two conflicting schools of the researchers: The peripheral school emphasizes that vibration only makes predominant impairments on hands and arms, showing typically Raynaud’s phenomenon in the fingers. In the systemic school, the health disorders are produced by combination with vibration, noise and working environment, namely vibratory work itself, leading to diversified symptoms and signs in relation to systemic impairments. Our 35 yr studies have evidently supported the systemic school, including disorders of the central and autonomic nervous systems. The genesis is vibratory work itself, including vibration, noise, cold working environment, ergonomic and biodynamic conditions, and emotional stress in work. Because the health disorders yield in the whole body, the following measures would contribute to the prevention of health impairments: the attenuation of vibration and noise generated form vibratory machines and the regulations on operating tool hours. In conclusion, this occupational disease results from systemic impairments due to long-term occupational work with vibratory tools. PMID:26460379

  15. Effect of higher frequency components and duration of vibration on bone tissue alterations in the rat-tail model

    PubMed Central

    PEELUKHANA, Srikara V.; GOENKA, Shilpi; KIM, Brian; KIM, Jay; BHATTACHARYA, Amit; STRINGER, Keith F.; BANERJEE, Rupak K.

    2015-01-01

    To formulate more accurate guidelines for musculoskeletal disorders (MSD) linked to Hand-Arm Vibration Syndrome (HAVS), delineation of the response of bone tissue under different frequencies and duration of vibration needs elucidation. Rat-tails were vibrated at 125 Hz (9 rats) and 250 Hz (9 rats), at 49 m/s2, for 1D (6 rats), 5D (6 rats) and 20D (6 rats); D=days (4 h/d). Rats in the control group (6 rats for the vibration groups; 2 each for 1D, 5D, and 20D) were left in their cages, without being subjected to any vibration. Structural and biochemical damages were quantified using empty lacunae count and nitrotyrosine signal-intensity, respectively. One-way repeated-measure mixed-model ANOVA at p<0.05 level of significance was used for analysis. In the cortical bone, structural damage quantified through empty lacunae count was significant (p<0.05) at 250 Hz (10.82 ± 0.66) in comparison to the control group (7.41 ± 0.76). The biochemical damage was significant (p<0.05) at both the 125 Hz and 250 Hz vibration frequencies. The structural damage was significant (p<0.05) at 5D for cortical bone while the trabecular bone showed significant (p<0.05) damage at 20D time point. Further, the biochemical damage increased with increase in the duration of vibration with a significant (p<0.05) damage observed at 20D time point and a near significant change (p=0.08) observed at 5D time point. Structural and biochemical changes in bone tissue are dependent upon higher vibration frequencies of 125 Hz, 250 Hz and the duration of vibration (5D, 20D). PMID:25843564

  16. Effect of higher frequency components and duration of vibration on bone tissue alterations in the rat-tail model.

    PubMed

    Peelukhana, Srikara V; Goenka, Shilpi; Kim, Brian; Kim, Jay; Bhattacharya, Amit; Stringer, Keith F; Banerjee, Rupak K

    2015-01-01

    To formulate more accurate guidelines for musculoskeletal disorders (MSD) linked to Hand-Arm Vibration Syndrome (HAVS), delineation of the response of bone tissue under different frequencies and duration of vibration needs elucidation. Rat-tails were vibrated at 125 Hz (9 rats) and 250 Hz (9 rats), at 49 m/s(2), for 1D (6 rats), 5D (6 rats) and 20D (6 rats); D=days (4 h/d). Rats in the control group (6 rats for the vibration groups; 2 each for 1D, 5D, and 20D) were left in their cages, without being subjected to any vibration. Structural and biochemical damages were quantified using empty lacunae count and nitrotyrosine signal-intensity, respectively. One-way repeated-measure mixed-model ANOVA at p<0.05 level of significance was used for analysis. In the cortical bone, structural damage quantified through empty lacunae count was significant (p<0.05) at 250 Hz (10.82 ± 0.66) in comparison to the control group (7.41 ± 0.76). The biochemical damage was significant (p<0.05) at both the 125 Hz and 250 Hz vibration frequencies. The structural damage was significant (p<0.05) at 5D for cortical bone while the trabecular bone showed significant (p<0.05) damage at 20D time point. Further, the biochemical damage increased with increase in the duration of vibration with a significant (p<0.05) damage observed at 20D time point and a near significant change (p=0.08) observed at 5D time point. Structural and biochemical changes in bone tissue are dependent upon higher vibration frequencies of 125 Hz, 250 Hz and the duration of vibration (5D, 20D).

  17. Inhalation exposure of animals.

    PubMed Central

    Phalen, R F

    1976-01-01

    Relative advantages and disadvantages and important design criteria for various exposure methods are presented. Five types of exposures are discussed: whole-body chambers, head-only exposures, nose or mouth-only methods, lung-only exposures, and partial-lung exposures. Design considerations covered include: air cleaning and conditioning; construction materials; losses of exposure materials; evenness of exposure; sampling biases; animal observation and care; noise and vibration control, safe exhausts, chamber loading, reliability, pressure fluctuations; neck seals, masks, animal restraint methods; and animal comfort. Ethical considerations in use of animals in inhalation experiments are also discussed. PMID:1017420

  18. Sensor design for outdoor racing bicycle field testing for human vibration comfort evaluation

    NASA Astrophysics Data System (ADS)

    Vanwalleghem, Joachim; De Baere, Ives; Loccufier, Mia; Van Paepegem, Wim

    2013-09-01

    This paper is concerned with the vibrational comfort evaluation of the cyclist when cycling a rough surface. Outdoor comfort tests have so far only been done through instrumenting the bicycle with accelerometers. This work instruments a racing bicycle with custom-made contact force sensors and velocity sensors to acquire human comfort through the absorbed power method. Comfort evaluation is assessed at the hand-arm and seat interface of the cyclist with the bicycle. By means of careful finite-element analysis for designing the force gauges at the handlebar and the seat combined with precise calibration of both force and velocity sensors, all sensors have proven to work properly. Initial field tests are focused on the proper functioning of the designed sensors and their suitability for vibration comfort measurements. Tests on a cobblestone road reveal that the outcome of the absorbed power values is within the same range as those from laboratory tests found in the literature. This sensor design approach for outdoor testing with racing bicycles may give a new interpretation on evaluating the cyclist's comfort since the vibrational load is not only quantified in terms of acceleration but also in terms of force and velocity at the bicycle-cyclist contact points.

  19. Rheumatic effects of vibration at work

    PubMed Central

    Palmer, Keith T; Bovenzi, Massimo

    2016-01-01

    Occupational exposures to vibration come in many guises and are very common at a population level. It follows that an important minority of working-aged patients seen by medical services will have been exposed to this hazard of employment. Vibration can cause human health effects which may manifest in the patients that rheumatologists see. In this chapter we identify the health effects of relevance to them, and review their epidemiology, pathophysiology, clinical presentation, differential diagnosis, and vocational and clinical management. On either side of this, we describe the nature and assessment of the hazard, the scale and common patterns of exposure to vibration in the community, and the legal basis for controlling health risks, and comment on the role of health surveillance in detecting early adverse effects and what can be done to prevent the rheumatic effects of vibration at work. PMID:26612239

  20. Rheumatic effects of vibration at work.

    PubMed

    Palmer, Keith T; Bovenzi, Massimo

    2015-06-01

    Occupational exposures to vibration come in many guises, and they are very common at a population level. It follows that an important minority of working-aged patients seen by medical services will have been exposed to this hazard of employment. Vibration can cause human health effects, which may manifest in the patients that rheumatologists see. In this chapter, we identify the health effects of relevance to them, and review their epidemiology, pathophysiology, clinical presentation, differential diagnosis and vocational and clinical management. On either side of this, we describe the nature and assessment of the hazard, the scale and common patterns of exposure to vibration in the community and the legal basis for controlling health risks, and we comment on the role of health surveillance in detecting early adverse effects and what can be done to prevent the rheumatic effects of vibration at work.

  1. Human comfort in relation to sinusoidal vibration

    NASA Technical Reports Server (NTRS)

    Jones, B.; Rao, B. K. N.

    1975-01-01

    An investigation was made to assess the overall subjective comfort levels to sinusoidal excitations over the range 1 to 19 Hz using a two axis electrohydraulic vibration simulator. Exposure durations of 16 minutes, 25 minutes, 1 hour, and 2.5 hours have been considered. Subjects were not exposed over such durations, but were instructed to estimate the overall comfort levels preferred had they been constantly subjected to vibration over such durations.

  2. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  3. Flow-induced vibration

    SciTech Connect

    Blevins, R.D.

    1990-01-01

    This book reports on dimensional analysis; ideal fluid models; vortex-induced vibration; galloping and flutter; instability of tube and cylinder arrays; vibrations induced by oscillating flow; vibration induced by turbulence and sound; damping of structures; sound induced by vortex shedding; vibrations of a pipe containing a fluid flow; indices. It covers the analysis of the vibrations of structures exposed to fluid flows; explores applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.

  4. [Vibration hazards in quarry workers].

    PubMed

    Sakakibara, H; Miyao, M; Nakagawa, T; Yamada, S; Kobayashi, F; Ono, Y; Iwata, M; Hisanaga, N; Momoi, N

    1984-03-01

    Vibration hazards were surveyed in a population of quarry workers using chipping hammers and to a lesser extent, rock drills. Sixty-nine male quarry workers, aged 49.1 +/- 8.7 and exposed to vibration for 16.4 +/- 5.1 years, were surveyed in 1981-82. They were exposed to vibration for about 2-4 hours per days, mainly under a piece-work pay system. They had a high prevalence of Raynaud's phenomenon (36.2%) and numbness in upper extremities (53.6%). It is considered that the high prevalence was mainly due to large vibration levels in chipping hammers and rock drills and long daily exposure time. The attacks of Raynaud's phenomenon were found predominantly in the left hand, which held chisels, whereas the restriction of motion in the elbow was predominantly in the right arm which pushed chipping hammers. The same 49 male quarry workers in this population were also surveyed in 1976-77 and the prevalence of their complaints between 1976-77 and 1981-82 was compared. The prevalence of Raynaud's phenomenon was the same, but the frequency of the attacks increased between the two periods. The prevalence of other complaints such as numbness, pain and chills in the upper extremities also increased. Between 1976-77 and 1981-82, the prevalence of Raynaud's phenomenon, numbness, and pain in the upper extremities increased in the population of quarriers exposed to vibration for above 2.6 hours per day and 200 days per year, or 600 hours per year. On the other hand, the prevalence of these complaints mostly decreased in the population of quarriers with less exposure.

  5. Effect of vibration duration on human discomfort. [passenger comfort and random vibration

    NASA Technical Reports Server (NTRS)

    Clevenson, S. A.; Dempsey, T. K.; Leatherwood, J. D.

    1978-01-01

    The duration effects of random vertical vibration on passenger discomfort were studied in a simulated section of an aircraft cabin configured to seat six persons in tourist-class style. Variables of the study included time of exposure (0.25 min to 60 min) and the rms amplitude of vibration (0.025g to 0.100g). The vibrations had a white noise spectrum with a bandwidth of 10 Hz centered at 5 Hz. Data indicate that the discomfort threshold occurred at an rms vertical acceleration level of 0.027g for all durations of vibration. However, for acceleration levels that exceeded the discomfort threshold, a systematic decrease in discomfort occurred as a function of increasing duration of vibration. For the range of accelerations used, the magnitude of the discomfort decrement was shown to be independent of acceleration level. The results suggest that discomfort from vertical vibration applied in the frequency range at which humans are most sensitive decreases with longer exposure, which is the opposite of the recommendation of the International Standard ISO 2631-1974 (E) Guide for the Evaluation of Human Exposure to Whole-Body Vibration.

  6. Vibrotactile temporary threshold shifts induced by hand-transmitted vibration during underwater work.

    PubMed

    Maeda, S; Yonekawa, Y; Kanada, K; Takahashi, Y; Griffin, M J

    1995-01-01

    The purpose of this paper is to clarify the temporary threshold shifts (TTS) of fingertip vibratory sensation produced by hand-transmitted vibration in an underwater work environment. The hand-transmitted vibration was applied with a pneumatic tool to the right hand of four experienced male SCUBA divers. The threshold of 125 Hz vibratory sensation was measured at the tip of the right forefinger before and after vibration exposure in the atmosphere and underwater. Vibration exposure at a 4 m depth produced greater TTS than in the atmosphere. The recovery time of TTS after vibration exposure in an underwater were affected by the underwater pressure.

  7. Assessment of vibration induced white finger: reliability and validity of two tests.

    PubMed

    Hack, M; Boillat, M A; Schweizer, C; Lob, M

    1986-04-01

    The reliability and validity of two tests (cold water and reactive hyperaemia) designed to confirm a patient's history of vibration induced white finger were studied. The cold water test is a measure of digital rewarming after hand immersion in cold water. Reactive hyperaemia consists of measuring digital rewarming after cold water immersion plus temporary ischaemia imposed on the hand. For ten weeks, ten healthy male volunteers were submitted once a week to both tests to study their reliability. The results showed a strong inter and intraindividual scattering. The mean value for the whole group, however, did not differ significantly from one week to the next. Fifty two subjects exposed to hand/arm vibration were submitted to both tests to estimate their validity. They were classified, according to their medical history, into three groups: A = no symptoms, B = tingling or numbess, or both, C = Raynaud's phenomenon. Both tests agreed with the clinical staging. For reactive hyperaemia, however, the differences between the groups were statistically significant only when the test was performed at 10 degrees C. These tests are more useful to study a group than an individual case. Time has no significant effect on the mean result of a group.

  8. Thermoregulatory responses to heat and vibration in men

    NASA Technical Reports Server (NTRS)

    Spaul, W. A.; Spear, R. C.; Greenleaf, J. E.

    1986-01-01

    The effect of vibration on thermoregulatory responses was studied in heat-acclimated men exposed suddenly to simultaneous heat and whole body vibrations (WBVs) at two intensity levels, each at graded frequencies between 5 and 80 Hz. The mean rectal temperature (Tre) became elevated more quickly in the WBV exposures than in the controls (heat exposure alone). Both intensity- and frequency-dependent WBV relationships were recorded in localized blood flows and in sweat rates. Thus, vibration appears to reduce the efficiency of the cooling mechanisms during a heat exposure.

  9. Significant characteristics of social response to noise and vibration

    NASA Technical Reports Server (NTRS)

    Nishinomiya, G.

    1979-01-01

    Several surveys made since 1971 to investigate annoyance resulting from noise and vibration, from various sources were studied in order to quantify the relation between annoyance response to noise or vibration and properties of the respondent including factors such as noise exposure, etc. Samples collected by the social surveys and physical measurements were analyzed by multi-dimensional analysis.

  10. Control System Damps Vibrations

    NASA Technical Reports Server (NTRS)

    Kopf, E. H., Jr.; Brown, T. K.; Marsh, E. L.

    1983-01-01

    New control system damps vibrations in rotating equipment with help of phase-locked-loop techniques. Vibrational modes are controlled by applying suitable currents to drive motor. Control signals are derived from sensors mounted on equipment.

  11. Hermetically sealed vibration damper

    NASA Technical Reports Server (NTRS)

    Wheatley, D. G.

    1969-01-01

    Simple fluidic vibration damper for installation at each pivotal mounting between gimbals isolates inertial measuring units from external vibration and other disruptive forces. Installation between each of the three gimbal axes can dampen vibration and shock in any direction while permitting free rotation of the gimbals.

  12. Vibration ride comfort criteria

    NASA Technical Reports Server (NTRS)

    Dempsey, T. K.; Leatherwood, J. D.

    1976-01-01

    Results are presented for an experimental study directed to derive equal vibration discomfort curves, to determine the influence of vibration masking in order to account for the total discomfort of any random vibration, and to develop a scale of total vibration discomfort in the case of human response to whole-body vertical vibration. Discomfort is referred to as a subjective discomfort associated with the acceleration level of a particular frequency band. It is shown that passenger discomfort to whole-body vibration increases linearly with acceleration level for each frequency. Empirical data provide a mechanism for determining the degree of masking (or summation) of the discomfort of multiple frequency vibration. A scale for the prediction of passenger discomfort is developed.

  13. Kappa Delta Award. Low back pain and whole body vibration.

    PubMed

    Pope, M H; Magnusson, M; Wilder, D G

    1998-09-01

    The investigators describe their multifaceted approach to the study of the relationship between whole body vibration and low back pain. The epidemiologic study was a two center study of drivers and sedentary workers in the United States and Sweden. The vibration exposure was measured in the vehicles. It was found that the career vibration exposure was related to low back, neck, and shoulder pain. However, disability was related to job satisfaction. In vivo experiments, using percutaneous pin mounted accelerometers have shown that the natural frequency is at 4.5 Hz. The frequency response is affected by posture, seating, and seat back inclination. The response appears to be determined largely by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration, should be reduced for those recovering from these problems. Vibration attenuating seats and correct ergonomic layout of the cabs may reduce the risks of recurrence. PMID:9755785

  14. The influence of vibration on seated human drowsiness

    PubMed Central

    AZIZAN, Amzar; FARD, Mohammad; AZARI, Michael F.; BENEDIKTSDÓTTIR, Bryndís; ARNARDÓTTIR, Erna Sif; JAZAR, Reza; MAEDA, Setsuo

    2016-01-01

    Although much is known about human body vibration discomfort, there is little research data on the effects of vibration on vehicle occupant drowsiness. A laboratory experimental setup has been developed. Vibration was applied to the volunteers sitting on the vehicle seat mounted on the vibration platform. Seated volunteers were exposed to a Gaussian random vibration, with 1–15 Hz frequency bandwidth at 0.2 ms−2 r.m.s., for 20-minutes. Two drowsiness measurement methods were used, Psychomotor Vigilance Test (PVT) and Karolinska Sleepiness Scale (KSS). Significant changes in PVT (p<0.05) and KSS (p<0.05) were detected in all eighteen volunteers. Furthermore, a moderate correlation (r>0.4) was observed between objective measurement (PVT) and subjective measurement (KSS). The results suggest that exposure to vibration even for 20-minutes can cause significant drowsiness impairing psychomotor performance. This finding has important implications for road safety. PMID:26829971

  15. Vibrating fuel grapple. [LMFBR

    DOEpatents

    Chertock, A.J.; Fox, J.N.; Weissinger, R.B.

    A reactor refueling method is described which utilizes a vibrating fuel grapple for removing spent fuel assemblies from a reactor core. It incorporates a pneumatic vibrator in the grapple head which allows additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

  16. Vibrating fuel grapple

    DOEpatents

    Chertock, deceased, Alan J.; Fox, Jack N.; Weissinger, Robert B.

    1982-01-01

    A reactor refueling method utilizing a vibrating fuel grapple for removing spent fuel assemblies from a reactor core which incorporates a pneumatic vibrator in the grapple head, enabling additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

  17. Dose-response patterns for vibration-induced white finger

    PubMed Central

    Griffin, M; Bovenzi, M; Nelson, C

    2003-01-01

    Aims: To investigate alternative relations between cumulative exposures to hand-transmitted vibration (taking account of vibration magnitude, lifetime exposure duration, and frequency of vibration) and the development of white finger (Raynaud's phenomenon). Methods: Three previous studies have been combined to provide a group of 1557 users of powered vibratory tools in seven occupational subgroups: stone grinders, stone carvers, quarry drillers, dockyard caulkers, dockyard boilermakers, dockyard painters, and forest workers. The estimated total operating duration in hours was thus obtained for each subject, for each tool, and for all tools combined. From the vibration magnitudes and exposure durations, seven alternative measurements of cumulative exposure were calculated for each subject, using expressions of the form: dose = ∑amiti, where ai is the acceleration magnitude on tool i, ti is the lifetime exposure duration for tool i, and m = 0, 1, 2, or 4. Results: For all seven alternative dose measures, an increase in dose was associated with a significant increase in the occurrence of vibration-induced white finger, after adjustment for age and smoking. However, dose measures with high powers of acceleration (m > 1) faired less well than measures in which the weighted or unweighted acceleration, and lifetime exposure duration, were given equal weight (m = 1). Dose determined solely by the lifetime exposure duration (without consideration of the vibration magnitude) gave better predictions than measures with m greater than unity. All measures of dose calculated from the unweighted acceleration gave better predictions than the equivalent dose measures using acceleration frequency-weighted according to current standards. Conclusions: Since the total duration of exposure does not discriminate between exposures accumulated over the day and those accumulated over years, a linear relation between vibration magnitude and exposure duration seems appropriate for predicting

  18. Force limited vibration testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry D.

    1991-01-01

    A new method of conducting lab vibration tests of spacecraft equipment was developed to more closely simulate the vibration environment experienced when the spacecraft is launched on a rocket. The improved tests are tailored to identify equipment design and workmanship problems without inducing artificial failures that would not have occurred at launch. These new, less destructive types of vibration tests are essential to JPL's protoflight test approach in which lab testing is conducted using the flight equipment, often one of a kind, to save time and money. In conventional vibration tests, only the input vibratory motion is specified; the feedback, or reaction force, between the test item and the vibration machine is ignored. Most test failures occur when the test item goes into resonance, and the reaction force becomes very large. It has long been recognized that the large reaction force is a test artifact which does not occur with the lightweight, flexible mounting structures characteristic of spacecraft and space vehicles. In new vibration tests, both the motion and the force provided to the test item by the vibration machine are controlled, so that the vibration ride experienced by the test item is as in flight.

  19. Vibrational Schroedinger Cats

    NASA Technical Reports Server (NTRS)

    Kis, Z.; Janszky, J.; Vinogradov, An. V.; Kobayashi, T.

    1996-01-01

    The optical Schroedinger cat states are simple realizations of quantum states having nonclassical features. It is shown that vibrational analogues of such states can be realized in an experiment of double pulse excitation of vibrionic transitions. To track the evolution of the vibrational wave packet we derive a non-unitary time evolution operator so that calculations are made in a quasi Heisenberg picture.

  20. Multiple direction vibration fixture

    DOEpatents

    Cericola, Fred; Doggett, James W.; Ernest, Terry L.; Priddy, Tommy G.

    1991-01-01

    An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

  1. Multiple direction vibration fixture

    SciTech Connect

    Cericola, F.; Doggett, J.W.; Ernest, T.L.

    1991-08-27

    An apparatus is discussed for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 {degrees} around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

  2. Multiple direction vibration fixture

    SciTech Connect

    Cericola, F.; Doggett, J.W.; Ernest, T.L.; Priddy, T.G.

    1990-03-21

    An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis. 1 fig.

  3. Vibrational Spectroscopy of Biomembranes

    NASA Astrophysics Data System (ADS)

    Schultz, Zachary D.; Levin, Ira W.

    2011-07-01

    Vibrational spectroscopy, commonly associated with IR absorption and Raman scattering, has provided a powerful approach for investigating interactions between biomolecules that make up cellular membranes. Because the IR and Raman signals arise from the intrinsic properties of these molecules, vibrational spectroscopy probes the delicate interactions that regulate biomembranes with minimal perturbation. Numerous innovative measurements, including nonlinear optical processes and confined bilayer assemblies, have provided new insights into membrane behavior. In this review, we highlight the use of vibrational spectroscopy to study lipid-lipid interactions. We also examine recent work in which vibrational measurements have been used to investigate the incorporation of peptides and proteins into lipid bilayers, and we discuss the interactions of small molecules and drugs with membrane structures. Emerging techniques and measurements on intact cellular membranes provide a prospective on the future of vibrational spectroscopic studies of biomembranes.

  4. Vibration control in accelerators

    SciTech Connect

    Montag, C.

    2011-01-01

    In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.

  5. Vibration Analysis and the Accelerometer

    ERIC Educational Resources Information Center

    Hammer, Paul

    2011-01-01

    Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…

  6. PREFACE: Vibrations at surfaces Vibrations at surfaces

    NASA Astrophysics Data System (ADS)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  7. NIF Ambient Vibration Measurements

    SciTech Connect

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  8. Quantification of the effects of audible rattle and source type on the human response to environmental vibration.

    PubMed

    Woodcock, J; Sica, G; Peris, E; Sharp, C; Moorhouse, A T; Waddington, D C

    2016-03-01

    The present research quantifies the influence of source type and the presence of audible vibration-induced rattle on annoyance caused by vibration in residential environments. The sources of vibration considered are railway and the construction of a light rail system. Data were measured in the United Kingdom using a socio-vibration survey (N = 1281). These data are analyzed using ordinal logit models to produce exposure-response relationships describing community annoyance as a function of vibration exposure. The influence of source type and the presence of audible vibration-induced rattle on annoyance are investigated using dummy variable analysis, and quantified using odds-ratios and community tolerance levels. It is concluded that the sample population is more likely to express higher levels of annoyance if the vibration source is construction compared to railway, and if vibration-induced rattle is audible. PMID:27036258

  9. 2008 Vibrational Spectroscopy

    SciTech Connect

    Philip J. Reid

    2009-09-21

    The conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and interfaces. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of systems.

  10. Vibration exercise makes your muscles and bones stronger: fact or fiction?

    PubMed

    Cardinale, Marco; Rittweger, Jörn

    2006-03-01

    Vibration transmitted to the whole body or part of it has been extensively studied in relation to the risks to the health and safety of workers. These studies have highlighted the particular danger of lower-back morbidity and spinal trauma arising after prolonged exposure to vibration. However, short-term exposure to whole-body vibration (WBV) or the use of vibrating dumbbells can have beneficial effects on the musculoskeletal system. As a consequence of this encouraging work, many manufacturers have developed exercise devices characterized by vibrating plates transmitting vibration to the whole body and vibrating dumbbells. Preliminary results seem to recommend WBV exercise as a therapeutic alternative for preventing/reversing sarcopenia and possibly osteoporosis. However, there is a paucity of well designed studies in the elderly. In particular, there is a lack of understanding of the physiological mechanisms involved in the adaptive responses to vibration exposure, and of the most appropriate vibration parameters to be used in order to maximize gains and improve safety. The effectiveness of this novel exercise modality on musculoskeletal structures is examined in this review. The physiological mechanisms involved in the adaptive responses to vibration exercise are discussed and suggestions for future studies are made.

  11. Development of adaptive helicopter seat systems for aircrew vibration mitigation

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Wickramasinghe, Viresh; Zimcik, David G.

    2008-03-01

    Helicopter aircrews are exposed to high levels of whole body vibration during flight. This paper presents the results of an investigation of adaptive seat mount approaches to reduce helicopter aircrew whole body vibration levels. A flight test was conducted on a four-blade helicopter and showed that the currently used passive seat systems were not able to provide satisfactory protection to the helicopter aircrew in both front-back and vertical directions. Long-term exposure to the measured whole body vibration environment may cause occupational health issues such as spine and neck strain injuries for aircrew. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew body. For proof-of-concept demonstration, a miniature modal shaker was properly aligned between the cabin floor and the seat frame to provide adaptive actuation authority. Adaptive control laws were developed to reduce the vibration transmitted to the aircrew body, especially the helmet location in order to minimize neck and spine injuries. Closed-loop control test have been conducted on a full-scale helicopter seat with a mannequin configuration and a large mechanical shaker was used to provide representative helicopter vibration profiles to the seat frame. Significant vibration reductions to the vertical and front-back vibration modes have been achieved simultaneously, which verified the technical readiness of the adaptive mount approach for full-scale flight test on the vehicle.

  12. Force Limited Vibration Testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry; Chang, Kurng Y.

    2005-01-01

    This slide presentation reviews the concept and applications of Force Limited Vibration Testing. The goal of vibration testing of aerospace hardware is to identify problems that would result in flight failures. The commonly used aerospace vibration tests uses artificially high shaker forces and responses at the resonance frequencies of the test item. It has become common to limit the acceleration responses in the test to those predicted for the flight. This requires an analysis of the acceleration response, and requires placing accelerometers on the test item. With the advent of piezoelectric gages it has become possible to improve vibration testing. The basic equations have are reviewed. Force limits are analogous and complementary to the acceleration specifications used in conventional vibration testing. Just as the acceleration specification is the frequency spectrum envelope of the in-flight acceleration at the interface between the test item and flight mounting structure, the force limit is the envelope of the in-flight force at the interface . In force limited vibration tests, both the acceleration and force specifications are needed, and the force specification is generally based on and proportional to the acceleration specification. Therefore, force limiting does not compensate for errors in the development of the acceleration specification, e.g., too much conservatism or the lack thereof. These errors will carry over into the force specification. Since in-flight vibratory force data are scarce, force limits are often derived from coupled system analyses and impedance information obtained from measurements or finite element models (FEM). Fortunately, data on the interface forces between systems and components are now available from system acoustic and vibration tests of development test models and from a few flight experiments. Semi-empirical methods of predicting force limits are currently being developed on the basis of the limited flight and system test

  13. Guidelines for noise and vibration levels for the space station

    NASA Astrophysics Data System (ADS)

    1987-06-01

    Human habitability noise and vibration guidelines for the Space Station are presented. These were developed by a working group of experts established by the Committee on Hearing, Bioacoustics, and Biomechanics (CHABA) of the National Research Council's Commission on Behavioral and Social Science and Education. Noise exposure limits are suggested that will permit adequate speech communication, sleep, and hearing safety. Vibration exposure limits are suggested which will provide adequate comfort and permit adequate task performance. These are provided for guidance only for setting criteria. The exact criteria will depend on Space Station design and duty cycles.

  14. Guidelines for noise and vibration levels for the space station

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Human habitability noise and vibration guidelines for the Space Station are presented. These were developed by a working group of experts established by the Committee on Hearing, Bioacoustics, and Biomechanics (CHABA) of the National Research Council's Commission on Behavioral and Social Science and Education. Noise exposure limits are suggested that will permit adequate speech communication, sleep, and hearing safety. Vibration exposure limits are suggested which will provide adequate comfort and permit adequate task performance. These are provided for guidance only for setting criteria. The exact criteria will depend on Space Station design and duty cycles.

  15. Laboratory and workplace assessments of rivet bucking bar vibration emissions.

    PubMed

    McDowell, Thomas W; Warren, Christopher; Xu, Xueyan S; Welcome, Daniel E; Dong, Ren G

    2015-04-01

    Sheet metal workers operating rivet bucking bars are at risk of developing hand and wrist musculoskeletal disorders associated with exposures to hand-transmitted vibrations and forceful exertions required to operate these hand tools. New bucking bar technologies have been introduced in efforts to reduce workplace vibration exposures to these workers. However, the efficacy of these new bucking bar designs has not been well documented. While there are standardized laboratory-based methodologies for assessing the vibration emissions of many types of powered hand tools, no such standard exists for rivet bucking bars. Therefore, this study included the development of a laboratory-based method for assessing bucking bar vibrations which utilizes a simulated riveting task. With this method, this study evaluated three traditional steel bucking bars, three similarly shaped tungsten alloy bars, and three bars featuring spring-dampeners. For comparison the bucking bar vibrations were also assessed during three typical riveting tasks at a large aircraft maintenance facility. The bucking bars were rank-ordered in terms of unweighted and frequency-weighted acceleration measured at the hand-tool interface. The results suggest that the developed laboratory method is a reasonable technique for ranking bucking bar vibration emissions; the lab-based riveting simulations produced similar rankings to the workplace rankings. However, the laboratory-based acceleration averages were considerably lower than the workplace measurements. These observations suggest that the laboratory test results are acceptable for comparing and screening bucking bars, but the laboratory measurements should not be directly used for assessing the risk of workplace bucking bar vibration exposures. The newer bucking bar technologies exhibited significantly reduced vibrations compared to the traditional steel bars. The results of this study, together with other information such as rivet quality, productivity, tool

  16. Clinical studies of the vibration syndrome using a cold stress test measuring finger temperature.

    PubMed

    Gautherie, M

    1995-01-01

    Since nine years multicentre, transversal and longitudinal clinical studies on hand-arm, vibration-exposed patients are being performed in cooperation with French occupational medicine centers and social security institutions. These studies are based upon current clinical assessment and standardized, temperature-measuring cooling tests. Data acquisition uses a portable, 10-channel, micro-processor-based temperature recorder and miniature thermal sensors. Temperature is monitored at the ten finger tips continuously, before, during and after a cold stress performed in strictly controlled conditions. Data from examinations performed at outlying sites are transferred through the telephonic network to a central processing unit. Data analysis uses a specific, expert-type software procedure based upon previous clinical studies on (i) 238 "normal" subjects, and (ii) 3,046 patients with vascular disturbances of the upper extremities of various etiologies. This procedure includes a staging process which assigns each finger a class representing the degree of severity of the abnormalities of response to cold ("dysthermia") related to vascular disorders. All data processing is fully automatic and results in a printed examination report. To date, over 1,623 vibration-exposed forestry, building and mechanical workers were examined. Sixty-three per cent of patients had received high dose of vibration (daily use of chain saws, air hammers, ballast tampers over many years). Typical white finger attacks or only neurological symptoms were found in 36% and 23% of patients respectively. The rate of sever dysthermia was much higher in patients with white finger attacks (83%) than in patients without (32%). In 90% of the vibration-exposed patients, the severity of dysthermia has differed greatly from one finger to another and between hands, while in non-exposed patients with primary Raynaud syndrome the dysthermia are generally similar for all fingers but the thumbs. Of 208 forestry

  17. The vibrations of texture.

    PubMed

    BensmaIa, Sliman J; Hollins, Mark

    2003-01-01

    The Pacinian channel has been implicated in the perception of fine textures (Hollins et al., Somatosens Mot Res 18: 253-262, 2001a). In the present study, we investigate candidate codes for Pacinian-mediated roughness perception. We use a Hall effect transducer to record the vibrations elicited in the skin when a set of textured surfaces is passively presented to the index finger. The peak frequency of the vibrations is found to decrease systematically as spatial period increases. The power of the vibrations--weighted according to the spectral sensitivity of the Pacinian system--increases with spatial period for all but the coarsest surfaces. By varying the scanning velocity, we manipulate the temporal and intensive characteristics of the texture-induced vibrations and assess the effect of the manipulation on perceived roughness. We find that doubling the scanning velocity does not result in the substantial decrease in roughness predicted by a frequency theory of vibrotactile roughness perception. On the other hand, the effects of speed on roughness match those of speed on power. We propose that the roughness of a fine surface (spatial period<200 microm) is a function of the Pacinian-weighted power of the vibrations it elicits.

  18. The Physics of Vibration

    NASA Astrophysics Data System (ADS)

    Pippard, A. B.

    1989-11-01

    The study of vibration in physical systems is an important part of almost all fields in physics and engineering. This work, originally published in two volumes, examines the classical aspects in Part I and the quantum oscillator in Part II. The classical linear vibrator is treated first and the underlying unity of all linear oscillations in electrical, mechanical and acoustic systems is emphasized. Following this the book turns to the treatment of nonlinear vibrations, a field with which engineers and physicists are generally less familiar. In Part II the emphasis turns to quantum systems, that is those systems which can only be adequately described by quantum mechanics. The treatment concentrates on vibrations in atoms and molecules and their interaction with electromagnetic radiation. The similarities of classical and quantum methods are stressed and the limits of the classical treatment are examined. Throughout the book, each phenomenon discussed is illustrated with many examples and theory and experiment are compared. Although the reader may find that the physics discussed is demanding and the concepts are subtle in places, all mathematics used is familiar to both engineers and experimental scientists. Although not a textbook this is a useful introduction to the more advanced mathematical treatment of vibrations as it bridges the gap between the basic principles and more specialized concepts. It will be of great interest to advanced undergraduates and postgraduates as well as applied mathematicians, physicists and engineers in university and industry.

  19. Multiple vibration displacements at multiple vibration frequencies stress impact on human femur computational analysis.

    PubMed

    Ezenwa, Bertram; Yeoh, Han Teik

    2011-01-01

    Whole-body vibration training using single-frequency methods has been reported to improve bone mineral density. However, the intensities can exceed safe levels and have drawn unfavorable comments from subjects. In a previous article, whole-body vibration training using multiple vibration displacements at multiple vibration frequencies (MVDMVF) was reported. This article presents the computational simulation evaluation of stress dispersion on a femur with and without the MVDMVF input. A model of bone femur was developed from a computed tomography image of the lower limb with Mimics software from Materialise (Plymouth, Michigan). We analyzed the mesh model in COMSOL Multiphysics (COMSOL, Inc; Burlington, Massachusetts) with and without MVDMVF input, with constraints and load applied to the femur model. We compared the results with published joint stresses during walking, jogging, and stair-climbing and descending and with standard vibration exposure limits. Results showed stress levels on the femur are significantly higher with MVDMVF input than without. The stress levels were within the published levels during walking and stair-climbing and descending but below the stress levels during jogging. Our computational results demonstrate that MVDMVF generates stress level equivalent to the level during walking and stair-climbing. This evidence suggests that MVDMVF is safe for prolonged use in subjects with osteoporosis who ambulate independently. PMID:21480091

  20. Vibrational spectroscopy of HNS degradation

    NASA Astrophysics Data System (ADS)

    Alam, M. Kathleen; Martin, Laura; Schmitt, Randal L.; Ten Eyck, Gregory A.; Welle, Eric

    2008-08-01

    Hexanitrostilbene (HNS) is a widely used explosive, due in part to its high thermal stability. Degradation of HNS is known to occur through UV, chemical exposure, and heat exposure, which can lead to reduced performance of the material. Common methods of testing for HNS degradation include wet chemical and surface area testing of the material itself, and performance testing of devices that use HNS. The commonly used chemical tests, such as volatility, conductivity and contaminant trapping provide information on contaminants rather than the chemical stability of the HNS itself. Additionally, these tests are destructive in nature. As an alternative to these methods, we have been exploring the use of vibrational spectroscopy as a means of monitoring HNS degradation non-destructively. In particular, infrared (IR) spectroscopy lends itself well to non-destructive analysis. Molecular variations in the material can be identified and compared to pure samples. The utility of IR spectroscopy was evaluated using pressed pellets of HNS exposed to DETA (diethylaminetriamine). Amines are known to degrade HNS, with the proposed product being a σ-adduct. We have followed these changes as a function of time using various IR sampling techniques including photoacoustic and attenuated total reflectance (ATR).

  1. Fiber optic vibration sensor

    DOEpatents

    Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

    1995-01-10

    A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

  2. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  3. Fiber optic vibration sensor

    DOEpatents

    Dooley, Joseph B.; Muhs, Jeffrey D.; Tobin, Kenneth W.

    1995-01-01

    A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

  4. Vibrational spectroscopy of resveratrol

    NASA Astrophysics Data System (ADS)

    Billes, Ferenc; Mohammed-Ziegler, Ildikó; Mikosch, Hans; Tyihák, Ernő

    2007-11-01

    In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy- trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.

  5. [Clinical and diagnostic value of heart rate variabilities in workers exposed to noise and vibration].

    PubMed

    Serebriakov, P V; Melent'ev, A V; Demina, I D

    2010-01-01

    Noise and vibration cause disorders of vegetative regulation of cardiovascular system. Daily ECG monitoring with heart rate variabilities analysis enables quanitative evaluation of disordered vegetative control over heart rate and diagnosis of cardioneuropathy caused by long occupational exposure to noise and vibration. PMID:20857555

  6. [Effects of licorice (Glycyrrhiza) roots in the rabbit feed on the tachycardiac effect of vibration].

    PubMed

    Oganisian, A O; Oganesian, K R; Minasian, S M

    2010-01-01

    During 30-day feeding with licorice (Glycyrrhiza) roots, further combined 30-day exposure to these roots and vibration prevents the formation of pronounced cardiac rhythm shifts, the emergence of the tachycardic effect of vibration and equilibrates the activity of autonomic mechanisms for cardiac regulation, as suggested by less pronounced changes in the vagosympathetic index.

  7. Vibration Propagation in Spider Webs

    NASA Astrophysics Data System (ADS)

    Hatton, Ross; Otto, Andrew; Elias, Damian

    Due to their poor eyesight, spiders rely on web vibrations for situational awareness. Web-borne vibrations are used to determine the location of prey, predators, and potential mates. The influence of web geometry and composition on web vibrations is important for understanding spider's behavior and ecology. Past studies on web vibrations have experimentally measured the frequency response of web geometries by removing threads from existing webs. The full influence of web structure and tension distribution on vibration transmission; however, has not been addressed in prior work. We have constructed physical artificial webs and computer models to better understand the effect of web structure on vibration transmission. These models provide insight into the propagation of vibrations through the webs, the frequency response of the bare web, and the influence of the spider's mass and stiffness on the vibration transmission patterns. Funded by NSF-1504428.

  8. Blade Vibration Measurement System

    NASA Technical Reports Server (NTRS)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  9. Compact Vibration Damper

    NASA Technical Reports Server (NTRS)

    Ivanco, Thomas G. (Inventor)

    2014-01-01

    A vibration damper includes a rigid base with a mass coupled thereto for linear movement thereon. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A converter coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement.

  10. Nonlinear vibrational microscopy

    DOEpatents

    Holtom, Gary R.; Xie, Xiaoliang Sunney; Zumbusch, Andreas

    2000-01-01

    The present invention is a method and apparatus for microscopic vibrational imaging using coherent Anti-Stokes Raman Scattering or Sum Frequency Generation. Microscopic imaging with a vibrational spectroscopic contrast is achieved by generating signals in a nonlinear optical process and spatially resolved detection of the signals. The spatial resolution is attained by minimizing the spot size of the optical interrogation beams on the sample. Minimizing the spot size relies upon a. directing at least two substantially co-axial laser beams (interrogation beams) through a microscope objective providing a focal spot on the sample; b. collecting a signal beam together with a residual beam from the at least two co-axial laser beams after passing through the sample; c. removing the residual beam; and d. detecting the signal beam thereby creating said pixel. The method has significantly higher spatial resolution then IR microscopy and higher sensitivity than spontaneous Raman microscopy with much lower average excitation powers. CARS and SFG microscopy does not rely on the presence of fluorophores, but retains the resolution and three-dimensional sectioning capability of confocal and two-photon fluorescence microscopy. Complementary to these techniques, CARS and SFG microscopy provides a contrast mechanism based on vibrational spectroscopy. This vibrational contrast mechanism, combined with an unprecedented high sensitivity at a tolerable laser power level, provides a new approach for microscopic investigations of chemical and biological samples.

  11. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

  12. High-Temperature Vibration Damper

    NASA Technical Reports Server (NTRS)

    Clarke, Alan; Litwin, Joel; Krauss, Harold

    1987-01-01

    Device for damping vibrations functions at temperatures up to 400 degrees F. Dampens vibrational torque loads as high as 1,000 lb-in. but compact enough to be part of helicopter rotor hub. Rotary damper absorbs energy from vibrating rod, dissipating it in turbulent motion of viscous hydraulic fluid forced by moving vanes through small orifices.

  13. Vibration characteristics of ultrasonic complex vibration for hole machining

    NASA Astrophysics Data System (ADS)

    Asami, Takuya; Miura, Hikaru

    2012-05-01

    Complex vibration sources that use diagonal slits as a longitudinal-torsional vibration converter have been applied to ultrasonic motors, ultrasonic rock drilling, and ultrasonic welding. However, there are few examples of the application of these sources to ultrasonic machining in combination with an abrasive. Accordingly, a new method has been developed for machining of holes in brittle materials by using the ultrasonic longitudinal and torsional vibration of a hollow-type stepped horn with a diagonal slit vibration converter. In this paper, we compared vibration of a uniform rod and a hollow-type stepped horn, both with diagonal slits, when the conditions of the diagonal slits are constant.

  14. Effect of Vibrations on Transportation System

    NASA Astrophysics Data System (ADS)

    Birlik, Gülin; Sezgin, Önder Cem

    In overly populated cities people living in suburban areas have to endure long journeys in order to reach their job sites. Whether they go by train, bus or by car they are inevitably exposed to vibrations, of considerable magnitude, in vertical (z) and lateral (x, y) directions. The immediate effect of vibration exposure is the fatigue of ones' muscles. This is verified by the blood and saliva analysis of the volunteers travelling in a train. Their lactic acid levels were increased by 34% at the end of a 5 hr journey. The most affected people by vibration were, without doubt, the train operators and bus drivers. 42% of the suburban train operators had pain complaints at their waists. az(floor) in the machinist cabin of a suburban train was measured to be, on the average, 0.23 m/s2. Max peak was 1.34 m/s2. The bus and car drivers were exposed to lower vibrations but they were exposed to multiple shocks originating from the non-standardized humps placed on the roads. Peak az(seat) = 0.054 m/s2 (f = 5.25 Hz) (vcar = 30 km/hr) on an asphalt road increased considerably while crossing over a hump. This value was 1.27 m/s2 (f = 4.5 Hz) in case of bus drivers (vbus = 20 km/hr). Studies have been done to provide practical measures for the reduction of the vibrations transmitted to the drivers. The waist belts filled with fluids of different viscosities prepared for this purpose seemed to be promising. The cushions filled with glycerin and gel were observed to be the best alternatives.

  15. Human annoyance, acceptability and concern as responses to vibration from the construction of Light Rapid Transit lines in residential environments.

    PubMed

    Wong-McSweeney, D; Woodcock, J S; Peris, E; Waddington, D C; Moorhouse, A T; Redel-Macías, M D

    2016-10-15

    The aim of this paper is to investigate the use of different self-reported measures for assessing the human response to environmental vibration from the construction of an urban LRT (Light Rapid Transit) system. The human response to environmental stressors such as vibration and noise is often expressed in terms of exposure-response relationships that describe annoyance as a function of the magnitude of the vibration. These relationships are often the basis of noise and vibration policy and the setting of limit values. This paper examines measures other than annoyance by expressing exposure-response relationships for vibration in terms of self-reported concern about property damage and acceptability. The exposure-response relationships for concern about property damage and for acceptability are then compared with those for annoyance. It is shown that concern about property damage occurs at vibration levels well below those where there is any risk of damage. Earlier research indicated that concern for damage is an important moderator of the annoyance induced. Acceptability, on the other hand, might be influenced by both annoyance and concern, as well as by other considerations. It is concluded that exposure-response relationships expressing acceptability as a function of vibration exposure could usefully complement existing relationships for annoyance in future policy decisions regarding environmental vibration. The results presented in this paper are derived from data collected through a socio-vibration survey (N=321) conducted for the construction of an urban LRT in the United Kingdom. PMID:26875606

  16. Human annoyance, acceptability and concern as responses to vibration from the construction of Light Rapid Transit lines in residential environments.

    PubMed

    Wong-McSweeney, D; Woodcock, J S; Peris, E; Waddington, D C; Moorhouse, A T; Redel-Macías, M D

    2016-10-15

    The aim of this paper is to investigate the use of different self-reported measures for assessing the human response to environmental vibration from the construction of an urban LRT (Light Rapid Transit) system. The human response to environmental stressors such as vibration and noise is often expressed in terms of exposure-response relationships that describe annoyance as a function of the magnitude of the vibration. These relationships are often the basis of noise and vibration policy and the setting of limit values. This paper examines measures other than annoyance by expressing exposure-response relationships for vibration in terms of self-reported concern about property damage and acceptability. The exposure-response relationships for concern about property damage and for acceptability are then compared with those for annoyance. It is shown that concern about property damage occurs at vibration levels well below those where there is any risk of damage. Earlier research indicated that concern for damage is an important moderator of the annoyance induced. Acceptability, on the other hand, might be influenced by both annoyance and concern, as well as by other considerations. It is concluded that exposure-response relationships expressing acceptability as a function of vibration exposure could usefully complement existing relationships for annoyance in future policy decisions regarding environmental vibration. The results presented in this paper are derived from data collected through a socio-vibration survey (N=321) conducted for the construction of an urban LRT in the United Kingdom.

  17. Active vibration control of structures undergoing bending vibrations

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

    1995-01-01

    An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

  18. The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions.

    PubMed

    McDowell, Thomas W; Welcome, Daniel E; Warren, Christopher; Xu, Xueyan S; Dong, Ren G

    2016-04-01

    Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank

  19. The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions

    PubMed Central

    McDowell, Thomas W.; Welcome, Daniel E.; Warren, Christopher; Xu, Xueyan S.; Dong, Ren G.

    2016-01-01

    Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank

  20. Free vibrations of delaminated beams

    NASA Technical Reports Server (NTRS)

    Shen, M.-H. H.; Grady, J. E.

    1992-01-01

    Free vibration of laminated composite beams is studied. The effect of interply delaminations on natural frequencies and mode shapes is evaluated both analytically and experimentally. A generalized vibrational principle is used to formulate the equation of motion and associated boundary conditions for the free vibration of a composite beam with a delamination of arbitrary size and location. The effect of coupling between longitudinal vibration and bending vibration is considered. This coupling effect is shown to significantly affect the calculated natural frequencies and mode shapes of the delaminated beam.

  1. Vibration sensing method and apparatus

    DOEpatents

    Barna, B.A.

    1987-07-07

    A method and apparatus for nondestructive evaluation of a structure is disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration. 4 figs.

  2. Vibration sensing method and apparatus

    DOEpatents

    Barna, B.A.

    1989-04-25

    A method and apparatus for nondestructive evaluation of a structure are disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration. 4 figs.

  3. Vibration sensing method and apparatus

    DOEpatents

    Barna, Basil A.

    1989-04-25

    A method and apparatus for nondestructive evaluation of a structure is disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration.

  4. Animal Communications Through Seismic Vibrations

    SciTech Connect

    Hill, Peggy

    2001-05-02

    Substrate vibration has been important to animals as a channel of communication for millions of years, but our literature on vibration in this context of biologically relevant information is only decades old. The jaw mechanism of the earliest land vertebrates allowed them to perceive substrate vibrations as their heads lay on the ground long before airborne sounds could be heard. Although the exact mechanism of vibration production and the precise nature of the wave produced are not always understood, recent development of affordable instrumentation to detect and measure vibrations has allowed researchers to answer increasingly sophisticated questions about how animals send and receive vibration signals. We now know that vibration provides information used in predator defense, prey detection, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions in a variety of insect orders, spiders, crabs, scorpions, chameleons, frogs, golden moles, mole rats, kangaroos rats, wallabies, elephants and bison.

  5. Molecular vibrational energy flow

    NASA Astrophysics Data System (ADS)

    Gruebele, M.; Bigwood, R.

    This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.

  6. Thermoelastic vibration test techniques

    NASA Technical Reports Server (NTRS)

    Kehoe, Michael W.; Snyder, H. Todd

    1991-01-01

    The structural integrity of proposed high speed aircraft can be seriously affected by the extremely high surface temperatures and large temperature gradients throughout the vehicle's structure. Variations in the structure's elastic characteristics as a result of thermal effects can be observed by changes in vibration frequency, damping, and mode shape. Analysis codes that predict these changes must be correlated and verified with experimental data. The experimental modal test techniques and procedures used to conduct uniform, nonuniform, and transient thermoelastic vibration tests are presented. Experimental setup and elevated temperature instrumentation considerations are also discussed. Modal data for a 12 by 50 inch aluminum plate heated to a temperature of 475 F are presented. These data show the effect of heat on the plate's modal characteristics. The results indicated that frequency decreased, damping increased, and mode shape remained unchanged as the temperature of the plate was increased.

  7. Possible Mechanisms of Low Back Pain due to Whole-Body Vibration

    NASA Astrophysics Data System (ADS)

    Pope, M. H.; Wilder, D. G.; Magnusson, M.

    1998-08-01

    The investigators describe their multifaceted approach to the study of the relationship between whole-body vibration and low back pain.In vitroexperiments, using percutaneous pin-mounted accelerometers have shown that the natural frequency is at 4·5 Hz. The frequency response was affected by posture, seating, and seat-back inclination. The response appears to be largely determined by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration should be reduced for those recovering from these problems. Vibration attenuating seats, and correct ergonomic layout of the cabs may reduce the risks of recurrence.

  8. Evaluation of human response to structural vibrations induced by sonic booms

    NASA Technical Reports Server (NTRS)

    Sutherland, Louis C.; Czech, J.

    1992-01-01

    The topic is addressed of building vibration response to sonic boom and the evaluation of the associated human response to this vibration. An attempt is made to reexamine some of the issues addressed previously and to offer fresh insight that may assist in reassessing the potential impact of sonic boom over populated areas. Human response to vibration is reviewed first and a new human vibration response criterion curve is developed as a function of frequency. The difference between response to steady state versus impulsive vibration is addressed and a 'vibration exposure' or 'vibration energy' descriptor is suggested as one possible way to evaluate duration effects on response to transient vibration from sonic booms. New data on the acoustic signature of rattling objects are presented along with a review of existing data on the occurrence of rattle. Structural response to sonic boom is reviewed and a new descriptor, 'Acceleration Exposure Level' is suggested which can be easily determined from the Fourier Spectrum of a sonic boom. A preliminary assessment of potential impact from sonic booms is provided in terms of human response to vibration and detection of rattle based on a synthesis of the preceding material.

  9. Effect of situational, attitudinal and demographic factors on railway vibration annoyance in residential areas.

    PubMed

    Peris, Eulalia; Woodcock, James; Sica, Gennaro; Sharp, Calum; Moorhouse, Andrew T; Waddington, David C

    2014-01-01

    Railway induced vibration is an important source of annoyance among residents living in the vicinity of railways. Annoyance increases with vibration magnitude. However, these correlations between the degree of annoyance and vibration exposure are weak. This suggests that railway vibration induced annoyance is governed by more than just vibration level and therefore other factors may provide information to understand the wide variation in annoyance reactions. Factors coming into play when considering an exposure-response relationship between level of railway vibration and annoyance are presented. The factors investigated were: attitudinal, situational and demographic factors. This was achieved using data from field studies comprised of face-to-face interviews and internal vibration measurements (N = 755). It was found that annoyance scores were strongly influenced by two attitudinal factors: Concern of property damage and expectations about future levels of vibration. Type of residential area and age of the respondent were found to have an important effect on annoyance whereas visibility of the railway and time spent at home showed a significant but small influence. These results indicate that future railway vibration policies and regulations focusing on community impact need to consider additional factors for an optimal assessment of railway effects on residential environments.

  10. Vibrational stability of graphene

    NASA Astrophysics Data System (ADS)

    Hu, Yangfan; Wang, Biao

    2013-05-01

    The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP) models. Compared with three-dimensional (3-D) materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202). This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC), defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D) materials.

  11. Vibrational Dynamics of Tricyanomethanide

    NASA Astrophysics Data System (ADS)

    Weidinger, Daniel; Houchins, Cassidy; Owrutsky, Jeffrey C.

    2011-06-01

    Time-resolved and steady-state IR spectroscopy have been used to characterize vibrational spectra and energy relaxation dynamics of the CN stretching band of the tricyanomethanide (TCM, C(CN)3-) anion near 2170 Cm-1 in solutions of water, heavy water, methanol, formamide, dimethyl sulfoxide (DMSO) and the ionic liquid 1-butyl methyl imidazolium tetrafluoroborate ([BMIM][BF4]). The band intensity is strong (˜1500 M-1Cm-1) and the vibrational energy relaxation times are relatively long (˜5 ps in water, 12 ps in heavy water, and ˜30 ps in DMSO and [BMIM][BF4]). They are longer than those previously reported for dicyanamide in the same solvents. Although the static TCM frequency generally shifts to higher frequency with more strongly interacting solvents, the shift does not follow the same trend as the vibrational dynamics. The results for the experimental frequencies and intensities agree well with results from ab initio calculations. Proton and electron affinities for TCM are also calculated because they are relevant to potential applications of this anion in low viscosity ionic liquids.

  12. Vibrational Echo Correlation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Asbury, John B.; Steinel, Tobias; Fayer, M. D.

    Multidimensional vibrational echo correlation spectroscopy with full phase resolution is used to measure hydrogen bond dynamics in water and methanol. The OD hydroxyl stretches of methanol-OD oligomers in CCl4 and HOD inH2O are studied using the shortest mid-IR pulses (< 45 fs, < 4 cycles of light) produced to date. The pulses have sufficient spectral bandwidth to span the very broad (> 400 cm-1) spectrum of the 0-1 and 1-2 vibrational transitions. Hydrogen bond population dynamics are extricated with exceptional detail in MeOD oligomers because the different hydrogen-bonded species are spectrally distinct. The experimental results along with detailed calculations indicate the strongest hydrogen bonds are selectively broken through a non-equilibrium relaxation pathway following vibrational relaxation of the hydroxyl stretch. Following hydrogen bond breaking, the broken MeOD oligomers retain a detailed structural memory of the prior intact hydrogen bond network. The correlation spectra are also a sensitive probe of the structural fluctuations in water and provide a stringent test of water models that are widely used in simulations of aqueous systems. The analysis of the 2D band shapes demonstrates that different hydrogen-bonded species are subject to distinct (wavelength-dependent) ultrafast (˜ 100 fs) local fluctuations and essentially identical slower (0.4 ps and ˜ 2 ps) structural rearrangements. Observation of wavelength-dependent dynamics demonstrates that standard theoretical approaches assuming Gaussian fluctuations cannot adequately describe water dynamics.

  13. Estimate exchanger vibration

    SciTech Connect

    Nieh, C.D.; Zengyan, H.

    1986-04-01

    Based on the classical beam theory, a simple method for calculating the natural frequency of unequally spanned tubes is presented. The method is suitable for various boundary conditions. Accuracy of the calculations is sufficient for practical applications. This method will help designers and operators estimate the vibration of tubular exchangers. In general, there are three reasons why a tube vibrates in cross flow: vortex shedding, fluid elasticity and turbulent buffeting. No matter which is the cause, the basic reason is that the frequency of exciting force is approximately the same as or equal to the natural frequency of the tube. To prevent the heat exchanger from vibrating, it is necessary to select correctly the shell-side fluid velocity so that the frequency of exciting force is different from the natural frequency of the tube, or to vary the natural frequency of the heat exchanger tube. So precisely determining the natural frequency of the heat exchanger, especially its foundational frequency under various supporting conditions, is of significance.

  14. Vibration from freight trains fragments sleep: A polysomnographic study

    PubMed Central

    Smith, Michael G.; Croy, Ilona; Hammar, Oscar; Persson Waye, Kerstin

    2016-01-01

    As the number of freight trains on railway networks increases, so does the potential for vibration exposure in dwellings nearby to freight railway lines. Nocturnal trains in particular are of particular importance since night-time exposure may interfere with sleep. The present work investigates the impact of vibration and noise from night-time freight trains on human sleep. In an experimental polysomnographic laboratory study, 24 young healthy volunteers with normal hearing were exposed to simulated freight pass-bys with vibration amplitudes of 0.7 and 1.4 mm/s either 20 or 36 times during the night. Stronger vibrations were associated with higher probabilities of event-related arousals and awakenings (p < 0.001), and sleep stage changes (p < 0.05). Sleep macrostructure was most affected in high vibration nights with 36 events, with increased wakefulness (p < 0.05), reduced continual slow wave sleep (p < 0.05), earlier awakenings (p < 0.05) and an overall increase in sleep stage changes (p < 0.05). Subjects reported sleep disturbance due to vibration (F(4,92) = 25.9, p < 0.001) and noise (F(4,92) = 25.9, p < 0.001), with the number of trains having an effect only for the 0.7 mm/s condition (p < 0.05). The findings show that combined vibration and noise from railway freight affects the natural rhythm of sleep, but extrapolation of significance for health outcomes should be approached with caution. PMID:27090401

  15. Vibration Considerations for Cryogenic Tanks Using Glass Bubbles Insulation

    NASA Technical Reports Server (NTRS)

    Werlink, Rudolph J.; Fesmire, James E.; Sass, Jared P.

    2011-01-01

    The use of glass bubbles as an efficient and practical thermal insulation system has been previously demonstrated in cryogenic storage tanks. One such example is a spherical, vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate has been reduced by approximately 50 percent. Further applications may include non-stationary tanks such as mobile tankers and tanks with extreme duty cycles or exposed to significant vibration environments. Space rocket launch events and mobile tanker life cycles represent two harsh cases of mechanical vibration exposure. A number of bulk fill insulation materials including glass bubbles, perlite powders, and aerogel granules were tested for vibration effects and mechanical behavior using a custom design holding fixture subjected to random vibration on an Electrodynamic Shaker. The settling effects for mixtures of insulation materials were also investigated. The vibration test results and granular particle analysis are presented with considerations and implications for future cryogenic tank applications. A thermal performance update on field demonstration testing of a 218,000 L liquid hydrogen storage tank, retrofitted with glass bubbles, is presented. KEYWORDS: Glass bubble, perlite, aerogel, insulation, liquid hydrogen, storage tank, mobile tanker, vibration.

  16. Exposure of emergency medicine personnel to ionizing radiation during cervical spine radiography

    SciTech Connect

    Singer, C.M.; Baraff, L.J.; Benedict, S.H.; Weiss, E.L.; Singer, B.D.

    1989-08-01

    We studied the potential hazard of ionizing radiation exposure to health care workers who routinely stabilize the necks of trauma patients during cervical spine radiography. A clinical trauma model was developed using an Alderson RANDO Phantom artificial torso to simulate an actual patient. A radiation monitor was placed where a health care worker's fingers, hands, arms, and thyroid gland would be, and standard cervical spine radiographs were taken. The exposures to the finger positions then were repeated with the monitor inside a 0.5 mm lead-equivalent glove. The mean exposure to the finger for a single cross-table lateral radiograph was 174.5 mrem. The use of leaded gloves reduced this exposure to 0.3 mrem (a 99.9% reduction). For a single series of lateral, anteroposterior, odontoid, and swimmer's views, the total mean measured unprotected exposure to the finger of the hand positioned nearest the radiographic tube was 681 mrem and the exposure to the finger of the opposite hand was 230 mrem. If these simulated exposures are indicative of actual patient situations, a health care worker who holds the head of a trauma patient four times each week with unshielded hands would receive more than twice the maximum allowable annual occupational radiation exposure to the extremities recommended by the National Council of Radiation Protection and Measurements. We conclude that health care workers who routinely stabilize the necks of trauma patients during cervical spine radiography may incur a radiation exposure risk and that 0.5-mm lead-equivalent gloves provide an effective barrier to ionizing radiation.

  17. Vibrational averages along thermal lines

    NASA Astrophysics Data System (ADS)

    Monserrat, Bartomeu

    2016-01-01

    A method is proposed for the calculation of vibrational quantum and thermal expectation values of physical properties from first principles. Thermal lines are introduced: these are lines in configuration space parametrized by temperature, such that the value of any physical property along them is approximately equal to the vibrational average of that property. The number of sampling points needed to explore the vibrational phase space is reduced by up to an order of magnitude when the full vibrational density is replaced by thermal lines. Calculations of the vibrational averages of several properties and systems are reported, namely, the internal energy and the electronic band gap of diamond and silicon, and the chemical shielding tensor of L-alanine. Thermal lines pave the way for complex calculations of vibrational averages, including large systems and methods beyond semilocal density functional theory.

  18. Guidelines for Whole-Body Vibration Health Surveillance

    NASA Astrophysics Data System (ADS)

    POPE, M.; MAGNUSSON, M.; LUNDSTRÖM, R.; HULSHOF, C.; VERBEEK, J.; BOVENZI, M.

    2002-05-01

    There is strong epidemiological evidence that occupational exposure to WBV is associated with an increased risk of low back pain (LBP), sciatic pain, and degenerative changes in the spinal system, including lumbar intervertebral disc disorders. A prototype health surveillance scheme for WBV is presented in this paper. Surveillance is the collection, analysis, and dissemination of data for the purpose of prevention. The aims are to assess health status and diagnose vibration-induced disorders at an early stage, to inform the workers on the potential risk associated with vibration exposure, to give preventive advice to employers and employees and to control whether preventive measures which have been taken, were successful. It is suggested that a pre-placement health examination should be offered to each worker who will be exposed to WBV so as to make the worker aware of the hazards, to obtain baseline health data, and to identify medical conditions that may increase the risk due to WBV. The case history should focus on personal history, work history, and leisure activities involving driving of vehicles. The personal medical history should detail back pain complaints, disorders in the spine, any injuries or surgery to the musculoskeletal system. A physical examination on the lower back should be performed on workers who have experienced LBP symptoms over the past 12 months. The preplacement examination should be followed by periodic health reassessment with a regular interval according to the legislation of the country. It is suggested that periodic medical examination should be made available at least every 2 years to all workers who are exposed to WBV. Any change in vibration exposure at the workplace should be reported by the employer. If an increase in vibration exposure or a change in health status have occurred, the medical re-examination should be offered at shorter intervals at the discretion of the attending physician. There should be a periodic medical

  19. Flow-induced vibrations-1987

    SciTech Connect

    Au-Yang, M.K.; Chen, S.S.

    1987-01-01

    This book contains 20 selections. Some of the titles are: Acoustic resonance in heat exchanger tube bundles--Part 1. Physical nature of the phenomenon; Theoretical and experimental studies on heat exchanger U-bend tube bundle vibration characteristics; Experimental model analysis of metallic pipeline conveying fluid; Leakage flow-induced vibration of an eccentric tube-in-tube slip joint; and A study on the vibrations of pipelines caused by internal pulsating flows.

  20. Vibration damping method and apparatus

    DOEpatents

    Redmond, J.M.; Barney, P.S.; Parker, G.G.; Smith, D.A.

    1999-06-22

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof. 38 figs.

  1. Vibration damping method and apparatus

    DOEpatents

    Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.

    1999-01-01

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.

  2. Characteristics of Vibration that Alter Cardiovascular Parameters in Mice.

    PubMed

    Li, Yao; Rabey, Karyne N; Schmitt, Daniel; Norton, John N; Reynolds, Randall P

    2015-07-01

    We hypothesized that short-term exposure of mice to vibration within a frequency range thought to be near the resonant frequency range of mouse tissue and at an acceleration of 0 to 1 m/s(2) would alter heart rate (HR) and mean arterial pressure (MAP). We used radiotelemetry to evaluate the cardiovascular response to vibration in C57BL/6 and CD1 male mice exposed to vertical vibration of various frequencies and accelerations. MAP was consistently increased above baseline values at an acceleration near 1 m/s(2) and a frequency of 90 Hz in both strains, and HR was increased also in C57BL/6 mice. In addition, MAP increased at 80 Hz in individual mice of both strains. When both strains were analyzed together, mean MAP and HR were increased at 90 Hz at 1 m/s(2), and HR was increased at 80 Hz at 1 m/s(2). No consistent change in MAP or HR occurred when mice were exposed to frequencies below 80 Hz or above 90 Hz. The increase in MAP and HR occurred only when the mice had conscious awareness of the vibration, given that these changes did not occur when anesthetized mice were exposed to vibration. Tested vibration acceleration levels lower than 0.75 m/s(2) did not increase MAP or HR at 80 or 90 Hz, suggesting that a relatively high level of vibration is necessary to increase these parameters. These data are important to establish the harmful frequencies and accelerations of environmental vibration that should be minimized or avoided in mouse facilities.

  3. Measuring Vibrations With Nonvibration Sensors

    NASA Technical Reports Server (NTRS)

    Hill, Arthur J.

    1988-01-01

    Information about vibrations of structure and/or of nonvibration sensor attached to structure extracted from output of sensor. Sensor operated in usual way except, output fed to power-spectral-density analyzer. Vibrational components easily distinguishable in analyzer output because they have frequencies much higher than those of more-slowly-varying temperature, pressure, or other normally desired components. Spectral-analysis technique applied successfully to high-frequency resistance changes in output of platinum-wire resistance thermometer: vibrational peaks in resistance frequency spectrum confirmed by spectrum from accelerometer. Technique also showed predicted 17-kHz vibrational resonance in strain-guage-supporting beam in pressure sensor.

  4. Computer analysis of railcar vibrations

    NASA Technical Reports Server (NTRS)

    Vlaminck, R. R.

    1975-01-01

    Computer models and techniques for calculating railcar vibrations are discussed along with criteria for vehicle ride optimization. The effect on vibration of car body structural dynamics, suspension system parameters, vehicle geometry, and wheel and rail excitation are presented. Ride quality vibration data collected on the state-of-the-art car and standard light rail vehicle is compared to computer predictions. The results show that computer analysis of the vehicle can be performed for relatively low cost in short periods of time. The analysis permits optimization of the design as it progresses and minimizes the possibility of excessive vibration on production vehicles.

  5. Electronic damping of mechanical vibrations

    NASA Technical Reports Server (NTRS)

    Vasilyev, P.; Navitskas, A.

    1973-01-01

    The conditions required for measuring and recording the patterns of vibration of a process are discussed. It is stated that the frequency of the process being investigated must be an order of magnitude lower than the natural frequency of the sensitive receiving element for sufficient accuracy. The elastic element must damp so the frequency range of the vibrational patterns being investigated can be expanded. This is especially true of the tensile stresses of a moving signal carrier. A method is proposed for damping mechanical vibrations of elastic sensitive elements with semiconductor strain gages, based on electronic compensation of the natural vibrations. A schematic diagram is provided to show the conditions.

  6. Resonance vibrations of aircraft propellers

    NASA Technical Reports Server (NTRS)

    Liebers, Fritz

    1932-01-01

    On the basis of the consideration of various possible kinds of propeller vibrations, the resonance vibrations caused by unequal impacts of the propeller blades appear to be the most important. Their theoretical investigation is made by separate analysis of torsional and bending vibrations. This method is justified by the very great difference in the two natural frequencies of aircraft propeller blades. The calculated data are illustrated by practical examples. Thereby the observed vibration phenomenon in the given examples is explained by a bending resonance, for which the bending frequency of the propeller is equal to twice the revolution speed.

  7. Turbine blade vibration dampening

    DOEpatents

    Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

  8. Turbine blade vibration dampening

    DOEpatents

    Cornelius, Charles C.; Pytanowski, Gregory P.; Vendituoli, Jonathan S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

  9. Chaotic vortex induced vibrations

    SciTech Connect

    Zhao, J.; Sheridan, J.; Leontini, J. S.; Lo Jacono, D.

    2014-12-15

    This study investigates the nature of the dynamic response of an elastically mounted cylinder immersed in a free stream. A novel method is utilized, where the motion of the body during a free vibration experiment is accurately recorded, and then a second experiment is conducted where the cylinder is externally forced to follow this recorded trajectory. Generally, the flow response during both experiments is identical. However, particular regimes exist where the flow response is significantly different. This is taken as evidence of chaos in these regimes.

  10. [Management of the worker affected by shoulder pathology].

    PubMed

    Rotini, Roberto; Bonfiglioli, Roberta

    2014-01-01

    Shoulder disorders due to overexertion include joint and soft tissues chronic conditions and are an important cause of disability. Shoulder pain is one of the most common musculoskeletal disorders and has been associated to manual handling of heavy loads, high repetition jobs, exposure to hand-arm vibration and to overhead activities. Diagnosis of shoulder disorders is primarily based on clinical examination; selected cases should be referred to an orthopedic specialist and to imaging. Return to normal activities should be encouraged.

  11. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  12. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  13. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  14. Vibration considerations for cryogenic tanks using glass bubbles insulation

    NASA Astrophysics Data System (ADS)

    Werlink, Rudy John; Fesmire, James; Sass, Jared P.

    2012-06-01

    The use of glass bubbles as an efficient and practical thermal insulation system hasbeen previously demonstrated in cryogenic storage tanks. One such example is a spherical,vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate hasbeen reduced by approximately 50 percent. Further applications may include non-stationarytanks such as mobile tankers and tanks with extreme duty cycles or exposed to significantvibration environments. Space rocket launch events and mobile tanker life cycles representtwo harsh cases of mechanical vibration exposure. A number of bulk fill insulationmaterials including glass bubbles, perlite powders, and aerogel granules were tested forvibration effects and mechanical behavior using a custom design holding fixture subjectedto random vibration on an Electrodynamic Shaker. The settling effects for mixtures ofinsulation materials were also investigated. The vibration test results and granular particleanalysis are presented with considerations and implications for future cryogenic tankapplications.

  15. Longitudinally-vibrating surgical microelectrode

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Crawford, D.; Kawabus, E. W.

    1977-01-01

    Microelectrode attached to cone of loudspeaker imparting longitudinal vibrations, penetrates relatively tough tissue of arterial walls easier and with more precise depth control because dimpling is eliminated. Vibrating microelectrode has been successfully used to make accurate oxygen-content measurements in arterial walls.

  16. Vibration Response of Airplane Structures

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Gelalles, A G

    1935-01-01

    This report presents test results of experiments on the vibration-response characteristics of airplane structures on the ground and in flight. It also gives details regarding the construction and operation of vibration instruments developed by the National Advisory Committee for Aeronautics.

  17. The origins of vibration theory

    NASA Astrophysics Data System (ADS)

    Dimarogonas, A. D.

    1990-07-01

    The Ionian School of natural philosophy introduced the scientific method of dealing with natural phenomena and the rigorous proofs for abstract propositions. Vibration theory was initiated by the Pythagoreans in the fifth century BC, in association with the theory of music and the theory of acoustics. They observed the natural frequency of vibrating systems and proved that it is a system property and that it does not depend on the excitation. Pythagoreans determined the fundamental natural frequencies of several simple systems, such as vibrating strings, pipes, vessels and circular plates. Aristoteles and the Peripatetic School founded mechanics and developed a fundamental understanding of statics and dynamics. In Alexandrian times there were substantial engineering developments in the field of vibration. The pendulum as a vibration, and probably time, measuring device was known in antiquity, and was further developed by the end of the first millennium AD.

  18. Low Cost Digital Vibration Meter

    PubMed Central

    Payne, W. Vance; Geist, Jon

    2007-01-01

    This report describes the development of a low cost, digital Micro Electro Mechanical System (MEMS) vibration meter that reports an approximation to the RMS acceleration of the vibration to which the vibration meter is subjected. The major mechanical element of this vibration meter is a cantilever beam, which is on the order of 500 µm in length, with a piezoresistor deposited at its base. Vibration of the device in the plane perpendicular to the cantilever beam causes it to bend, which produces a measurable change in the resistance of a piezoresistor. These changes in resistance along with a unique signal-processing scheme are used to determine an approximation to the RMS acceleration sensed by the device. PMID:27110459

  19. Coherent vibrational climbing in carboxyhemoglobin.

    PubMed

    Ventalon, Cathie; Fraser, James M; Vos, Marten H; Alexandrou, Antigoni; Martin, Jean-Louis; Joffre, Manuel

    2004-09-01

    We demonstrate vibrational climbing in the CO stretch of carboxyhemoglobin pumped by midinfrared chirped ultrashort pulses. By use of spectrally resolved pump-probe measurements, we directly observed the induced absorption lines caused by excited vibrational populations up to v = 6. In some cases, we also observed stimulated emission, providing direct evidence of vibrational population inversion. This study provides important spectroscopic parameters on the CO stretch in the strong-field regime, such as transition frequencies and dephasing times up to the v = 6 to v = 7 vibrational transition. We measured equally spaced vibrational transitions, in agreement with the energy levels of a Morse potential up to v = 6. It is interesting that the integral of the differential absorption spectra was observed to deviate far from zero, in contrast to what one would expect from a simple one-dimensional Morse model assuming a linear dependence of dipole moment with bond length.

  20. Force Limited Vibration Testing Monograph

    NASA Technical Reports Server (NTRS)

    Scharton, Terry D.

    1997-01-01

    The practice of limiting the shaker force in vibration tests was investigated at the NASA Jet Propulsion Laboratory (JPL) in 1990 after the mechanical failure of an aerospace component during a vibration test. Now force limiting is used in almost every major vibration test at JPL and in many vibration tests at NASA Goddard Space Flight Center (GSFC) and at many aerospace contractors. The basic ideas behind force limiting have been in the literature for several decades, but the piezo-electric force transducers necessary to conveniently implement force limiting have been available only in the last decade. In 1993, funding was obtained from the NASA headquarters Office of Chief Engineer to develop and document the technology needed to establish force limited vibration testing as a standard approach available to all NASA centers and aerospace contractors. This monograph is the final report on that effort and discusses the history, theory, and applications of the method in some detail.

  1. Vibration analysis using digital correlation

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.; Lehner, David L.; Dudderar, T. Dixon; Matthys, Donald R.

    1988-01-01

    This paper demonstrates the use of a computer-based optical method for locating the positions of nodes and antinodes in vibrating members. Structured light patterns are projected at an angle onto the vibrating surface using a 35 mm slide projector. The vibrating surface and the projected images are captured in a time averaged photograph which is subsequently digitized. The inherent fringe patterns are filtered to determine amplitudes of vibration, and computer programs are used to compare the time averaged images to images recorded prior to excitation to locate nodes and antinodes. Some of the influences of pattern regularity on digital correlation are demonstrated, and a speckle-based method for determining the mode shapes and the amplitudes of vibration with variable sensitivity is suggested.

  2. Violin bow vibrations.

    PubMed

    Gough, Colin E

    2012-05-01

    The modal frequencies and bending mode shapes of a freely supported tapered violin bow are investigated by finite element analysis and direct measurement, with and without tensioned bow hair. Such computations are used with analytic models to model the admittance presented to the stretched bow hairs at the ends of the bow and to the string at the point of contact with the bow. Finite element computations are also used to demonstrate the influence of the lowest stick mode vibrations on the low frequency bouncing modes, when the hand-held bow is pressed against the string. The possible influence of the dynamic stick modes on the sound of the bowed instrument is briefly discussed. PMID:22559386

  3. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  4. Violin bow vibrations.

    PubMed

    Gough, Colin E

    2012-05-01

    The modal frequencies and bending mode shapes of a freely supported tapered violin bow are investigated by finite element analysis and direct measurement, with and without tensioned bow hair. Such computations are used with analytic models to model the admittance presented to the stretched bow hairs at the ends of the bow and to the string at the point of contact with the bow. Finite element computations are also used to demonstrate the influence of the lowest stick mode vibrations on the low frequency bouncing modes, when the hand-held bow is pressed against the string. The possible influence of the dynamic stick modes on the sound of the bowed instrument is briefly discussed.

  5. Vibration dose, disturbance stage, and examination results and subjective symptoms in vibration syndrome.

    PubMed

    Yamada, S; Sakakibara, H; Futatsuka, M

    1995-03-01

    The 1973 national survey of 461 chainsaw operators in private forests was reexamined with respect to vibration exposure dose and the Stockholm Workshop Scale (CIRP and SN stages). Vibration dose (VD) was calculated by the formula "ahw(eq.4h) x D (days) x Y (years)". Vibration dose index (VDI) was calculated according to the level of VD. Subjects were divided into five VDI, for CIRP stage, and four SN stage groups. Examination results and prevalence of subjective symptoms were compared between VDI-1 and other VDI groups, CIRP-0 and other CIRP groups, and SN-0 and other SN groups. VD had higher values in CIRP-2 and 3, and SN-2 and 3 than CIRP-0 and SN-0, respectively. The most severe CIRP-3 and SN-3 appeared at higher rate in VDI-4 and 5 groups than in VDI-1 group. VDI had a correlation with mean value of prevalence of CIRP, vibrotactile perception, mean SN stage and fingertip pinch strength. A correlation was observed between skin temperature and CIRP stage, and between vibrotactile perception and SN stage. Decrease of muscle strength and difficulty in fine finger movement were associated with severe sensorineural disturbance.

  6. Vibration budget for observatory equipment

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.; Thompson, Hugh

    2015-07-01

    Vibration from equipment mounted on the telescope and in summit support buildings has been a source of performance degradation at existing astronomical observatories, particularly for adaptive optics performance. Rather than relying only on best practices to minimize vibration, we present here a vibration budget that specifies allowable force levels from each source of vibration in the observatory (e.g., pumps, chillers, cryocoolers, etc.). This design tool helps ensure that the total optical performance degradation due to vibration is less than the corresponding error budget allocation and is also useful in design trade-offs, specifying isolation requirements for equipment, and tightening or widening individual equipment vibration specifications as necessary. The vibration budget relies on model-based analysis of the optical consequences that result from forces applied at different locations and frequencies, including both image jitter and primary mirror segment motion. We develop this tool here for the Thirty Meter Telescope but hope that this approach will be broadly useful to other observatories, not only in the design phase, but for verification and operations as well.

  7. Tissue vibration in prolonged running.

    PubMed

    Friesenbichler, Bernd; Stirling, Lisa M; Federolf, Peter; Nigg, Benno M

    2011-01-01

    The impact force in heel-toe running initiates vibrations of soft-tissue compartments of the leg that are heavily dampened by muscle activity. This study investigated if the damping and frequency of these soft-tissue vibrations are affected by fatigue, which was categorized by the time into an exhaustive exercise. The hypotheses were tested that (H1) the vibration intensity of the triceps surae increases with increasing fatigue and (H2) the vibration frequency of the triceps surae decreases with increasing fatigue. Tissue vibrations of the triceps surae were measured with tri-axial accelerometers in 10 subjects during a run towards exhaustion. The frequency content was quantified with power spectra and wavelet analysis. Maxima of local vibration intensities were compared between the non-fatigued and fatigued states of all subjects. In axial (i.e. parallel to the tibia) and medio-lateral direction, most local maxima increased with fatigue (supporting the first hypothesis). In anterior-posterior direction no systematic changes were found. Vibration frequency was minimally affected by fatigue and frequency changes did not occur systematically, which requires the rejection of the second hypothesis. Relative to heel-strike, the maximum vibration intensity occurred significantly later in the fatigued condition in all three directions. With fatigue, the soft tissue of the triceps surae oscillated for an extended duration at increased vibration magnitudes, possibly due to the effects of fatigue on type II muscle fibers. Thus, the protective mechanism of muscle tuning seems to be reduced in a fatigued muscle and the risk of potential harm to the tissue may increase. PMID:20846656

  8. The association between vibration and vascular injury in rheumatic diseases: a review of the literature.

    PubMed

    Wang, Yu-Jie; Huang, Xiao-Lei; Yan, Jun-Wei; Wan, Ya-Nan; Wang, Bing-Xiang; Tao, Jin-Hui; Chen, Bing; Li, Bao-Zhu; Yang, Guo-Jun; Wang, Jing

    2015-02-01

    Vascular manifestations can be seen early in the pathogenesis of inflammatory rheumatic diseases. Animal experiments, laboratory and clinical findings indicated that acute or long-term vibration exposure can induce vascular abnormalities. Recent years, in addition to Raynaud's phenomenon (RP), vibration as a risk factor for other rheumatic diseases has also received corresponding considered. This review is concentrated upon the role of vibration in the disease of systemic sclerosis (SSc). In this review, we are going to discuss the main mechanisms which are thought to be important in pathophysiology of vascular injury under the three broad headings of "vascular", "neural" and "intravascular". Aspects on the vibration and vascular inflammation are briefly discussed. And the epidemiological studies related to vibration studies in SSc and other rheumatic diseases are taken into account.

  9. Effect of whole body vibration on stereotypy of young children with autism

    PubMed Central

    Bressel, Eadric; Gibbons, Mandi W; Samaha, Andrew

    2011-01-01

    The objective of this case was report on the effects of acute whole body vibration exposure on stereotyped behaviour of young children with autism. Four young boys (ages 4–5 years) diagnosed with autism participated. The children were participants in an early intensive behavioural intervention clinic and during downtimes stood on a whole body vibration platform with the machine turned off (control condition) and on (treatment condition) for three to four, 30 s periods (frequency=28 Hz; amplitude 0.97 mm). The outcome measure was frequency of stereotypic behaviour, which was evaluated for 5 min before and after standing on the vibration platform. The results revealed that whole body vibration was not able to uniformly decrease the rates of all types of stereotypy; that is, some stereotypy decreased while others were unchanged. Subjectively, the children enjoyed whole body vibration which was easy to integrate into the behavioural programme. PMID:22696626

  10. Military Exposures

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... for Providers Diagnosis and Treatment of Exposure Health Effects More Provider Resources » return to top Get Email ...

  11. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, Franklin D.; Middlebrooks, Willis B.; DeMario, Edmund E.

    1994-01-01

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube.

  12. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, F.D.; Middlebrooks, W.B.; DeMario, E.E.

    1994-10-18

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels is disclosed. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube. 14 figs.

  13. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure....

  14. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure....

  15. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure....

  16. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.819 Section 178.819... Testing of IBCs § 178.819 Vibration test. (a) General. The vibration test must be conducted for the... vibration test. (b) Test method. (1) A sample IBC, selected at random, must be filled and closed as...

  17. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure....

  18. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure....

  19. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure....

  20. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components...

  1. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure....

  2. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  3. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure....

  4. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure....

  5. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components...

  6. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure....

  7. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  8. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  9. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  10. Effects of Short-Period Whole-Body Vibration of 20 Hz on Selected Blood Biomarkers in Wistar Rats.

    PubMed

    Monteiro, Milena de Oliveira Bravo; de Sá-Caputo, Danúbia da Cunha; Carmo, Fernanda Santos do; Bernardo, Raquel Mattos; Pacheco, Raphaelle; Arnóbio, Adriano; Guimarães, Carlos Alberto Sampaio; Bernardo, Luciana Camargo; Santos-Filho, Sebastião David; Asad, Nasser Ribeiro; Unger, Marianne; Marin, Pedro Jesus; Bernardo-Filho, Mario

    2015-08-31

    There is a growing interest in the use of vibration generated by oscillating/vibratory platforms - also known as whole-body vibration (WBV) - for achieving therapeutic, preventative and/or physical performance goals. This study investigated the effects of vibration generated by an oscillating platform on the concentration of blood biomarkers in rats. Wistar rats (n = 8) were divided in 2 groups, sedated and individually positioned on an oscillating platform. The experimental group (EG) was subjected to vibrations of 20 Hz for one min per day for one week while the control group (CG) experienced no vibration. Samples of heparinized whole blood were drawn by cardiac puncture for biochemical analysis. Concentrations of total cholesterol, triglycerides, HDL, LDL, VLDL, glucose, CK, albumin, alkaline phosphates, TGP, TGO, γGT, lipase, amylase, urea and creatinine were determined. White blood cell count and a platelet hemogram were also performed. Following seven sessions of exposure to the vibration, a significant (P < 0.05) reduction in γGT, VLDL and leukocytes was found. A weekly 1-min/day exposure of 20 Hz vibration can was shown to alter the concentrations of selected blood biomarkers in rats. The action mechanism associated with these effects seems highly complex, but the findings might contribute to the understanding of these mechanisms related to the exposure to 20 Hz vibration. PMID:26211644

  11. An iOS Application for Evaluating Whole-body Vibration Within a Workplace Risk Management Process.

    PubMed

    McGlothlin, James; Burgess-Limerick, R; Lynas, D

    2015-01-01

    Workplace management of whole-body vibration exposure requires systematic collection of whole-body vibration data in conjunction with the numerous variables which influence vibration amplitudes. The cost and complexity of commercially available measurement devices is an impediment to the routine collection of such data by workplaces. An iOS application (WBV) has been developed which allows an iPod Touch to be used to measure whole-body vibration exposures. The utility of the application was demonstrated by simultaneously obtaining 98 pairs of whole-body vibration measurements from both the iPod Touch application and a commercially available whole-body vibration device during the operation of a variety of vehicles and mobile plant in operation at a surface coal mine. The iOS application installed on a fifth-generation iPod Touch was shown to provide a 95% confidence of +/- 0.077 m/s(2) r.m.s. constant error for the vertical direction. Situations in which vibration levels lay within the ISO2631.1 health guidance caution zone were accurately identified, and the qualitative features of the frequency spectra were reproduced. The low cost and relative simplicity of the application has potential to facilitate its use as a screening tool to identify situations in which musculoskeletal disorders may arise as a consequence of exposure to whole-body vibration.

  12. Effects of Short-Period Whole-Body Vibration of 20 Hz on Selected Blood Biomarkers in Wistar Rats.

    PubMed

    Monteiro, Milena de Oliveira Bravo; de Sá-Caputo, Danúbia da Cunha; Carmo, Fernanda Santos do; Bernardo, Raquel Mattos; Pacheco, Raphaelle; Arnóbio, Adriano; Guimarães, Carlos Alberto Sampaio; Bernardo, Luciana Camargo; Santos-Filho, Sebastião David; Asad, Nasser Ribeiro; Unger, Marianne; Marin, Pedro Jesus; Bernardo-Filho, Mario

    2015-08-31

    There is a growing interest in the use of vibration generated by oscillating/vibratory platforms - also known as whole-body vibration (WBV) - for achieving therapeutic, preventative and/or physical performance goals. This study investigated the effects of vibration generated by an oscillating platform on the concentration of blood biomarkers in rats. Wistar rats (n = 8) were divided in 2 groups, sedated and individually positioned on an oscillating platform. The experimental group (EG) was subjected to vibrations of 20 Hz for one min per day for one week while the control group (CG) experienced no vibration. Samples of heparinized whole blood were drawn by cardiac puncture for biochemical analysis. Concentrations of total cholesterol, triglycerides, HDL, LDL, VLDL, glucose, CK, albumin, alkaline phosphates, TGP, TGO, γGT, lipase, amylase, urea and creatinine were determined. White blood cell count and a platelet hemogram were also performed. Following seven sessions of exposure to the vibration, a significant (P < 0.05) reduction in γGT, VLDL and leukocytes was found. A weekly 1-min/day exposure of 20 Hz vibration can was shown to alter the concentrations of selected blood biomarkers in rats. The action mechanism associated with these effects seems highly complex, but the findings might contribute to the understanding of these mechanisms related to the exposure to 20 Hz vibration.

  13. The effects of low-frequency vibrations on hepatic profile of blood

    NASA Astrophysics Data System (ADS)

    Damijan, Z.

    2008-02-01

    Body vibrations training has become popular in sports training, fitness activity, it is still a rare form of physical rehabilitation.. Vibrations are transmitted onto the whole body or some body parts of an exercising person via a vibration platform subjected to mechanical vertical vibrations. During the training session a participant has to maintain his body position or do exercises that engage specific muscles whilst vibrations of the platform are transmitted onto the person's body. This paper is the continuation of the earlier study covering the effects of low-frequency vibrations on selected physiological parameters of the human body. The experiments were conducted to find the answer to the question if vibration exposure (total duration of training sessions 6 hours 20 min) should produce any changes in hepatic profile of blood. Therefore a research program was undertaken at the University of Science and Technology AGH UST to investigate the effects of low-frequency vibration on selected parameters of hepatic profile of human blood. Cyclic fluctuations of bone loading were induced by the applied harmonic vibration 3.5 Hz and amplitude 0.004 m. The experiments utilizing two vibrating platforms were performed in the Laboratory of Structural Acoustics and Biomedical Engineering AGH-UST. The applied vibrations were harmless and not annoying, in accordance with the standard PN-EN ISO 130901-1, 1998. 23 women volunteers had 19 sessions on subsequent working days, at the same time of day. during the tests the participants remained in the standing position, passive. The main hypothesis has it that short-term low-frequency vibration exposure might bring about the changes of the hepatic profile of blood, including: bilirubin (BILIRUBIN), alkaline phosphatase (Alp), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin (ALBUMIN) levels. Research data indicate the low-frequency vibrations exposure produces statistically significant decrease of

  14. Airfoil Vibration Dampers program

    NASA Technical Reports Server (NTRS)

    Cook, Robert M.

    1991-01-01

    The Airfoil Vibration Damper program has consisted of an analysis phase and a testing phase. During the analysis phase, a state-of-the-art computer code was developed, which can be used to guide designers in the placement and sizing of friction dampers. The use of this computer code was demonstrated by performing representative analyses on turbine blades from the High Pressure Oxidizer Turbopump (HPOTP) and High Pressure Fuel Turbopump (HPFTP) of the Space Shuttle Main Engine (SSME). The testing phase of the program consisted of performing friction damping tests on two different cantilever beams. Data from these tests provided an empirical check on the accuracy of the computer code developed in the analysis phase. Results of the analysis and testing showed that the computer code can accurately predict the performance of friction dampers. In addition, a valuable set of friction damping data was generated, which can be used to aid in the design of friction dampers, as well as provide benchmark test cases for future code developers.

  15. Vibrational spectroscopy of stichtite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Erickson, Kristy L.

    2004-11-01

    Raman spectroscopy complimented with infrared spectroscopy has been used to study the mineral stitchtite, a hydrotalcite of formula Mg 6Cr 2(CO 3)(OH) 16·4H 2O. Two bands are observed at 1087 and 1067 cm -1 with an intensity ratio of ˜2.5/1 and are attributed to the symmetric stretching vibrations of the carbonate anion. The observation of two bands is attributed to two species of carbonate in the interlayer, namely weakly hydrogen bonded and strongly hydrogen bonded. Two infrared bands are found at 1457 and 1381 cm -1 and are assigned to the antisymmetric stretching modes. These bands were not observed in the Raman spectrum. Two infrared bands are observed at 744 and 685 cm -1 and are assigned to the ν4 bending modes. Two Raman bands were observed at 539 and 531 cm -1 attributed to the ν2 bending modes. Importantly the band positions of the paragenically related hydrotalcites stitchtite, iowaite, pyroaurite and reevesite all of which contain the carbonate anion occur at different wavenumbers. Consequently, Raman spectroscopy can be used to distinguish these minerals, particularly in the field where many of these hydrotalcites occur simultaneously in ore zones.

  16. Smart accelerometer. [vibration damage detection

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    The invention discloses methods and apparatus for detecting vibrations from machines which indicate an impending malfunction for the purpose of preventing additional damage and allowing for an orderly shutdown or a change in mode of operation. The method and apparatus is especially suited for reliable operation in providing thruster control data concerning unstable vibration in an electrical environment which is typically noisy and in which unrecognized ground loops may exist.

  17. Temporomandibular joint vibration in bruxers.

    PubMed

    Li, Xueling; Lin, Xuefeng; Wang, Yan

    2009-07-01

    Temporomandibular joint vibration is considered an important physical sign of joint dysfunction and/or joint pathology. The aim of this study was to compare the difference of joint vibration between bruxers and asymptomatic individuals, evaluate the effect of bruxism on the temporomandibular joint (TMJ) and the association between bruxism and temporomandibular disorders. Twenty-four (24) bruxers and 16 asymptomatic subjects were included in the study. Bilateral joint vibrations with jaw tracking were recorded using a TMJ detecting instrument during rhythmic jaw opening and closing movement. The results showed that the vibratory energy and amplitude of the moderate to severe bruxers were significantly higher than that of the mild bruxers and asymptomatic subjects. The percentage of joint vibration occurrence in asymptomatic subjects, mild bruxers, and moderate to severe bruxers was 75.0%, 77.8%, and 100%, respectively. It was concluded that bruxism might induce abnormal joint vibrations, and that the energy of abnormal vibrations might increase with the degree of bruxism.

  18. Rhodopsin photochemistry is vibrationally coherent

    SciTech Connect

    Mathies, R.A.; Wang, Q.; Peteanu, L.A.

    1995-12-31

    Visual excitation is initiated by the absorption of a photon by the 11-cis retinal chromophore bound within the pigment called rhodopsin. We have used a variety of vibrational spectroscopies to obtain information about the vibrational nuclear dynamics that lead to this efficient photochemical isomerization. The cis-trans isomerization in rhodopsin is complete in only 200 fs. The extreme speed of this process, which is consistent with the {approximately}50 fs lifetime indicated by the spontaneous emission yield, suggests that the photochemistry involves non-stationary states or vibrational coherence. Recent studies have in fact observed vibrationally coherent oscillations of the ground state photoproduct called bathorhodopsin following impulsive excitation of the rhodopsin reactant. This conclusively demonstrates that the isomerization process in rhodopsin is vibrationally coherent. These observations further suggest that the isomerization quantum yield is directly dependent on the excited-state torsional velocity and can be thought of as a Landau-Zener tunneling process. This work establishes a vibrationally coherent paradigm for the photochemistry of vision that may be relevant for many other photochemical and photobiological processes including photosynthesis and proton pumping in bacteriorhodopsin.

  19. Vibrational lifetimes of hydrated phospholipids

    NASA Astrophysics Data System (ADS)

    Jadidi, Tayebeh; Anvari, Mehrnaz; Mashaghi, Alireza; Sahimi, Muhammad; Rahimi Tabar, M. Reza

    2013-04-01

    Large-scale ab initio molecular-dynamics simulations have been carried out to compute, at human-body temperature, the vibrational modes and lifetimes of pure and hydrated dipalmitoylphosphatidylcholine (DPPC) lipids. The projected atomic vibrations calculated from the spectral energy density are used to compute the vibrational modes and the lifetimes. All the normal modes of the pure and hydrated DPPC and their frequencies are identified. The computed lifetimes incorporate the full anharmonicity of the atomic interactions. The vibrational modes of the water molecules close to the head group of DPPC are active (possess large projected spectrum amplitudes) in the frequency range 0.5-55 THz, with a peak at 2.80 THz in the energy spectrum. The computed lifetimes for the high-frequency modes agree well with the recent data measured at room temperature where high-order phonon scattering is not negligible. The computed lifetimes of the low-frequency modes can be tested using the current experimental capabilities. Moreover, the approach may be applied to other lipids and biomolecules, in order to predict their vibrational dispersion relations, and to study the dynamics of vibrational energy transfer.

  20. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    NASA Astrophysics Data System (ADS)

    De Greef, Daniël; Dirckx, Joris J. J.

    2014-05-01

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without compromising

  1. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    SciTech Connect

    De Greef, Daniël; Dirckx, Joris J. J.

    2014-05-27

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without compromising

  2. The effect of whole-body resonance vibration in a porcine model of spinal cord injury.

    PubMed

    Streijger, Femke; Lee, Jae H T; Chak, Jason; Dressler, Dan; Manouchehri, Neda; Okon, Elena B; Anderson, Lisa M; Melnyk, Angela D; Cripton, Peter A; Kwon, Brian K

    2015-06-15

    Whole-body vibration has been identified as a potential stressor to spinal cord injury (SCI) patients during pre-hospital transportation. However, the effect that such vibration has on the acutely injured spinal cord is largely unknown, particularly in the frequency domain of 5 Hz in which resonance of the spine occurs. The objective of the study was to investigate the consequences of resonance vibration on the injured spinal cord. Using our previously characterized porcine model of SCI, we subjected animals to resonance vibration (5.7±0.46 Hz) or no vibration for a period of 1.5 or 3.0 h. Locomotor function was assessed weekly and cerebrospinal fluid (CSF) samples were collected to assess different inflammatory and injury severity markers. Spinal cords were evaluated histologically to quantify preserved white and gray matter. No significant differences were found between groups for CSF levels of monocyte chemotactic protein-1, interleukin 6 (IL-6) and lL-8. Glial fibrillary acidic protein levels were lower in the resonance vibration group, compared with the non-vibrated control group. Spared white matter tissue was increased within the vibrated group at 7 d post-injury but this difference was not apparent at the 12-week time-point. No significant difference was observed in locomotor recovery following resonance vibration of the spine. Here, we demonstrate that exposure to resonance vibration for 1.5 or 3 h following SCI in our porcine model is not detrimental to the functional or histological outcomes. Our observation that a 3.0-h period of vibration at resonance frequency induces modest histological improvement at one week post-injury warrants further study.

  3. Experimental characterization of a nonlinear vibration absorber using free vibration

    NASA Astrophysics Data System (ADS)

    Tang, Bin; Brennan, M. J.; Gatti, G.; Ferguson, N. S.

    2016-04-01

    Knowledge of the nonlinear characteristics of a vibration absorber is important if its performance is to be predicted accurately when connected to a host structure. This can be achieved theoretically, but experimental validation is necessary to verify the modelling procedure and assumptions. This paper describes the characterization of such an absorber using a novel experimental procedure. The estimation method is based on a free vibration test, which is appropriate for a lightly damped device. The nonlinear absorber is attached to a shaker which is operated such that the shaker works in its mass-controlled regime, which means that the shaker dynamics, which are also included in the measurement, are considerably simplified, which facilitates a simple estimation of the absorber properties. From the free vibration time history, the instantaneous amplitude and instantaneous damped natural frequency are estimated using the Hilbert transform. The stiffness and damping of the nonlinear vibration absorber are then estimated from these quantities. The results are compared with an analytical solution for the free vibration of the nonlinear system with cubic stiffness and viscous damping, which is also derived in the paper using an alternative approach to the conventional perturbation methods. To further verify the approach, the results are compared with a method in which the internal forces are balanced at each measured instant in time.

  4. Noise and vibration ride comfort criteria

    NASA Technical Reports Server (NTRS)

    Dempsey, T. K.; Leatherwood, J. D.; Clevenson, S. A.

    1976-01-01

    Two of the most important factors, namely, vibration and noise, were studied to (1) determine whether composite or separate noise and vibration criteria are needed for the prediction of ride quality, (2) determine a noise correction for the previously-defined vibration criteria of the ride quality model, (3) assess whether these noise corrections depend on the nature of the vibration stimuli, i.e., deterministic as opposed to random, and (4) specify noise-vibration criteria for this combined environment. The stimuli for the study consisted of octave bands of noise centered at 500 or 2,000 Hz and vertical vibrations composed of either 5 Hz sinusoidal vibration or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. The noise stimuli were presented at levels ranging from ambient to 95 dB(A) and the vibrations at levels ranging from 0.02 to 0.13g rms.

  5. Calibration of Sound and Vibration Sensors and Vibration Testing Systems

    NASA Astrophysics Data System (ADS)

    Nicklich, H.

    2004-08-01

    SPEKTRA is a manufacturer of high quality calibration systems for sound and vibration. Under license No DKD-K-27801, a calibration lab was established at SPEKTRA to provide a calibration service. The paper gives a summary of 4 years experience in the calibration of vibration Sensors, measuring systems and vibration test equipment in the industrial field. In practice calibration is often treated as an unpleasant job that is solved by handing out a "Calibration certificate of every part of the system" to the Quality Manager. The paper comes to the conclusion that calibration can help to minimize costs and risks if the customer has basic knowledge in international standards, the used test equipment and the special requirements for testing with this configuration. It is not enough to calibrate one sen- sor of a system in a standard range. The requirements for calibration should be defined individually for every testing system and application.

  6. Calibration of sound and vibration sensors and vibration testing systems

    NASA Astrophysics Data System (ADS)

    Nicklich, Holger

    2004-08-01

    SPEKTRA is a manufacturer of high quality calibration systems for sound and vibration. Under license No DKD-K-27801, a calibration lab was established at SPEKTRA to provide a calibration service. The paper gives a summary of 4 years experience in the calibration of vibration Sensors, measuring systems and vibration test equipment in the industrial field. In practice calibration is often treated as an unpleasant job that is solved by handing out a “Calibration certificate of every part of the system” to the Quality Manager. The paper comes to the conclusion that calibration can help to minimize costs and risks if the customer has basic knowledge in international standards, the used test equipment and the special requirements for testing with this configuration. It is not enough to calibrate one sensor of a system in a standard range. The requirements for calibration should be defined individually for every testing system and application.

  7. Analysis of railway track vibration

    NASA Astrophysics Data System (ADS)

    Ono, K.; Yamada, M.

    1989-04-01

    Analytical formulae are developed for estimating the amplitudes of the vibrations generated in railway tracks by wheels and rail discontinuities or by unevennesses on their surfaces. Rails are assumed to be supported elastically on concrete sleepers by resilient rail-pads inserted between them. The elasticities and the masses of track materials and those of the roadbed are also taken into consideration. It is shown that after an impulse is applied to the track, not only is a vibration with a comparatively low natural frequency generated, but also traveling waves with higher frequencies, and the latter propagate lengthwise along the track or downwards into the roadbed. With the assumption that the power spectral density of the unevennesses on the rail surface is in proportion to the third power of the wavelength, or to (wavenumber) -3, the amplitudes of the vibrations in railway tracks supported by rail-pads and roadbeds with various magnitudes of elastic constants are analyzed and the values for each one-third octave band are estimated. The velocity of the vibration takes on a maximum value for the band with a center frequency of 63 Hz, which corresponds to the resonant frequency of the system composed of the wheel and the track. As the frequency increases beyond this value, the velocity of the vibration takes on a second maximum value at a frequency of about 1000 Hz. These estimates are compared with the data obtained from field measurements and reasonably good correlations are found between them.

  8. Jamming in Vibrated Granular Systems

    NASA Astrophysics Data System (ADS)

    Utter, Brian

    2009-03-01

    Granular materials exist all around us, from avalanches in nature to the mixing of pharmaceuticals, yet the behavior of these``fluids'' is poorly understood. Their flow can be characterized by the continuous forming and breaking of a strong force network resisting flow. This jamming/unjamming behavior is typical of a variety of systems, including granular flows, and is influenced by factors such as grain packing fraction, applied shear stress, and the random kinetic energy of the particles. I'll present experiments on quasi-static shear and free-surface granular flows under the influence of external vibrations. By using photoelastic grains, we are able to measure both particle trajectories and the local force network in these 2D flows. We find through particle tracking that dense granular flow is composed of comparable contributions from the mean flow, affine, and non-affine deformations. During shear, sufficient external vibration weakens the strong force network and reduces the amount of flow driven by sidewalls. In a rotating drum geometry, large vibrations induce failure as might be expected, while small vibration leads to strengthening of the pile. The avalanching behavior is also strongly history dependent, as evident when the rotating drum is driven in an oscillatory motion, and we find that sufficient vibration erases the memory of the pile. These results point to the central role of the mobilization of friction in quasi-static granular flow.

  9. Non-resonant vibration conversion

    NASA Astrophysics Data System (ADS)

    Spreemann, D.; Manoli, Y.; Folkmer, B.; Mintenbeck, D.

    2006-09-01

    The development of distributed wireless sensor systems for automotive, medical or industrial monitoring applications is one of the aims for MEMS technology. For applications where environmental vibrations are present, the harvesting of this kinetic energy is an opportunity to power remote sensor nodes. For the conversion, typically resonant spring-mass-damper systems are considered. In this paper, a novel non-resonant conversion mechanism is presented. Depending on the geometry of the harvester and the vibration, this conversion mechanism shows a few advantages: low frequencies can be converted, higher or lower modes of vibration will be converted instantaneously, the transducer has 2 DOF for energy conversion and the generation of energy is not limited to a small frequency band. Based on a vibration amplitude of 100 µm, the behavior of a fine-mechanical generator and a MEMS generator has been simulated. The results of the fine-mechanical generator were verified by measurements of a prototype with 1.5 cm3 volume. So far the transducer is capable of producing 0.4-3 mW for vibration frequencies ranging from 30 to 80 Hz.

  10. A comparison of different vibration exercise techniques on neuromuscular performance.

    PubMed

    García-Gutiérrez, M T; Rhea, M R; Marín, P J

    2014-09-01

    The first purpose of this study was to determine the effects of whole-body vibration (WBV) exercise during an isometric hand-grip exercise. The second purpose was to evaluate whether more than one vibratory focus would evoke an increase in the effects evoked by only one vibratory focus. The present study investigated whether WBV exposure during 10 repetitions of a handgrip dynamometer while standing on a WBV platform. Twenty-eight recreationally active university students completed 3 different test conditions, in random order: 1) grip dynamometer exercise with superimposed WBV and contralateral arm vibration (WBV+AV); 2) superimposed arm vibration only (AV); 3) grip dynamometer exercise without vibration (Control). The hand grip strength was slightly higher in the WBV condition as compared to the Control and AV conditions (1.1% and 3.6%, p>0.05, respectively). A main effect of the EMGrms of extensor digitorum muscle (ED) was observed indicating that the WBV+AV condition produced a lower co-activation of ED during a flexor digital task than the Control and AV (p<0.05) conditions. The application of WBV+AV may acutely increase muscle coordination and decreases the coactivation of ED. Furthermore, the muscle EMGrms showed increases in activation near the vibratory focus in both upper- and lower-body.

  11. Comparing three methods for evaluating impact wrench vibration emissions.

    PubMed

    McDowell, Thomas W; Marcotte, Pierre; Warren, Cristopher; Welcome, Daniel E; Dong, Ren G

    2009-08-01

    To provide a means for comparing impact wrenches and similar tools, the international standard ISO 8662-7 prescribes a method for measuring the vibrations at the handles of tools during their operations against a cotton-phenolic braking device. To improve the standard, alternative loading mechanisms have been proposed; one device comprises aluminum blocks with friction brake linings, while another features plate-mounted bolts to provide the tool load. The objective of this study was to evaluate these three loading methods so that tool evaluators can select appropriate loading devices in order to obtain results that can be applied to their specific workplace operations. Six experienced tool operators used five tool models to evaluate the loading mechanisms. The results of this study indicate that different loads can yield different tool comparison results. However, any of the three devices appears to be adequate for initial tool screenings. On the other hand, vibration emissions measured in the laboratory are unlikely to be fully representative of those in the workplace. Therefore, for final tool selections and for reliably assessing workplace vibration exposures, vibration measurements should be collected under actual working conditions. Evaluators need to use appropriate numbers of tools and tool operators in their assessments; recommendations are provided.

  12. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-08-31

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.

  13. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-10-13

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed. The month of June, 2004 was primarily occupied with the writing of the Phase I Final Report, the sole deliverable of Phase I, which will be submitted in the next quarter. Redesign of the laboratory prototype and design of the downhole (Phase II) prototype was begun.

  14. Handheld vibration effects shoulder motion.

    PubMed

    Tripp, B L; Eberman, L E; Dwelly, P M

    2009-12-01

    We explored effects of handheld vibration on glenohumeral motion in competitive overhead-throwing athletes. We used a randomized, blinded pre-test post-test cross-over design. Each arm of each subject experienced 2 conditions (1-control, 1-experimental), each with pre-test and post-test measures; the order of which was randomized. Participants included Division-I baseball and softball players (n=35: age=20+/-2 yr, height=178+/-9 cm, mass=84+/-12 kg, years of sport participation=13+/-4 yrs). During the experimental condition, participants held a vibrating (2.2 mm, 15 Hz, 20 s), 2.55 kg (5.62 lbs) Mini-VibraFlex dumbbell (Orthometric, New York, NY) in neutral glenohumeral rotation. During the control condition, participants held the still dumbbell (0 mm, 0 Hz, 20 s). Participants rested one min after each trial (3). We used a digital protractor to assess range of motion bilaterally, employing a standard technique for measuring maximal internal (IR) and external rotation (ER). Repeated-measures analyses of variance indicated that range of dominant IR increased 6.8% ( P=0.001, ES=0.16) after handheld vibration. Handheld vibration did not affect range of dominant ER ( P>0.05, 1-beta=0.20), non-dominant IR ( P>0.05, 1-beta=0.41), or non-dominant ER ( P>0.05, 1-beta=0.05). Short bouts of handheld vibration increased dominant IR in collegiate baseball and softball athletes. These results suggest that handheld vibration may help maintain glenohumeral IR that is vital to the healthy and competitive throwing shoulder.

  15. Whole-body vibration and ergonomic study of US railroad locomotives

    NASA Astrophysics Data System (ADS)

    Johanning, Eckardt; Landsbergis, Paul; Fischer, Siegfried; Christ, Eberhard; Göres, Benno; Luhrman, Raymond

    2006-12-01

    US locomotive operators have exposure to multi-axis whole-body vibration (WBV) and shocks while seated. This study assessed operator-related and ergonomic seating design factors that may have confounding or mitigating influence on WBV exposure and its effects. Vibration exposure was measured according to international guidelines (ISO 2631-1; 1997); ergonomic work place factors and vibration effects were studied with a cross-sectional survey instrument distributed to a randomly selected group of railroad engineers ( n=2546) and a control group; and during vehicle inspections. The survey response rate was 47% for the RR engineers ( n=1195) and 41% for the controls ( n=323). Results of the mean basic vibration measurements were for the x, y, z-direction and vector sum 0.14, 0.22, 0.28 and 0.49 m/s 2 respectively; almost all crest factors (CF), MTVV and VDV values were above the critical ratios given in ISO 2631-1. The prevalence of serious neck and lower back disorders among locomotive engineers was found to be nearly double that of the sedentary control group without such exposure. Railroad engineers rated their seats mostly unacceptable regarding different adjustment and comfort aspects (3.02-3.51; scale 1=excellent to 4=unacceptable), while the control group rated their chairs more favorably (1.96-3.44). Existing cab and seat design in locomotives can result in prolonged forced awkward spinal posture of the operator combined with WBV exposure. In a logistic regression analysis, time at work being bothered by vibration (h/day) was significantly associated with an increased risk of low back pain, shoulder and neck pain, and sciatic pain among railroad engineers. Customized vibration attenuation seats and improved cab design of the locomotive controls should be further investigated.

  16. [Raman active vibrations of aluminosilicates].

    PubMed

    Pan, Feng; Yu, Xue-hui; Mo, Xuan-xue; You, Jing-lin; Wang, Chen; Chen, Hui; Jiang, Guo-chang

    2006-10-01

    Raman spectra of aluminosilicate minerals, namely kyanite, andalusite, and sillimanite and K2O-Al2O3-SiO2 glasses were recorded. Four alumino-silicon tetrahedral model clusters were calculated by self-consistent (SCF) molecular orbital ab-ini-tio calculation of the quantum chem (QC) method. The result shows a decrease tendency in Raman frequencies in the 800-1200 cm(-1) frequency region with increase in four-coordinated Al content, which is assigned to the Si--Onb symmetry stretching vibrations. The Raman spectra in the 700-800 cm(-1) frequency region is attributed to Al-Onb symmetry stretching vibrations. PMID:17205741

  17. Innovative Techniques Simplify Vibration Analysis

    NASA Technical Reports Server (NTRS)

    2010-01-01

    In the early years of development, Marshall Space Flight Center engineers encountered challenges related to components in the space shuttle main engine. To assess the problems, they evaluated the effects of vibration and oscillation. To enhance the method of vibration signal analysis, Marshall awarded Small Business Innovation Research (SBIR) contracts to AI Signal Research, Inc. (ASRI), in Huntsville, Alabama. ASRI developed a software package called PC-SIGNAL that NASA now employs on a daily basis, and in 2009, the PKP-Module won Marshall s Software of the Year award. The technology is also used in many industries: aircraft and helicopter, rocket engine manufacturing, transportation, and nuclear power."

  18. [Raman active vibrations of aluminosilicates].

    PubMed

    Pan, Feng; Yu, Xue-hui; Mo, Xuan-xue; You, Jing-lin; Wang, Chen; Chen, Hui; Jiang, Guo-chang

    2006-10-01

    Raman spectra of aluminosilicate minerals, namely kyanite, andalusite, and sillimanite and K2O-Al2O3-SiO2 glasses were recorded. Four alumino-silicon tetrahedral model clusters were calculated by self-consistent (SCF) molecular orbital ab-ini-tio calculation of the quantum chem (QC) method. The result shows a decrease tendency in Raman frequencies in the 800-1200 cm(-1) frequency region with increase in four-coordinated Al content, which is assigned to the Si--Onb symmetry stretching vibrations. The Raman spectra in the 700-800 cm(-1) frequency region is attributed to Al-Onb symmetry stretching vibrations.

  19. The vibrations of hand bells

    NASA Astrophysics Data System (ADS)

    Kelby, S. D.; Middleton, R. P.

    1980-09-01

    In spite of the fact that the bell is one of the oldest and simplest of all musical instruments, the manner in which bells produce their characteristic sound is little studied. With the aid of relatively simple techniques, however, it is possible to provide an effective and informative demonstration of the ways in which bells vibrate. The theoretical predictions made regarding the modes of vibration can be verified and applied to the problem of eliminating 'warble'-the undesirable periodic variation of amplitude of the sound produced by the bell.

  20. Localized vibrations of graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Savin, A. V.; Kivshar, Yu. S.

    2016-08-01

    Vibrational modes of graphene nanoribbons are studied. It is demonstrated that in an unstretched graphene nanoribbon, localized vibrations (in the form of breathers) can occur only at the edges. The largest number of localized edge oscillations is expected for the nanoribbons with the armchair structure. Stretching of a nanoribbon can lead to the appearance of new types of strongly localized oscillations. When a nanoribbon is stretched, in its oscillatory spectrum a frequency gap appears in which the frequencies of the localized modes are located. An armchair nanoribbon can support localized modes only at its edges, while a highly stretched zigzag nanoribbon can support them both at the edges and inside the nanoribbon.

  1. Neurocognitive responses to a single session of static squats with whole body vibration.

    PubMed

    Amonette, William E; Boyle, Mandy; Psarakis, Maria B; Barker, Jennifer; Dupler, Terry L; Ott, Summer D

    2015-01-01

    The purpose of this study was to determine if the head accelerations using a common whole body vibration (WBV) exercise protocol acutely reduced neurocognition in healthy subjects. Second, we investigated differential responses to WBV plates with 2 different delivery mechanisms: vertical and rotational vibrations. Twelve healthy subjects (N = 12) volunteered and completed a baseline (BASE) neurocognitive assessment: the Immediate Postconcussion Assessment and Cognitive Test (ImPACT). Subjects then participated in 3 randomized exercise sessions separated by no more than 2 weeks. The exercise sessions consisted of five 2-minute sets of static hip-width stance squats, with the knees positioned at a 45° angle of flexion. The squats were performed with no vibration (control [CON]), with a vertically vibrating plate (vertical vibration [VV]), and with a rotational vibrating plate (rotational vibration [RV]) set to 30 Hz with 4 mm of peak-to-peak displacement. The ImPACT assessments were completed immediately after each exercise session and the composite score for 5 cognitive domains was analyzed: verbal memory, visual memory, visual motor speed, reaction time, and impulse control. Verbal memory scores were unaffected by exercise with or without vibration (p = 0.40). Likewise, visual memory was not different (p = 0.14) after CON, VV, or RV. Significant differences were detected for visual motor speed (p = 0.006); VV was elevated compared with BASE (p = 0.01). There were no significant differences (p = 0.26) in reaction time or impulse control (p = 0.16) after exercise with or without vibration. In healthy individuals, 10 minutes of 30 Hz, 4-mm peak-to-peak displacement vibration exposure with a 45° angle of knee flexion did not negatively affect neurocognition.

  2. Neurocognitive responses to a single session of static squats with whole body vibration.

    PubMed

    Amonette, William E; Boyle, Mandy; Psarakis, Maria B; Barker, Jennifer; Dupler, Terry L; Ott, Summer D

    2015-01-01

    The purpose of this study was to determine if the head accelerations using a common whole body vibration (WBV) exercise protocol acutely reduced neurocognition in healthy subjects. Second, we investigated differential responses to WBV plates with 2 different delivery mechanisms: vertical and rotational vibrations. Twelve healthy subjects (N = 12) volunteered and completed a baseline (BASE) neurocognitive assessment: the Immediate Postconcussion Assessment and Cognitive Test (ImPACT). Subjects then participated in 3 randomized exercise sessions separated by no more than 2 weeks. The exercise sessions consisted of five 2-minute sets of static hip-width stance squats, with the knees positioned at a 45° angle of flexion. The squats were performed with no vibration (control [CON]), with a vertically vibrating plate (vertical vibration [VV]), and with a rotational vibrating plate (rotational vibration [RV]) set to 30 Hz with 4 mm of peak-to-peak displacement. The ImPACT assessments were completed immediately after each exercise session and the composite score for 5 cognitive domains was analyzed: verbal memory, visual memory, visual motor speed, reaction time, and impulse control. Verbal memory scores were unaffected by exercise with or without vibration (p = 0.40). Likewise, visual memory was not different (p = 0.14) after CON, VV, or RV. Significant differences were detected for visual motor speed (p = 0.006); VV was elevated compared with BASE (p = 0.01). There were no significant differences (p = 0.26) in reaction time or impulse control (p = 0.16) after exercise with or without vibration. In healthy individuals, 10 minutes of 30 Hz, 4-mm peak-to-peak displacement vibration exposure with a 45° angle of knee flexion did not negatively affect neurocognition. PMID:25536489

  3. The influence of whole body vibration on the central and peripheral cardiovascular system.

    PubMed

    Robbins, Dan; Yoganathan, Priya; Goss-Sampson, Mark

    2014-09-01

    The purpose of this study was to investigate the physiological changes of the cardiovascular system in response to whole body vibration during quiet standing and identify whether there is a greater influence on the central or peripheral cardiovascular system. Twenty healthy participants (12 male and 8 female) were assessed over two separate testing sessions for changes in peripheral skin temperature, peripheral venous function, blood flow velocity in the dorsalis pedis artery, blood pressure and heart rate during quiet standing with 40 Hz 1·9 mm synchronous vibration. Vibration exposure totalled 5 min in 1 min increments with 5 min recovery during each testing session. There were no significant changes in heart rate, blood pressure or peripheral skin temperature. Significant results were obtained for blood flow velocity with increases from 0·5 + 0·2 cm·s(-1) at baseline to 1 + 0·2 cm·s(-1) during vibration, returning to baseline levels during the recovery period. Due to the absence of changes in heart rate, blood pressure or lower leg and foot temperature, the change in blood flow velocity can be attributed to changes in peripheral vascular function. The results suggest a high level of sensitivity of the peripheral vascular system to vibration exposure; therefore, further studies should be completed to ascertain the physiological mechanisms underlying the effects of vibration on the peripheral vascular system.

  4. Probing vibrational anisotropy with nuclear resonance vibrational spectroscopy.

    SciTech Connect

    Pavlik, J. W.; Barabanschikov, A.; Oliver, A. G.; Alp, E. E.; Sturhahn, W.; Zhao, J.; Sage, J. T.; Scheidt, W. R.

    2010-06-14

    A NRVS single-crystal study (NRVS=nuclear resonance vibrational spectroscopy) has provided detailed information on the in-plane modes of nitrosyl iron porphyrinate [Fe(oep)(NO)] (see picture; oep=octaethylporphyrin). The axial nitrosyl ligand controls the direction of the in-plane iron motion.

  5. Period of vibration of axially vibrating truly nonlinear rod

    NASA Astrophysics Data System (ADS)

    Cveticanin, L.

    2016-07-01

    In this paper the axial vibration of a muscle whose fibers are parallel to the direction of muscle compression is investigated. The model is a clamped-free rod with a strongly nonlinear elastic property. Axial vibration is described by a nonlinear partial differential equation. A solution of the equation is constructed for special initial conditions by using the method of separation of variables. The partial differential equation is separated into two uncoupled strongly nonlinear second order differential equations. Both equations, with displacement function and with time function are exactly determined. Exact solutions are given in the form of inverse incomplete and inverse complete Beta function. Using boundary and initial conditions, the frequency of vibration is obtained. It has to be mentioned that the determined frequency represents the exact analytic description for the axially vibrating truly nonlinear clamped-free rod. The procedure suggested in this paper is applied for calculation of the frequency of the longissimus dorsi muscle of a cow. The influence of elasticity order and elasticity coefficient on the frequency property is tested.

  6. Vibration analysis by time-average holography

    NASA Technical Reports Server (NTRS)

    Aprahamian, R.; Evensen, D. A.

    1971-01-01

    Method photographs vibration modes as high as 100 kHz. Technique also measures vibration decay and damping characteristics. Compensation techniques for structural size limitations and for background noise excitations are discussed.

  7. Soil chemical insights provided through vibrational spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vibrational spectroscopy techniques provide a powerful approach to study environmental materials and processes. These multifunctional analysis tools can be used to probe molecular vibrations of solid, liquid, and gaseous samples for characterizing materials, elucidating reaction mechanisms, and exam...

  8. Vibration dampers for cryogenic turbomachinery

    NASA Technical Reports Server (NTRS)

    Palazzolo, Alan B.; Olan, Emmanuel; Ibrahim, Azman Syed; Kascak, Albert F.

    1990-01-01

    This paper describes the development of effective and reliable minimum-weight and minimum-envelope vibration dampers for cryogenic turbines. To meet this objective, a high speed test rig was designed and fabricated, which is currently used to test a curved beam type damper. The operation, capacity, structural characteristics, measurement system, and safety features of the cryogenic damper test rig are discussed.

  9. Vibration analysis utilizing Mossbauer effect

    NASA Technical Reports Server (NTRS)

    Roughton, N. A.

    1967-01-01

    Measuring instrument analyzes mechanical vibrations in transducers at amplitudes in the range of a few to 100 angstroms. This instrument utilizes the Mossbauer effect, the phenomenon of the recoil-free emission and resonant absorption of nuclear gamma rays in solids.

  10. "Three-dimensional" vibration fixture

    NASA Technical Reports Server (NTRS)

    Schumacher, C. A.

    1980-01-01

    Simple cube-shaped fixture reduces vibration-test time to one-third required previously. Three units are supported at once. During one run each unit is tested along one of axes. Units are repositioned on second run for tests along different axes. Three runs complete test; fixture can be set up to test small, lightweight high-production units.

  11. Vibrating-chamber levitation systems

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Granett, D.; Lee, M. C. (Inventor)

    1985-01-01

    Systems are described for the acoustic levitation of objects, which enable the use of a sealed rigid chamber to avoid contamination of the levitated object. The apparatus includes a housing forming a substantially closed chamber, and means for vibrating the entire housing at a frequency that produces an acoustic standing wave pattern within the chamber.

  12. Hydrogen rotation-vibration oscillator

    DOEpatents

    Rhodes, C.K.

    1974-01-29

    A laser system is described wherein molecular species of hydrogen and hydrogen isotopes are induced to oscillate on rotational-vibrational levels by subjecting the hydrogen to a transverse beam of electrons of a narrowly defined energy between about 1 and 5 eV, thereby producing high intensity and high energy output. (Official Gazette)

  13. Vibrating-chamber levitation systems

    NASA Astrophysics Data System (ADS)

    Barmatz, M. B.; Granett, D.; Lee, M. C.

    1985-10-01

    Systems are described for the acoustic levitation of objects, which enable the use of a sealed rigid chamber to avoid contamination of the levitated object. The apparatus includes a housing forming a substantially closed chamber, and means for vibrating the entire housing at a frequency that produces an acoustic standing wave pattern within the chamber.

  14. Vibrational soliton: an experimental overview

    SciTech Connect

    Bigio, I.J.

    1986-03-08

    To date the most convincing evidence of vibrational solitons in biopolymers has been found in two very disparate systems: Davydov-like excitations in hydrogen-bonded linear chains (acetanilide and N-methylacetamide) which are not biopolymers but plausible structural paradigms for biopolymers, and longitudinal accoustic modes of possibly nonlinear character in biologically viable DNA. 17 refs., 4 figs.

  15. Spectral compressor vibration analysis techniques

    SciTech Connect

    Hanson, M.L.

    1982-02-01

    Studies at GAT have verified that the spectral distribution of energy in gaseous diffusion compressor vibrations contains information pertinent to the state of the compressor's ''health.'' Based on that conclusion, vibration analysis capabilities were included in the CUP computer data acquisition system. In order for that information to be used for diagnosis of incipient failure mechanisms, however, spectral features must be empirically associated with actual malfunctions and validated statistically as diagnostic symptoms. When the system was acquired, indicators were generally unknown except for those associated with unbalance, misalignment, 00 secondary surge and severe resonant blade vibrations. Others must be developed as in-service malfunctions occur. The power spectral density function (PSDF) has historically been used to compute vibration spectra. Accurate, high-resolution power density spectra require long data-acquisition periods which is inconsistent with frequent examinations of all up-rated compressors. Detection of gross spectral changes indicative of a need for detailed analyses has been accomplished at a rate of less than 1 minute per compressor. An optimum analytical sequence will be based on trade offs. Work is in progress to identify additional malfunction indicators and investigate tools other than the PSDF to provide faster diagnoses. 6 figs.

  16. The broadband dynamic vibration absorber

    NASA Astrophysics Data System (ADS)

    Hunt, J. B.; Nissen, J.-C.

    1982-08-01

    The limited effectiveness of the linear passive dynamic vibration absorber is described. This is followed by an analysis producing the response of a primary system when a non-linear softening Belleville spring is used in the absorber. It is shown that the suppression bandwidth can be doubled by this means.

  17. Quantification of mouse in vivo whole-body vibration amplitude from motion-blur using x-ray imaging.

    PubMed

    Hu, Zhengyi; Welch, Ian; Yuan, Xunhua; Pollmann, Steven I; Nikolov, Hristo N; Holdsworth, David W

    2015-08-21

    Musculoskeletal effects of whole-body vibration on animals and humans have become an intensely studied topic recently, due to the potential of applying this method as a non-pharmacological therapy for strengthening bones. It is relatively easy to quantify the transmission of whole-body mechanical vibration through the human skeletal system using accelerometers. However, this is not the case for small-animal pre-clinical studies because currently available accelerometers have a large mass, relative to the mass of the animals, which causes the accelerometers themselves to affect the way vibration is transmitted. Additionally, live animals do not typically remain motionless for long periods, unless they are anesthetized, and they are required to maintain a static standing posture during these studies. These challenges provide the motivation for the development of a method to quantify vibrational transmission in small animals. We present a novel imaging technique to quantify whole-body vibration transmission in small animals using 280 μm diameter tungsten carbide beads implanted into the hind limbs of mice. Employing time-exposure digital x-ray imaging, vibrational amplitude is quantified based on the blurring of the implanted beads caused by the vibrational motion. Our in vivo results have shown this technique is capable of measuring vibration amplitudes as small as 0.1 mm, with precision as small as  ±10 μm, allowing us to distinguish differences in the transmitted vibration at different locations on the hindlimbs of mice.

  18. Enhanced-resolution image restoration from a sequence of low-frequency vibrated images by use of convex projections.

    PubMed

    Stern, A; Porat, Y; Ben-Dor, A; Kopeika, N S

    2001-09-10

    An algorithm to increase the spatial resolution of digital video sequences captured with a camera that is subject to mechanical vibration is developed. The blur caused by vibration of the camera is often the primary cause for image degradation. We address the degradation caused by low-frequency vibrations (vibrations for which the exposure time is less than the vibration period). The blur caused by low-frequency vibrations differs from other types by having a random shape and displacement. The different displacement of each frame makes the approach used in superresolution (SR) algorithms suitable for resolution enhancement. However, SR algorithms that were developed for general types of blur should be adapted to the specific characteristics of low-frequency vibration blur. We use the method of projection onto convex sets together with a motion estimation method specially adapted to low-frequency vibration blur characteristics. We also show that the random blur characterizing low-frequency vibration requires selection of the frames prior to processing. The restoration performance as well as the frame selection criteria is dependent mainly on the motion estimation precision.

  19. Quantification of mouse in vivo whole-body vibration amplitude from motion-blur using x-ray imaging.

    PubMed

    Hu, Zhengyi; Welch, Ian; Yuan, Xunhua; Pollmann, Steven I; Nikolov, Hristo N; Holdsworth, David W

    2015-08-21

    Musculoskeletal effects of whole-body vibration on animals and humans have become an intensely studied topic recently, due to the potential of applying this method as a non-pharmacological therapy for strengthening bones. It is relatively easy to quantify the transmission of whole-body mechanical vibration through the human skeletal system using accelerometers. However, this is not the case for small-animal pre-clinical studies because currently available accelerometers have a large mass, relative to the mass of the animals, which causes the accelerometers themselves to affect the way vibration is transmitted. Additionally, live animals do not typically remain motionless for long periods, unless they are anesthetized, and they are required to maintain a static standing posture during these studies. These challenges provide the motivation for the development of a method to quantify vibrational transmission in small animals. We present a novel imaging technique to quantify whole-body vibration transmission in small animals using 280 μm diameter tungsten carbide beads implanted into the hind limbs of mice. Employing time-exposure digital x-ray imaging, vibrational amplitude is quantified based on the blurring of the implanted beads caused by the vibrational motion. Our in vivo results have shown this technique is capable of measuring vibration amplitudes as small as 0.1 mm, with precision as small as  ±10 μm, allowing us to distinguish differences in the transmitted vibration at different locations on the hindlimbs of mice. PMID:26248045

  20. Quantification of mouse in vivo whole-body vibration amplitude from motion-blur using x-ray imaging

    NASA Astrophysics Data System (ADS)

    Hu, Zhengyi; Welch, Ian; Yuan, Xunhua; Pollmann, Steven I.; Nikolov, Hristo N.; Holdsworth, David W.

    2015-08-01

    Musculoskeletal effects of whole-body vibration on animals and humans have become an intensely studied topic recently, due to the potential of applying this method as a non-pharmacological therapy for strengthening bones. It is relatively easy to quantify the transmission of whole-body mechanical vibration through the human skeletal system using accelerometers. However, this is not the case for small-animal pre-clinical studies because currently available accelerometers have a large mass, relative to the mass of the animals, which causes the accelerometers themselves to affect the way vibration is transmitted. Additionally, live animals do not typically remain motionless for long periods, unless they are anesthetized, and they are required to maintain a static standing posture during these studies. These challenges provide the motivation for the development of a method to quantify vibrational transmission in small animals. We present a novel imaging technique to quantify whole-body vibration transmission in small animals using 280 μm diameter tungsten carbide beads implanted into the hind limbs of mice. Employing time-exposure digital x-ray imaging, vibrational amplitude is quantified based on the blurring of the implanted beads caused by the vibrational motion. Our in vivo results have shown this technique is capable of measuring vibration amplitudes as small as 0.1 mm, with precision as small as  ±10 μm, allowing us to distinguish differences in the transmitted vibration at different locations on the hindlimbs of mice.

  1. Whole-body vibration and disorders of the spine.

    PubMed

    Dupuis, H; Zerlett, G

    1987-01-01

    This cross-sectional study is based on interviews and medical examinations of 352 operators of earth-moving machines who had been exposed to whole-body vibrations for at least three years. In addition, available X-rays showing different parts of the spines of 251 machine operators who had been exposed to vibration for at least ten years were used for evaluation. One hundred and forty-nine of the operators were asked about discomfort occurring immediately after an eight-hour work shift. The group of exposed persons was compared with a control group of 215 non-exposed persons. The percentage of subjects reporting spinal discomfort was much higher for the exposed group than for the non-exposed group. 68.7% of the operators complained of spinal discomfort in the lumbar spine, 6.8% in the thoracic column and 18.2% in the cervical column. The discomfort reported immediately after an eight-hour exposure to whole-body vibration was highly age-dependent. The epidemiological study resulted in an objective conformation of the spinal discomfort reported, 2/3 of which were related by the operators to the lumbar syndrome. Lumbar syndrome (81%) accounted for by far the highest number of spinal disorders. Examinations of the operators with at least ten years of exposure to whole-body vibrations showed that morphological changes in the lumbar spine occur earlier and much more frequently than in the case of non-exposed persons. Problems of etiology and pathogenesis are discussed.

  2. Vibrating Beam With Spatially Periodic Stiffness

    NASA Technical Reports Server (NTRS)

    Townsend, John S.

    1989-01-01

    Report presents theoretical analysis of vibrations of simply supported beam, bending stiffness varying about steady value, sinusoidally with position along length. Problem of practical importance because related to vibrations of twisted-pair electric-power transmission lines. Twists promote nonuniform shedding of vortexes and prevents resonant accumulation of vibrational energy from wind.

  3. 21 CFR 890.5975 - Therapeutic vibrator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Therapeutic vibrator. 890.5975 Section 890.5975...) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5975 Therapeutic vibrator. (a) Identification. A therapeutic vibrator is an electrically powered device intended for...

  4. 14 CFR 27.251 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  5. 49 CFR 178.608 - Vibration standard.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Vibration standard. 178.608 Section 178.608... Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section. (b) Test method....

  6. 14 CFR 29.907 - Engine vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b)...

  7. 14 CFR 29.907 - Engine vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b)...

  8. 14 CFR 27.251 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  9. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine vibration. 27.907 Section 27.907... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant General § 27.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The addition of...

  10. 14 CFR 29.251 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  11. 49 CFR 178.985 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Vibration test. 178.985 Section 178.985... Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A sample...

  12. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine vibration. 27.907 Section 27.907... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant General § 27.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The addition of...

  13. 49 CFR 178.985 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.985 Section 178.985... Testing of Large Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1)...

  14. 14 CFR 29.907 - Engine vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b)...

  15. 14 CFR 29.907 - Engine vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b)...

  16. 14 CFR 29.251 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  17. 49 CFR 178.985 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Vibration test. 178.985 Section 178.985... Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A sample...

  18. 14 CFR 27.251 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  19. 14 CFR 29.251 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  20. 14 CFR 29.251 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  1. 49 CFR 178.608 - Vibration standard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Vibration standard. 178.608 Section 178.608... Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section. (b) Test method....

  2. 33 CFR 159.103 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vibration test. 159.103 Section...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The device... subjected to a sinusoidal vibration for a period of 12 hours, 4 hours in each of the x, y, and z planes,...

  3. 49 CFR 178.985 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Vibration test. 178.985 Section 178.985... Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A sample...

  4. 33 CFR 159.103 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Vibration test. 159.103 Section...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The device... subjected to a sinusoidal vibration for a period of 12 hours, 4 hours in each of the x, y, and z planes,...

  5. 14 CFR 27.251 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  6. 14 CFR 29.251 - Vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  7. 14 CFR 27.251 - Vibration.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and...

  8. 49 CFR 178.608 - Vibration standard.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration standard. 178.608 Section 178.608... Testing of Non-bulk Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this...

  9. Ground Vibration Measurements at LHC Point 4

    SciTech Connect

    Bertsche, Kirk; Gaddi, Andrea; /CERN

    2012-09-17

    Ground vibration was measured at Large Hadron Collider (LHC) Point 4 during the winter shutdown in February 2012. This report contains the results, including power and coherence spectra. We plan to collect and analyze vibration data from representative collider halls to inform specifications for future linear colliders, such as ILC and CLIC. We are especially interested in vibration correlations between final focus lens locations.

  10. 14 CFR 29.907 - Engine vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b)...

  11. 33 CFR 159.103 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Vibration test. 159.103 Section...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The device... subjected to a sinusoidal vibration for a period of 12 hours, 4 hours in each of the x, y, and z planes,...

  12. 49 CFR 178.608 - Vibration standard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Vibration standard. 178.608 Section 178.608... Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section. (b) Test method....

  13. 49 CFR 178.608 - Vibration standard.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Vibration standard. 178.608 Section 178.608... Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section. (b) Test method....

  14. 49 CFR 178.985 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Vibration test. 178.985 Section 178.985... Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A sample...

  15. Actively Controlled Magnetic Vibration-Isolation System

    NASA Technical Reports Server (NTRS)

    Grodsinky, Carlos M.; Logsdon, Kirk A.; Wbomski, Joseph F.; Brown, Gerald V.

    1993-01-01

    Prototype magnetic suspension system with active control isolates object from vibrations in all six degrees of freedom at frequencies as low as 0.01 Hz. Designed specifically to protect instruments aboard spacecraft by suppressing vibrations to microgravity levels; basic control approach used for such terrestrial uses as suppression of shocks and other vibrations in trucks and railroad cars.

  16. Worker awareness of exposure: industries and occupations with low awareness.

    PubMed

    Behrens, V J; Brackbill, R M

    1993-05-01

    A goal of occupational health is to inform workers of hazards on their jobs. This analysis addresses this goal by identifying industries and occupations with low worker awareness of potential exposures. Industries and occupations were ranked by the greatest positive difference between the proportion of workers exposed and proportion perceiving exposure to chemical and physical hazards. Those with low awareness had the greatest difference, i.e., high exposure and low perception. This analysis was performed by adding exposure data from a national exposure survey to a national health survey with perceived exposure data. The hospital and construction industries and occupations in these industries ranked among the top five for all hazards. For example, for hospital workers the difference between proportion exposed and proportion perceiving exposure to chemicals was 62% and to radiation was 42%, and for workers in construction the difference was 54% for exposure to noise and 63% for exposure to vibration.

  17. Method for enriching a middle isotope using vibration-vibration pumping

    DOEpatents

    Rich, Joseph W.; Homicz, Gregory F.; Bergman, Richard C.

    1989-01-01

    Method for producing isotopically enriched material by vibration-vibration excitation of gaseous molecules wherein a middle mass isotope of an isotopic mixture including lighter and heavier mass isotopes preferentially populates a higher vibrational mode and chemically reacts to provide a product in which it is enriched. The method can be used for vibration-vibration enrichment of .sup.17 O in a CO reactant mixture.

  18. Variational study on the vibrational level structure and vibrational level mixing of highly vibrationally excited S₀ D₂CO.

    PubMed

    Rashev, Svetoslav; Moule, David C; Rashev, Vladimir

    2012-11-01

    We perform converged high precision variational calculations to determine the frequencies of a large number of vibrational levels in S(0) D(2)CO, extending from low to very high excess vibrational energies. For the calculations we use our specific vibrational method (recently employed for studies on H(2)CO), consisting of a combination of a search/selection algorithm and a Lanczos iteration procedure. Using the same method we perform large scale converged calculations on the vibrational level spectral structure and fragmentation at selected highly excited overtone states, up to excess vibrational energies of ∼17,000 cm(-1), in order to study the characteristics of intramolecular vibrational redistribution (IVR), vibrational level density and mode selectivity. PMID:22750345

  19. Whole-body vibration perception thresholds

    NASA Astrophysics Data System (ADS)

    Parsons, K. C.; Griffin, M. J.

    1988-03-01

    This paper presents the results of a series of laboratory experiments concerned with perception thresholds for whole-body vibration. The nature of absolute perception thresholds is discussed and a method of determining vibration thresholds, based upon signal detection theory, is proposed. Thresholds of subjects exposed to x-, y- and z-axis sinusoidal vibration were determined for sitting and standing subjects (from 2 to 100 Hz). Perception thresholds have also been determined for supine subjects exposed to vertical ( x-axis) sinusoidal vibration (10-63 Hz). In additional experiments the effects of complex (e.g., random) vibration and the effects of duration on the perception thresholds were investigated. The relation between perception thresholds and vibration levels, said by subjects to be unacceptable if they occurred in their own homes, was investigated as well as the effects of subjects' personality and the visual and acoustic conditions in the laboratory. For the vertical vibration of seated subjects no significant differences were found between the responses of male and female subjects. Significant differences were found between perception thresholds for sitting and standing postures. The median threshold was approximately 0·01 m/s 2 r.m.s. between 2 and 100 Hz. Perception thresholds for x-axis and y-axis vibration were not significantly different in either sitting or standing subjects but significant differences in thresholds were found between sitting and standing positions for both x-axis and y-axis vibration. Subjects tended to be more sensitive to vibration when lying than when sitting or standing. The results suggested that the perception of random vibrations can be predicted from a knowledge of the perception of its component vibrations. The number of cycles of vibration did not affect perception thresholds for vibration durations of more than about 0·25 s. Some assessments suggested that vibration at more than twice the perception threshold may not

  20. The effects of sound level and vibration magnitude on the relative discomfort of noise and vibration.

    PubMed

    Huang, Yu; Griffin, Michael J

    2012-06-01

    The relative discomfort caused by noise and vibration, how this depends on the level of noise and the magnitude of vibration, and whether the noise and vibration are presented simultaneously or sequentially has been investigated in a laboratory study with 20 subjects. Noise and vertical vibration were reproduced with all 49 combinations of 7 levels of noise and 7 magnitudes of vibration to allow the discomfort caused by one of the stimuli to be judged relative to the other stimulus using magnitude estimation. In four sessions, subjects judged noise relative to vibration and vibration relative to noise, with both simultaneous and sequential presentations of the stimuli. The equivalence of noise and vibration was not greatly dependent on whether the stimuli were simultaneous or sequential, but highly dependent on whether noise was judged relative to vibration or vibration was judged relative to noise. When judging noise, higher magnitude vibrations appeared to mask the discomfort caused by low levels of noise. When judging vibration, higher level noises appeared to mask the discomfort caused by low magnitudes of vibration. The judgment of vibration discomfort was more influenced by noise than the judgment of noise discomfort was influenced by vibration.

  1. Active Suppression Of Vibrations On Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    1995-01-01

    Method of active suppression of nonlinear and nonstationary vibrations developed to reduce sonic fatigue and interior noise in high-speed aircraft. Structure of aircraft exhibits periodic, chaotic, and random vibrations when forced by high-intensity sound from jet engines, shock waves, turbulence, and separated flows. Method of suppressing vibrations involves feedback control: Strain gauges or other sensors mounted in paths of propagation of vibrations on structure sense vibrations; outputs of sensors processed into control signal applied to actuator mounted on structure, inducing compensatory forces.

  2. Interfacial instabilities in vibrated fluids

    NASA Astrophysics Data System (ADS)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  3. Multiple Rabi Splittings under Ultrastrong Vibrational Coupling

    NASA Astrophysics Data System (ADS)

    George, Jino; Chervy, Thibault; Shalabney, Atef; Devaux, Eloïse; Hiura, Hidefumi; Genet, Cyriaque; Ebbesen, Thomas W.

    2016-10-01

    From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultrastrongly coupled to multiple IR cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. As a proof of the ultrastrong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the antiresonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic band gap of ca. 60 meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultrastrong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular, in the context of mode-selective chemistry.

  4. Probing zeolites by vibrational spectroscopies.

    PubMed

    Bordiga, Silvia; Lamberti, Carlo; Bonino, Francesca; Travert, Arnaud; Thibault-Starzyk, Frédéric

    2015-10-21

    This review addresses the most relevant aspects of vibrational spectroscopies (IR, Raman and INS) applied to zeolites and zeotype materials. Surface Brønsted and Lewis acidity and surface basicity are treated in detail. The role of probe molecules and the relevance of tuning both the proton affinity and the steric hindrance of the probe to fully understand and map the complex site population present inside microporous materials are critically discussed. A detailed description of the methods needed to precisely determine the IR absorption coefficients is given, making IR a quantitative technique. The thermodynamic parameters of the adsorption process that can be extracted from a variable-temperature IR study are described. Finally, cutting-edge space- and time-resolved experiments are reviewed. All aspects are discussed by reporting relevant examples. When available, the theoretical literature related to the reviewed experimental results is reported to support the interpretation of the vibrational spectra on an atomic level.

  5. VIBRATION DAMPING AND SHOCK MOUNT

    DOEpatents

    Stevens, D.J.; Forman, G.W.

    1963-12-10

    A shock absorbing mount in which vibrations are damped by an interference fit between relatively movable parts of the mount is described. A pair of generally cup-shaped parts or members have skirt portions disposed in an oppositely facing nesting relationship with the skirt of one member frictionally engaging the skirt of the other. The outermost skirt may be slotted to provide spring-like segments which embrace the inner skirt for effecting the interference fit. Belleville washers between the members provide yieldable support for a load carried by the mount. When a resonant frequency of vibration forces acting upon the moumt attains a certain level the kinetic energy of these forces is absorbed by sliding friction between the parts. (AEC)

  6. Torsional vibration isolator and method

    SciTech Connect

    Allen, C.A.; Durrett, V.D.

    1986-10-21

    This patent describes a multicylinder internal combustion engine having a rotatable crankshaft and a rotatable flywheel which together define an inertial system rotating about a predetermined axis of rotation. An improvement is described here which facilitates avoiding destructive effects on the crankshaft of stress induced by torsional vibration. The method comprises an elastomeric annulus coupling means operatively interposed between the crankshaft and flywheel for coupling the crankshaft and flywheel together for rotation of the flywheel with the crankshaft. The coupling means has a torsional spring rate of less than 20,000 in lb/radian effective to permit substantial angular displacement between the flywheel and the crankshaft for isolating the rotating inertia of the flywheel from the rotating inertia of the crankshaft after engine startup. The coupling means avoids dampening while preventing torsional vibration from being transferred between the flywheel and the crankshaft.

  7. Vibrational energy transfer in fluids

    NASA Astrophysics Data System (ADS)

    Miller, David W.; Adelman, Steven A.

    A review of several of the available theories of vibrational energy transfer (VET) in the gas and liquid phases is presented. First the classical theory of gas phase VET mainly due to Landau and Teller, to Jackson and Mott and to Zener is developed in some detail. Next the Schwartz-Slawsky-Herzfeld theory, a framework for analysing VET data based on the classical theory, is outlined. Experimental tests of the classical theory and theoretical critiques of its assumptions are then described. Next a brief review of the modern ab-initio quantum approach to gas phase VET rates, taking as an example the work of Banks, Clary and Werner, is given. Theories of VET at elevated densities are then discussed. The isolated binary collision model is reviewed and a new molecular approach to the density, temperature and isotope dependences of vibrational energy relaxation rates, due to Adelman and co-workers, is outlined.

  8. Vibrational damping of composite materials

    NASA Astrophysics Data System (ADS)

    Biggerstaff, Janet M.

    The purpose of this research was to develop new methods of vibrational damping in polymeric composite materials along with expanding the knowledge of currently used vibrational damping methods. A new barrier layer technique that dramatically increased damping in viscoelastic damping materials that interacted with the composite resin was created. A method for testing the shear strength of damping materials cocured in composites was developed. Directional damping materials, where the loss factor and modulus could be tailored by changing the angle, were produced and investigated. The addition of particles between composite prepreg layers to increase damping was studied. Electroviscoelastic materials that drastically changed properties such as loss factor and modulus with an applied voltage were manufactured and tested.

  9. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-01-09

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program entails modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. The project continues to advance, but is behind the revised (14-month) schedule. Tasks 1-3 (Modeling, Specification and Design) are all essentially complete. The test bench for the Test and Evaluation (Tasks 4 & 5) has been designed and constructed. The design of the full-scale laboratory prototype and associated test equipment is complete and the components are out for manufacture. Barring any unforeseen difficulties, laboratory testing should be complete by the end of March, as currently scheduled. We anticipate the expenses through March to be approximately equal to those budgeted for Phase I.

  10. Magnetic bearings for vibration control

    NASA Technical Reports Server (NTRS)

    Schweitzer, G.

    1985-01-01

    A survey is presented on the research of the Institute of Mechanics of the ETH in the field of vibration control with magnetic bearings. It shows a method for modelling an elastic rotor so that it can be represented by a low order model amenable to control techniques. It deals with the control law and spill-over effects, and it also discusses experimental results for an active resonance damper.

  11. Vibrational excitation induces double reaction.

    PubMed

    Huang, Kai; Leung, Lydie; Lim, Tingbin; Ning, Zhanyu; Polanyi, John C

    2014-12-23

    Electron-induced reaction at metal surfaces is currently the subject of extensive study. Here, we broaden the range of experimentation to a comparison of vibrational excitation with electronic excitation, for reaction of the same molecule at the same clean metal surface. In a previous study of electron-induced reaction by scanning tunneling microscopy (STM), we examined the dynamics of the concurrent breaking of the two C-I bonds of ortho-diiodobenzene physisorbed on Cu(110). The energy of the incident electron was near the electronic excitation threshold of E0=1.0 eV required to induce this single-electron process. STM has been employed in the present work to study the reaction dynamics at the substantially lower incident electron energies of 0.3 eV, well below the electronic excitation threshold. The observed increase in reaction rate with current was found to be fourth-order, indicative of multistep reagent vibrational excitation, in contrast to the first-order rate dependence found earlier for electronic excitation. The change in mode of excitation was accompanied by altered reaction dynamics, evidenced by a different pattern of binding of the chemisorbed products to the copper surface. We have modeled these altered reaction dynamics by exciting normal modes of vibration that distort the C-I bonds of the physisorbed reagent. Using the same ab initio ground potential-energy surface as in the prior work on electronic excitation, but with only vibrational excitation of the physisorbed reagent in the asymmetric stretch mode of C-I bonds, we obtained the observed alteration in reaction dynamics.

  12. Vibrational assignments of 2-iodopyridine

    NASA Astrophysics Data System (ADS)

    Sortur, Veenasangeeta; Yenagi, Jayashree; Tonannavar, J.

    2008-02-01

    A review of the vibrational assignments for 2-iodopyridine has been proposed based on the FT-Raman (3500-50 cm -1) and IR (4000-400 cm -1) spectral measurements. Equilibrium geometries and vibrational frequencies have been computed from a variety of electronic structure methods: the ab initio (RHF), six DFT (BLYP, BP86, B3LYP, B3P86, B3PW91 and SVWN) and MP2 methods using 3-21G*, LANL2DZ and DGDZVP basis sets. A normal coordinate analysis has been carried out: the normal modes and their couplings are characterized in terms of potential energy distributions (PEDs). The comparison of assignments for pyridine and halopyridines shows that several of the normal modes arise from coupled vibrations in 2-iodopyridine. The BP86 and B3LYP methods with LANL2DZ basis set have performed reasonably well in reproducing the observed spectra, demonstrating that the LANL2DZ basis set (with effective core potential representations of electrons near the nuclei for post-third row atoms) is suitable for 2-iodopyridine.

  13. Resonance vibrations of buried landmines

    NASA Astrophysics Data System (ADS)

    Zagrai, Andrei N.; Donskoy, Dimitri M.; Ekimov, Alexander E.

    2004-09-01

    Resonance behavior of many types of landmines was first experimentally discovered in 2000 (Donskoy et al. in Proceedings of SPIE Vol. 4394, pp. 575-582, 2001). Laboratory studies and field tests have shown that mine"s resonance response is a complex phenomenon dependent upon interaction between soil and mines and their respective properties. Although the resonance effect was successfully used by various research teams for detection of landmines, there were no thorough studies on various factors influencing buried mine's resonance response. This paper presents results of theoretical and experimental investigation of this problem including multi-modal structure of mine's vibration response, effect of burial depth and soil condition. In the modeling efforts we considered multiple modes of vibration of mine casing and represented them as oscillators with effective parameters. This approach allowed for simplification of analysis and expanding existing lump-element model to account for multiple vibration modes. The experimental tests were focused on studying the effects of burial depth and soil moisture content on resonance behavior of soil-mine system. The tests have shown that a resonance frequency initially decreases with burial depth, as expected. However, an anomalous resonance frequency increase was observed at greater depths; soil moisture even further increases the resonance frequency.

  14. Reduced-vibration tube array

    DOEpatents

    Bruck, Gerald J.; Bartolomeo, Daniel R.

    2004-07-20

    A reduced-vibration tube array is disclosed. The array includes a plurality of tubes in a fixed arrangement and a plurality of damping members positioned within the tubes. The damping members include contoured interface regions characterized by bracing points that selectively contact the inner surface of an associated tube. Each interface region is sized and shaped in accordance with the associated tube, so that the damping member bracing points are spaced apart a vibration-reducing distance from the associated tube inner surfaces at equilibrium. During operation, mechanical interaction between the bracing points and the tube inner surfaces reduces vibration by a damage-reducing degree. In one embodiment, the interface regions are serpentine shaped. In another embodiment, the interface regions are helical in shape. The interface regions may be simultaneously helical and serpentine in shape. The damping members may be fixed within the associated tubes, and damping member may be customized several interference regions having attributes chosen in accordance with desired flow characteristics and associated tube properties.

  15. Vibrational and theoretical study of diacetylenic acids.

    PubMed

    Roman, Maciej; Baranska, Malgorzata

    2015-02-25

    Three selected diacetylenic acids (DAs) with side-chains of various length (CH3-(CH2)m-C≡C-C≡C(CH2)n-COOH, where m=7, 9, 11, and n=3, 8) were analyzed using vibrational spectroscopy and quantum-chemical calculations. The conformational analysis was followed by potential energy distribution (PED) calculations to gain deeper insight into their FT-Raman and FT-IR spectra. The analysis was focused on spectral features of the diacetylene system sensitive to the substitution. In particular, the electron donor-acceptor properties of the substituent and the influence of side-chain length were studied. FT-IR spectra were measured by using two techniques, i.e. transmission (with KBr substrate) and Attenuated Total Reflection (ATR), and the latter seems to be less adequate for DAs measurements because the bands in the fingerprint region as well as the ν(C≡C)as mode are relatively of low intensity. Additionally, polymerization process of DAs was recognized using FT-Raman spectroscopy and strong and well-separated bands of diacetylenic polymers. Temperature and exposure to the sunlight are the factors of an important influence on the polymerization process of DAs. Since the investigated DAs are carboxylic acids, the interpretation of experimental spectra was performed on the basis of monomer and dimer calculations.

  16. Whole body vibration and posture as risk factors for low back pain among forklift truck drivers

    NASA Astrophysics Data System (ADS)

    Hoy, J.; Mubarak, N.; Nelson, S.; Sweerts de Landas, M.; Magnusson, M.; Okunribido, O.; Pope, M.

    2005-06-01

    A cross-sectional study was conducted to investigate the risks from whole-body vibration and posture demands for low back pain (LBP) among forklift truck (forklift) drivers. Using a validated questionnaire, information about health history was obtained over a period of two weeks in face-to-face interviews. The forklift drivers were observed in respect of their sitting posture, including frequency with which different positions were adopted (bending, leaning and twisting) and postural analyses were conducted using the OWAS and RULA techniques. Forklift vibrations at the seat (exposure) were measured in the three orthogonal axes ( x-fore and aft, y-lateral and z-vertical) under actual working conditions according to the recommendations of ISO 2631-1. The results showed that LBP was more prevalent amongst forklift drivers than among non-drivers and driving postures in which the trunk is considerably twisted or bent forward associated with greatest risk. Furthermore, forklift drivers showed to be exposed to acceptable levels of vibration in the x- and y-directions (i.e., below the EU Physical Agents Directive on Vibration Exposure recommended action level—0.5 m/s 2), but not in the z-direction. There were indications that whole-body vibration acts associatively with other factors (not independently) to precipitate LBP.

  17. Low back pain in drivers: The relative role of whole-body vibration, posture and manual materials handling

    NASA Astrophysics Data System (ADS)

    Okunribido, O. O.; Magnusson, M.; Pope, M. H.

    2006-12-01

    A cross-sectional study was conducted to investigate the relative role of whole-body vibration (WBV), posture and manual materials handling (MMH) as risk factors for low back pain (LBP). Using a validated questionnaire, information about health history, posture and MMH performed was obtained from 394 workers who drove vehicles as part of their job (according to seven predefined occupational groups) and 59 who did not. The intention was to reflect a wide range of exposures with the lower end of the exposure spectrum defined as that of non-manual workers who do not drive as part of their job. Based on the questionnaire responses and direct measurements of vibration exposure, personal aggregate measures of exposure were computed for each of the respondents, i.e., total vibration dose (TVD), posture score (PS) and manual handling score (MHS). Odds ratios (and 95% confidence intervals) for back pain were obtained from logistics regression models and log-linear backward elimination analysis was performed. The findings showed that 'combined exposure' due to posture and one or both of vibration and MMH, rather than the individual exposure to one of the three factors (WBV, posture, MMH) is the main contributor of the increased prevalence of LBP.

  18. Characteristics of large capacity ultrasonic complex vibration sources with stepped complex transverse vibration rods.

    PubMed

    Tsujino, J; Ueoka, T

    2004-04-01

    Configurations of large capacity ultrasonic complex vibration sources with multiple longitudinal transducers are proposed and studied. The ultrasonic complex vibration systems are effective and essential for new applications in various industries. The complex vibration source of 27 kHz consists of a complex transverse rod with a welding tip (aluminum alloy, stainless steel and titanium alloy), a complex vibration rod with a flange and stepped part for holding the system, a circular longitudinal vibration disk (aluminum alloy) and six bolt-clamped Langevin type PLT transducers. Three transducer pairs are driven simultaneously using three driving systems at phase difference 120 degrees, and almost circular vibration locus is obtained.

  19. Ground test for vibration control demonstrator

    NASA Astrophysics Data System (ADS)

    Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

    2016-09-01

    In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

  20. EXPOSURE ANALYSIS

    EPA Science Inventory

    This proceedings chapter will discuss the state-of-the-science regarding the evaluation of exposure as it relates to water quality criteria (WQC), sediment quality guidelines (SQG), and wildlife criteria (WC). Throughout this discussion, attempts are made to identify the methods ...

  1. Hypotonic exposures.

    PubMed

    Flynn, W J; Hill, R M

    1984-03-01

    Even without a contact lens, the cornea can suffer adverse physiological changes from hypotonic exposure, as well as the associated subjective phenomena (e.g., halo and rainbows). The contact lens adds a dimension to this problem that should be viewed against a background of normal (non-wearing) susceptibilities. PMID:6715776

  2. State-to-state vibration-translation and vibration-vibration rate constants in H{sub 2}-H{sub 2} and HD-HD collisions

    SciTech Connect

    Cacciatore, M.; Billing G.D.

    1992-01-09

    The authors present calculations of vibration-vibration and vibration-translation energy transfer rate constants in diatom-diatom collisions. The results are compared to recent experimental measurements.

  3. Smart Structures for Vibration Control on Long-Term Space Exploration and Habitation Missions

    NASA Technical Reports Server (NTRS)

    Gattis, Christy B.; Shepard, W. Steve, Jr.

    2004-01-01

    The current vision for space exploration focuses on human missions to the Moon, Mars, and beyond. To support these goals, it is certain that new vehicles and intermediate bases will be developed, whether that means simply re-direction of the ISS as a "mission research facility" or construction of a lunar base. Since these facilities are expected to be constructed from inherently light-weight materials, this work examines some of the potential sources of vibration and noise as well as means for controlling these vibrations. Many of the operating components within these facilities, such as pumps, fans, and motors, will produce vibrations during operation. These vibrations become structure in which they are housed. Resonances can impact acoustic noise levels and noise quality within the environment, possibly affecting crew health and productivity. For long-term missions in particular, it is expected that crew members will spend significant portions of their time restrained in the structure, such as in seats. As a result, the general health and well-being of the crew can be improved by limiting the harmful effects of human exposure to long-term audible and tactile vibration input. Besides the human factor, this work also examines some operational considerations in which vibrations play an important role. Vibrations can impact the environment for science and in-situ manufacturing research within these vehicles. Since a benign vibratory environment is beneficial for most types of science experiments, there is a need for various forms of vibration control. Because the operational characteristics of a vehicle can change during a long-term mission, it is further expected that the characteristics of many of the vibratory excitations will change with time. Consequently, the form of vibration control needed to improve overall habitability and usefulness of the vehicle or element for exploration missions will rely to some degree on the vibration control system's ability to

  4. The effects of repetitive vibration on sensorineural function: biomarkers of sensorineural injury in an animal model of metabolic syndrome

    PubMed Central

    Kiedrowski, Megan; Waugh, Stacey; Miller, Roger; Johnson, Claud; Krajnak, Kristine

    2016-01-01

    Exposure to hand-transmitted vibration in the work-place can result in the loss of sensation and pain in workers. These effects may be exacerbated by pre-existing conditions such as diabetes or the presence of primary Raynaud's phenomena. The goal of these studies was to use an established model of vibration-induced injury in Zucker rats. Lean Zucker rats have a normal metabolic profile, while obese Zucker rats display symptoms of metabolic disorder or Type II diabetes. This study examined the effects of vibration in obese and lean rats. Zucker rats were exposed to 4 h of vibration for 10 consecutive days at a frequency of 125 Hz and acceleration of 49 m/s2 for 10 consecutive days. Sensory function was checked using transcutaneous electrical stimulation on days 1, 5 and 9 of the exposure. Once the study was complete the ventral tail nerves, dorsal root ganglia and spinal cord were dissected, and levels of various transcripts involved in sensorineural dysfunction were measured. Sensorineural dysfunction was assessed using transcutaneous electrical stimulation. Obese Zucker rats displayed very few changes in sensorineural function. However they did display significant changes in transcript levels for factors involved in synapse formation, peripheral nerve remodeling, and inflammation. The changes in transcript levels suggested that obese Zucker rats had some level of sensory nerve injury prior to exposure, and that exposure to vibration activated pathways involved in injury and re-innervation. PMID:26433044

  5. The effects of repetitive vibration on sensorineural function: biomarkers of sensorineural injury in an animal model of metabolic syndrome.

    PubMed

    Kiedrowski, Megan; Waugh, Stacey; Miller, Roger; Johnson, Claud; Krajnak, Kristine

    2015-11-19

    Exposure to hand-transmitted vibration in the work-place can result in the loss of sensation and pain in workers. These effects may be exacerbated by pre-existing conditions such as diabetes or the presence of primary Raynaud's phenomena. The goal of these studies was to use an established model of vibration-induced injury in Zucker rats. Lean Zucker rats have a normal metabolic profile, while obese Zucker rats display symptoms of metabolic disorder or Type II diabetes. This study examined the effects of vibration in obese and lean rats. Zucker rats were exposed to 4h of vibration for 10 consecutive days at a frequency of 125 Hz and acceleration of 49 m/s(2) for 10 consecutive days. Sensory function was checked using transcutaneous electrical stimulation on days 1, 5 and 9 of the exposure. Once the study was complete the ventral tail nerves, dorsal root ganglia and spinal cord were dissected, and levels of various transcripts involved in sensorineural dysfunction were measured. Sensorineural dysfunction was assessed using transcutaneous electrical stimulation. Obese Zucker rats displayed very few changes in sensorineural function. However they did display significant changes in transcript levels for factors involved in synapse formation, peripheral nerve remodeling, and inflammation. The changes in transcript levels suggested that obese Zucker rats had some level of sensory nerve injury prior to exposure, and that exposure to vibration activated pathways involved in injury and re-innervation.

  6. Vibration-type particle separation device with piezoceramic vibrator

    NASA Astrophysics Data System (ADS)

    Ooe, Katsutoshi; Doi, Akihiro

    2008-12-01

    During hemanalysis, it is necessary to separate blood cells from whole blood. Many blood separation methods, for example, centrifugation and filtering, are in practical use. However, the use of these methods involves problems from the perspectives of processing speed and processing volume. We develop new types of blood separation devices that use piezo-ceramic vibrators. The first device uses a capillary. One end of the capillary is fixed to the device frame, and the other is fixed to a piezo-ceramic vibrator. The vibrator transmits bending waves to the capillary. This device can process only a small amount of solution; therefore, it is not suitable for hemanalysis. In order to solve this problem, we developed a second device; this device has a pair of thin glass plates with a small gap as a substitute for the capillary used in the first device. These devices are based on the fact that particles heavier than water move toward transverse velocity antinodes while those lighter than water move toward velocity nodes. In this report, we demonstrate the highspeed separation of silica microbeads and 50-vol% glycerol water by using these devices. The first device can separate the abovementioned solution within 3 min while the second can separate it within 1 min. Both devices are driven by a rectangular wave of 15 to 20 Vpp. Furthermore, it has been confirmed that red blood cells are separated from diluted whole blood using the first device within approximately 1 min. These devices have transparency, so they can compose as the analysis system with the chemical analyzer easily.

  7. Structural vibrations of buried land mines

    NASA Astrophysics Data System (ADS)

    Zagrai, Andrei; Donskoy, Dimitri; Ekimov, Alexander

    2005-12-01

    Buried landmines exhibit complex structural vibrations, which are dependent on interaction between soil and mines as well as on their respective properties. This paper presents experimental and theoretical studies of multimodal vibrations of buried mines and discusses the effects of burial depth and soil properties on dynamics of the soil-mine system. The two-dimensional model of the soil-mine system that accounts for soil-coupled mine's multiple vibration modes and spatial distribution of vibrations over the soil surface is introduced. The model was tested using experiments with the plastic mine simulant. The study reveals that the soil shear stiffness is one of the key governing parameters determining the resonance vibration frequency and the amplitude of the soil-mine system. Burial depth, soil moisture, and consolidation are among factors leading to the increase of the soil shear stiffness, therefore effectively influencing modal vibrations of buried mines.

  8. Actively controlled vibration welding system and method

    DOEpatents

    Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

    2013-04-02

    A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

  9. Vibrational diagnostics of rotating machinery malfunctions

    NASA Astrophysics Data System (ADS)

    Muszynska, A.

    The diagnostics of rotating machinery malfunction, using vibration data in correlation with operational process data is outlined. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are emphasized. The basic principles of machinery diagnostics, and several specific malfunction symptoms supported by simple mathematical models are given. These malfunctions include unbalance, excessive radial preload, rotor to stator rubbing, fluid induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions. Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics of machinery is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are discussed. The basic instrumentation for machine monitoring is outlined.

  10. Coupling between plate vibration and acoustic radiation

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1992-01-01

    A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far-field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far-field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.

  11. Shock and vibration tests of uranium mononitride fuel pellets for a space power nuclear reactor

    NASA Technical Reports Server (NTRS)

    Adams, D. W.

    1972-01-01

    Shock and vibration tests were conducted on cylindrically shaped, depleted, uranium mononitride (UN) fuel pellets. The structural capabilities of the pellets were determined under exposure to shock and vibration loading which a nuclear reactor may encounter during launching into space. Various combinations of diametral and axial clearances between the pellets and their enclosing structures were tested. The results of these tests indicate that for present fabrication of UN pellets, a diametral clearance of 0.254 millimeter and an axial clearance of 0.025 millimeter are tolerable when subjected to launch-induced loads.

  12. Studies Of Residual Flexibility And Vibration Testing

    NASA Technical Reports Server (NTRS)

    Admire, John R.; Tinker, Michael L.; Bookout, Paul S.; Ivey, Edward W.

    1995-01-01

    Collection of reports presents theoretical and experimental studies in which concept of residual flexibility applied to modal vibration testing and verification of mathematical models of vibrations of flexible structure constrained by another structure. "Residual flexibility" denotes that part of interface flexibility due to mode shapes out of frequency range of test. Studies directed toward assessing residual-flexibility approach as substitute for fixed-base vibrational testing of payloads installed in spacecraft.

  13. Axisymmetric vibrations of layered tapered plates

    NASA Astrophysics Data System (ADS)

    Navaneethakrishnan, P. V.; Chandrasekaran, K.; Ravisrinivas, N.

    1992-12-01

    The study of Navaneethakrishnan and Chandrasekaran (1989) on axisymmetric free vibrations of layered annular plates is extended to the vibrations of layered annular plates whose thickness can vary as the radial distance from the arbitrary concentric circle. Numerical results are presented, showing the relationship between the circular frequency of the plate vibration and the ratio between the inner and the outer radii of the plate.

  14. Research In Diagnosing Bearing Defects From Vibrations

    NASA Technical Reports Server (NTRS)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Report describes research in bearing-defect signature analysis - use of vibration-signal analysis to diagnose defects in roller and ball bearings. Experiments performed on bearings in good condition and other bearings in which various parts scratched to provide known defects correlated with vibration signals. Experiments performed on highly instrumented motor-driven rotor assembly at speeds up to 10,050 r/min, using accelerometers, velocity probes, and proximity sensors mounted at various locations on assembly to measure vibrations.

  15. Centaur liquid oxygen boost pump vibration test

    NASA Technical Reports Server (NTRS)

    Tang, H. M.

    1975-01-01

    The Centaur LOX boost pump was subjected to both the simulated Titan Centaur proof flight and confidence demonstration vibration test levels. For each test level, both sinusoidal and random vibration tests were conducted along each of the three orthogonal axes of the pump and turbine assembly. In addition to these tests, low frequency longitudinal vibration tests for both levels were conducted. All tests were successfully completed without damage to the boost pump.

  16. Ground vibrations from heavy freight trains

    NASA Astrophysics Data System (ADS)

    Dawn, T. M.

    1983-03-01

    Ground vibration from heavy freight trains on good quality welded track are found to have only a weak dependence on train speed above 30 km/h. At the site on which these tests were carried out a critical speed was found at which the vibration reached a peak. The frequencies of vibration produced appear to be functions of track and vehicle dimensions and the critical speed occurs at the coincidence of sleeper passage frequency and the total vehicle on track resonance frequency.

  17. Vibrational Control of a Nonlinear Elastic Panel

    NASA Technical Reports Server (NTRS)

    Chow, P. L.; Maestrello, L.

    1998-01-01

    The paper is concerned with the stabilization of the nonlinear panel oscillation by an active control. The control is actuated by a combination of additive and parametric vibrational forces. A general method of vibrational control is presented for stabilizing panel vibration satisfying a nonlinear beam equation. To obtain analytical results, a perturbation technique is used in the case of weak nonlinearity. Possible application to other types of problems is briefly discussed.

  18. Communication: Creation of molecular vibrational motions via the rotation-vibration coupling

    SciTech Connect

    Shu, Chuan-Cun; Henriksen, Niels E.

    2015-06-14

    Building on recent advances in the rotational excitation of molecules, we show how the effect of rotation-vibration coupling can be switched on in a controlled manner and how this coupling unfolds in real time after a pure rotational excitation. We present the first examination of the vibrational motions which can be induced via the rotation-vibration coupling after a pulsed rotational excitation. A time-dependent quantum wave packet calculation for the HF molecule shows how a slow (compared to the vibrational period) rotational excitation leads to a smooth increase in the average bond length whereas a fast rotational excitation leads to a non-stationary vibrational motion. As a result, under field-free postpulse conditions, either a stretched stationary bond or a vibrating bond can be created due to the coupling between the rotational and vibrational degrees of freedom. The latter corresponds to a laser-induced breakdown of the adiabatic approximation for rotation-vibration coupling.

  19. Communication: Creation of molecular vibrational motions via the rotation-vibration coupling.

    PubMed

    Shu, Chuan-Cun; Henriksen, Niels E

    2015-06-14

    Building on recent advances in the rotational excitation of molecules, we show how the effect of rotation-vibration coupling can be switched on in a controlled manner and how this coupling unfolds in real time after a pure rotational excitation. We present the first examination of the vibrational motions which can be induced via the rotation-vibration coupling after a pulsed rotational excitation. A time-dependent quantum wave packet calculation for the HF molecule shows how a slow (compared to the vibrational period) rotational excitation leads to a smooth increase in the average bond length whereas a fast rotational excitation leads to a non-stationary vibrational motion. As a result, under field-free postpulse conditions, either a stretched stationary bond or a vibrating bond can be created due to the coupling between the rotational and vibrational degrees of freedom. The latter corresponds to a laser-induced breakdown of the adiabatic approximation for rotation-vibration coupling.

  20. The multi-axis vibration environment and man.

    PubMed

    Lovesey, E J

    1970-12-01

    Many investigations into the effects of vibration on man have been performed since Mallock's first study of London Underground vibrations in 1902. The vibration research has tended to be confined to the vertical (heave) axis, yet recent experiments have indicated that low frequency vibration along the lateral (sway) axis has a greater adverse effect upon comfort and performance. Measurements of the vibration environments in current forms of transport including motor vehicles, hovercraft and aircraft etc have shown that appreciable quantities of vibration along all three axes exist. Further vibration research should consider the effects of multi-axis vibrations upon man rather than limit tests to single axis vibration. PMID:15676336

  1. Exposure chamber

    DOEpatents

    Moss, Owen R.; Briant, James K.

    1983-01-01

    An exposure chamber includes an imperforate casing having a fluid inlet at the top and an outlet at the bottom. A single vertical series of imperforate trays is provided. Each tray is spaced on all sides from the chamber walls. Baffles adjacent some of the trays restrict and direct the flow to give partial flow back and forth across the chambers and downward flow past the lowermost pan adjacent a central plane of the chamber.

  2. Vibrational energy transfer in high explosives: Nitromethane

    SciTech Connect

    Hong, X.; Hill, J.R.; Dlott, D.D.

    1996-03-01

    Time resolved vibrational spectroscopy with picosecond tunable mid-infrared pulses is used to measure the rates and investigate the detailed mechanisms of multiphonon up-pumping and vibrational cooling in a condensed high explosive, nitromethane. Both processes occur on the 100 ps time scale under ambient conditions. The mechanisms involve sequential climbing or descending the ladder of molecular vibrations. Efficient intermolecular vibrational energy transfer from various molecules to the symmetric stretching excitation of NO2 is observed. The implications of these measurements for understanding shock initiation to detonation and the sensitivities of energetic materials to shock initiation are discussed briefly.

  3. Noise and vibration ride comfort criteria

    NASA Technical Reports Server (NTRS)

    Dempsey, T. K.; Leatherwood, J. D.; Clevenson, S. A.

    1976-01-01

    A program is underway at Langley Research Center to develop a comprehensive ride quality model based upon the various physical and psychological factors that most affect passenger ride comfort. Two of the most important factors, namely, vibration and noise were studied to (1) determine whether composite or separate noise and vibration criteria are needed for the prediction of ride quality, (2) determine a noise correction for the previously-defined vibration criteria of the ride quality model, (3) assess whether these noise corrections depend on the nature of the vibration stimuli, i.e., deterministic as opposed to random, and (4) specify noise-vibration criteria for this combined environment. The stimuli for the study consisted of octave bands of noise centered at 500 or 2000 Hz and vertical vibrations composed of either 5 Hz sinusoidal vibration or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. The noise stimuli were presented at levels ranging from ambient to 95 dB(A) and the vibrations at levels ranging from 0.02 to 0.13 g-rms.

  4. Analysis of potential helicopter vibration reduction concepts

    NASA Technical Reports Server (NTRS)

    Landgrebe, A. J.; Davis, M. W.

    1985-01-01

    Results of analytical investigations to develop, understand, and evaluate potential helicopter vibration reduction concepts are presented in the following areas: identification of the fundamental sources of vibratory loads, blade design for low vibration, application of design optimization techniques, active higher harmonic control, blade appended aeromechanical devices, and the prediction of vibratory airloads. Primary sources of vibration are identified for a selected four-bladed articulated rotor operating in high speed level flight. The application of analytical design procedures and optimization techniques are shown to have the potential for establishing reduced vibration blade designs through variations in blade mass and stiffness distributions, and chordwise center-of-gravity location.

  5. Inertia-Wheel Vibration-Damping System

    NASA Technical Reports Server (NTRS)

    Fedor, Joseph V.

    1990-01-01

    Proposed electromechanical system would damp vibrations in large, flexible structure. In active vibration-damping system motors and reaction wheels at tips of appendages apply reaction torques in response to signals from accelerometers. Velocity signal for vibrations about one axis processes into control signal to oppose each of n vibrational modes. Various modes suppressed one at a time. Intended primarily for use in spacecraft that has large, flexible solar panels and science-instrument truss assembly, embodies principle of control interesting in its own right and adaptable to terrestrial structures, vehicles, and instrument platforms.

  6. Experiments In Characterizing Vibrations Of A Structure

    NASA Technical Reports Server (NTRS)

    Yam, Yeung; Hadaegh, Fred Y.; Bayard, David S.

    1993-01-01

    Report discusses experiments conducted to test methods of identification of vibrational and coupled rotational/vibrational modes of flexible structure. Report one in series that chronicle development of integrated system of methods, sensors, actuators, analog and digital signal-processing equipment, and algorithms to suppress vibrations in large, flexible structure even when dynamics of structure partly unknown and/or changing. Two prior articles describing aspects of research, "Autonomous Frequency-Domain Indentification" (NPO-18099), and "Automated Characterization Of Vibrations Of A Structure" (NPO-18141).

  7. Coal storage hopper with vibrating screen agitator

    DOEpatents

    Daw, Charles S.; Lackey, Mack E.; Sy, Ronald L.

    1984-01-01

    The present invention is directed to a vibrating screen agitator in a coal storage hopper for assuring the uniform feed of coal having sufficient moisture content to effect agglomeration and bridging thereof in the coal hopper from the latter onto a conveyor mechanism. The vibrating screen agitator is provided by a plurality of transversely oriented and vertically spaced apart screens in the storage hopper with a plurality of vertically oriented rods attached to the screens. The rods are vibrated to effect the vibration of the screens and the breaking up of agglomerates in the coal which might impede the uniform flow of the coal from the hopper onto a conveyer.

  8. Vibrational dynamics of crystalline L-alanine

    SciTech Connect

    Bordallo, H.N.; Eckert, J.; Barthes, M.

    1997-11-01

    The authors report a new, complete vibrational analysis of L-alanine and L-alanine-d{sub 4} which utilizes IINS intensities in addition to frequency information. The use of both isotopomers resulted in a self-consistent force field for and assignment of the molecular vibrations in L-alanine. Some details of the calculation as well as a comparison of calculated and observed IINS spectra are presented. The study clarifies a number of important issues on the vibrational dynamics of this molecule and presents a self-consistent force field for the molecular vibrations in crystalline L-alanine.

  9. Surface acoustic wave (SAW) vibration sensors.

    PubMed

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  10. Stability of a liquid bridge under vibration

    NASA Astrophysics Data System (ADS)

    Benilov, E. S.

    2016-06-01

    We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global timescale, respectively, we employ the method of multiple scales to derive a set of asymptotic equations. The set is then used to examine the stability of a bridge of an almost cylindrical shape. It is shown that, if acting alone, gravity is a destabilizing influence, whereas vibration can weaken it or even eliminate altogether. Thus, counter-intuitively, vibration can stabilize an otherwise unstable capillary structure.

  11. Stability of a liquid bridge under vibration.

    PubMed

    Benilov, E S

    2016-06-01

    We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global timescale, respectively, we employ the method of multiple scales to derive a set of asymptotic equations. The set is then used to examine the stability of a bridge of an almost cylindrical shape. It is shown that, if acting alone, gravity is a destabilizing influence, whereas vibration can weaken it or even eliminate altogether. Thus, counter-intuitively, vibration can stabilize an otherwise unstable capillary structure.

  12. Moire interferometry for vibration analysis of plates

    NASA Astrophysics Data System (ADS)

    Asundi, A.; Cheung, M. T.

    1987-12-01

    Moire interferometry is used to locate nodal regions and measure vibration amplitudes of sinusoidally vibrating square plates. The high sensitivity afforded by this technique makes possible the study of plate vibrations at high frequencies and low amplitudes. The initial pattern is modulated by the zero-order Bessel function representing the vibratory motion. The fringe (or fringes) with best contrast indicate the nodal regions, while the higher order fringes, describing loci of points vibrating with the same amplitude, have decreasing contrast which is improved by spatial filtering.

  13. Surface acoustic wave (SAW) vibration sensors.

    PubMed

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit. PMID:22247694

  14. High force vibration testing with wide frequency range

    SciTech Connect

    Romero, Edward F.; Jepsen, Richard A.; Gregory, Danny Lynn

    2013-04-02

    A shaker assembly for vibration testing includes first and second shakers, where the first shaker includes a piezo-electric material for generating vibration. A support structure permits a test object to be supported for vibration of the test object by both shakers. An input permits an external vibration controller to control vibration of the shakers.

  15. Vibration modes of giant gravitons

    SciTech Connect

    Das, Sumit R.; Jevicki, Antal; Mathur, Samir D.

    2001-01-15

    We examine the spectrum of small vibrations of giant gravitons when the gravitons expand in anti--de Sitter space and when they expand on the sphere. For any given angular harmonic, the modes are found to have frequencies related to the curvature length scale of the background; these frequencies are independent of radius (and hence angular momentum) of the brane itself. This implies that the holographic dual theory must have, in a given R charge sector, low-lying non-BPS excitations with level spacings independent of the R charge.

  16. Vibrational Spectroscopy of Chromatographic Interfaces

    SciTech Connect

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  17. Multivariate Analysis of Ladle Vibration

    NASA Astrophysics Data System (ADS)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle

    2016-08-01

    The homogeneity of composition and uniformity of temperature of the steel melt before it is transferred to the tundish are crucial in making high-quality steel product. The homogenization process is performed by stirring the melt using inert gas in ladles. Continuous monitoring of this process is important to make sure the action of stirring is constant throughout the ladle. Currently, the stirring process is monitored by process operators who largely rely on visual and acoustic phenomena from the ladle. However, due to lack of measurable signals, the accuracy and suitability of this manual monitoring are problematic. The actual flow of argon gas to the ladle may not be same as the flow gage reading due to leakage along the gas line components. As a result, the actual degree of stirring may not be correctly known. Various researchers have used one-dimensional vibration, and sound and image signals measured from the ladle to predict the degree of stirring inside. They developed online sensors which are indeed to monitor the online stirring phenomena. In this investigation, triaxial vibration signals have been measured from a cold water model which is a model of an industrial ladle. Three flow rate ranges and varying bath heights were used to collect vibration signals. The Fast Fourier Transform was applied to the dataset before it has been analyzed using principal component analysis (PCA) and partial least squares (PLS). PCA was used to unveil the structure in the experimental data. PLS was mainly applied to predict the stirring from the vibration response. It was found that for each flow rate range considered in this study, the informative signals reside in different frequency ranges. The first latent variables in these frequency ranges explain more than 95 pct of the variation in the stirring process for the entire single layer and the double layer data collected from the cold model. PLS analysis in these identified frequency ranges demonstrated that the latent

  18. Vibration analysis using moire interferometry

    NASA Astrophysics Data System (ADS)

    Asundi, A.; Cheung, M. T.

    The present use of moire interferometry for low amplitude vibration and analysis demonstrates the possibility of obtaining out-of-plane displacement contours whose sensitivity is comparable to that of holographic methods. A major advantage of the present system, is the obviation of prior knowledge of resonant frequencies, as called for in time-average holography. The experimental apparatus employed encompasses a laser beam, a parabolic mirror, a high frequency (600 line/mm) grating, and a camera, in addition to the test model.

  19. Longitudinal-torsional vibration source consisting of two transducers with different vibration modes

    NASA Astrophysics Data System (ADS)

    Asami, Takuya; Miura, Hikaru

    2016-07-01

    The planar vibration locus is applicable to, for example, ultrasonic welding, ultrasonic machining, and ultrasonic polishing. In a previous study, we obtained the planar locus using an ultrasonic longitudinal-torsional vibration source that contained a vibration converter comprising diagonal slits to drive two frequencies. It was difficult to obtain only longitudinal or torsional vibration when using an ultrasonic complex vibration source with diagonal slits. Therefore, the versatility of the ultrasonic complex vibration source with diagonal slits was low. We have developed an ultrasonic longitudinal-torsional vibration source in which the longitudinal-torsional vibration can be controlled. The requirements for an ultrasonic vibration source were longitudinal-torsional vibration control and that the source has a planar locus. In this paper, we investigate a new type of vibration source that satisfies these requirements. It consists of two transducers, a longitudinal transducer and a torsional transducer, attached to the ends of a uniform rod with a length of one wavelength of the propagating vibration.

  20. Theoretical prediction of vibrational spectra

    NASA Astrophysics Data System (ADS)

    Niu, Zefu; Dunn, Kevin M.; Boggs, James E.

    The complete harmonic force field and the diagonal and first off-diagonal cubic constants of aniline have been calculated ab initio using a 4-21 basis set augmented by addition of d functions to the nitrogen atom. The force constants were then scaled using scale factors optimized previously to give the best fit to the similarly computed vibrational spectra of benzene and its deuterated isotopomers. The vibrational spectra of aniline, aniline-NHD, and aniline-ND2 were then calculated from this scaled quantum mechanical (SQM) force field and compared with experimentally observed spectra. Several corrections were made to previously proposed empirical spectral assignments. Because of computational difficulties, no definitive statement can be made about the torsion or inversion modes of the amino group. Aside from these and the C-H stretching frequencies for which the detailed assignment is still quite uncertain, the average deviation between the observed frequencies and those obtained entirely from the scaled computed force field is 9·1 cm-1. Dipole moment derivatives and infrared absorption intensities were also calculated, but these are of lower accuracy.

  1. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2005-10-31

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the rebuilding of the prototype using the improved valve design described in the Jan-March report1. Most of the components have been received and assembly was nearly complete at the end of the period. Testing started in October and results will be submitted in the next report. The field testing component of this Phase has been rethought. The current plan is to adapt the laboratory prototype for use in a drilling laboratory and run a series of controlled drilling tests with and without the DVMCS. This should give a more quantitative evaluation of its value, which will help us sign a commercialization partner. While this testing is underway, we will order and begin machining parts for full field prototypes to be use in Phase III. A modification application is being submitted in October to reflect these changes.

  2. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2005-07-27

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the rebuilding of the prototype using the improved valve design described in the last report. Most of the components have been received and assembly has begun. Testing is expected to resume in August. In April, a paper was presented at the American Association of Drilling Engineers National Technical Conference in Houston. The paper was well received, and several oilfield service and supply companies sent inquiries regarding commercial distribution of the system. These are currently being pursued, but none have yet been finalized.

  3. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2006-01-17

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the testing of the rebuilt laboratory prototype and its conversion into a version that will be operable in the drilling tests at TerraTek Laboratories. In addition, formations for use in these tests were designed and constructed, and a test protocol was developed. The change in scope and no-cost extension of Phase II to January, 2006, described in our last report, were approved. The tests are scheduled to be run during the week of January 23, and should be completed before the end of the month.

  4. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2006-09-30

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II were: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Phase II concluded on January 31, 2006, and the final report was issued. Work on Phase III of the project began during the previous quarter. Efforts this quarter have focused on the manufacture of the prototype and precommercial parts, field test planning and commercialization. The current extreme lead times quoted by oilfield machine shops for collar components, will delay the deployment of the field prototypes. The delivery date for five critical parts from one supplier has slipped to late November, which will preclude deployment for a field test before late December or early January. We are exploring whether we can take the partially made parts and complete them earlier in our own shop.

  5. TIME-RESOLVED VIBRATIONAL SPECTROSCOPY

    SciTech Connect

    Andrei Tokmakoff, MIT; Paul Champion, Northeastern University; Edwin J. Heilweil, NIST; Keith A. Nelson, MIT; Larry Ziegler, Boston University

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE’s Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all five of DOE’s grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  6. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2005-01-28

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. The redesign and upgrade of the laboratory prototype was completed on schedule and it was assembled during the last period. Testing was begin during the first week of October. Initial results indicated that the dynamic range of the damping was less than predicted and that the maximum damping was also less than required. A number of possible explanations for these results were posited, and test equipment was acquired to evaluate the various hypotheses. Testing was just underway at the end of this period.

  7. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-10-29

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. Phase II began on June 1, and the first month's effort were reported in the seventh quarterly report on the project.1 The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. The redesign and upgrade of the laboratory prototype was completed on schedule during this period, and assembly was complete at the end of this period. Testing will begin during the first week of October. This aspect of the project is thus approximately six weeks behind schedule. Design of the field prototype is progressing per schedule.

  8. Criminal exposure.

    PubMed

    1999-09-01

    In August, an HIV-positive man plead guilty to sexually assaulting a 14-year-old boy. The sleeping boy awoke to find [name removed] sexually assaulting him, while watching a pornographic video. [Name removed] plead guilty to the assault with intent to rape a child. In addition, [name removed] received three counts of indecent assault and battery on a child, and exposure of pornographic material to a minor. [Name removed] will remain on probation for five years, although the prosecution had recommended sentencing [name removed] to four or five years in prison. The boy continues to be tested for HIV.

  9. Detection of light and vibration modulates bioluminescence intensity in the glowworm, Arachnocampa flava.

    PubMed

    Mills, Rebecca; Popple, Julie-Anne; Veidt, Martin; Merritt, David John

    2016-04-01

    Glowworms are larval fungus gnats that emit light from a specialised abdominal light organ. The light attracts small arthropod prey to their web-like silk snares. Larvae glow throughout the night and can modulate their bioluminescence in response to sensory input. To better understand light output regulation and its ecological significance, we examined the larvae's reaction to light exposure, vibration and sound. Exposure to a 5-min light pulse in the laboratory causes larvae to exponentially decrease their light output over 5-10 min until they completely switch off. They gradually return to pre-exposure levels but do not show a rebound. Larvae are most sensitive to ultraviolet light, then blue, green and red. Vibration of the larval snares results in a several-fold increase in bioluminescence over 20-30 s, followed by an exponential return to pre-exposure levels over 15-30 min. Under some conditions, larvae can respond to vibration by initiating bioluminescence when they are not glowing; however, the response is reduced compared to when they are glowing. We propose that inhibitory and excitatory mechanisms combine to modulate bioluminescence intensity by regulating biochemical reactions or gating the access of air to the light organ.

  10. Selective probe of the morphology and local vibrations at carbon nanoasperities

    SciTech Connect

    Fujimori, Toshihiko; Endo, Morinobu; Kaneko, Katsumi; Urita, Koki; Moriguchi, Isamu; Tomanek, David; Ohba, Tomonori

    2012-02-14

    We introduce a way to selectively probe local vibration modes at nanostructured asperities such as tips of carbon nanohorns. Our observations benefit from signal amplification in surface-enhanced Raman scattering (SERS) at sites near a silver surface. We observe nanohorn tip vibration modes in the range 200-500 cm{sup -1}, which are obscured in regular Raman spectra. Ab initio density functional calculations assign modes in this frequency range to local vibrations at the nanohorn cap resembling the radial breathing mode of fullerenes. Careful interpretation of our SERS spectra indicates presence of caps with 5 or 6 pentagons, which are chemically the most active sites. Changes in the peak intensities and frequencies with time indicate that exposure to laser irradiation may cause structural rearrangements at the cap.

  11. Sound and structural vibration - A review

    NASA Astrophysics Data System (ADS)

    Fahy, F. J.

    The fundamental principles of fluid-structure interaction are reviewed. Modern fields of application are discussed with attention given to sound radiation from vibrating structures, fluid loading of vibrating structures, airborne sound transmission through structural partitions, and acoustically induced response of structures. Theoretical and experimental techniques are outined with particular emphasis on recent developments.

  12. Vibration therapy: clinical applications in bone

    PubMed Central

    Thompson, William R.; Yen, Sherwin S.; Rubin, Janet

    2015-01-01

    Purpose of review The musculoskeletal system is largely regulated through dynamic physical activity and is compromised by cessation of physical loading. There is a need to recreate the anabolic effects of loading on the musculoskeletal system, especially in frail individuals who cannot exercise. Vibration therapy is designed to be a nonpharmacological analogue of physical activity, with an intention to promote bone and muscle strength. Recent findings Animal and human studies suggest that high-frequency, low-magnitude vibration therapy improves bone strength by increasing bone formation and decreasing bone resorption. There is also evidence that vibration therapy is useful in treating sarcopenia, which confounds skeletal fragility and fall risk in aging. Enhancement of skeletal and muscle strength involves regulating the differentiation of mesenchymal stem cells to build these tissues; mesenchymal stem cell lineage allocation is positively promoted by vibration signals. Summary Vibration therapy may be useful as a primary treatment as well as an adjunct to both physical and pharmacological treatments, but future studies must pay close attention to compliance and dosing patterns, and importantly, the vibration signal, be it low-intensity vibration (<1g) appropriate for treatment of frail individuals or high-intensity vibration (>1g) marketed as a training exercise. PMID:25354044

  13. Automated Characterization Of Vibrations Of A Structure

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Yam, Yeung; Mettler, Edward; Hadaegh, Fred Y.; Milman, Mark H.; Scheid, Robert E.

    1992-01-01

    Automated method of characterizing dynamical properties of large flexible structure yields estimates of modal parameters used by robust control system to stabilize structure and minimize undesired motions. Based on extraction of desired modal and control-design data from responses of structure to known vibrational excitations. Applicable to terrestrial structures where vibrations are important - aircraft, buildings, bridges, cranes, and drill strings.

  14. Benefits of Spacecraft Level Vibration Testing

    NASA Technical Reports Server (NTRS)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  15. 14 CFR 33.43 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the...

  16. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs,...

  17. 33 CFR 159.103 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Vibration test. 159.103 Section 159.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The...

  18. 14 CFR 33.43 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the...

  19. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs,...

  20. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs,...

  1. 33 CFR 159.103 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Vibration test. 159.103 Section 159.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The...

  2. 14 CFR 33.43 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the...

  3. Granular avalanches down inclined and vibrated planes

    NASA Astrophysics Data System (ADS)

    Gaudel, Naïma; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Jenny, Mathieu; Skali-Lami, Salaheddine

    2016-09-01

    In this article, we study granular avalanches when external mechanical vibrations are applied. We identify conditions of flow arrest and compare with the ones classically observed for nonvibrating granular flows down inclines [Phys. Fluids 11, 542 (1999), 10.1063/1.869928]. We propose an empirical law to describe the thickness of the deposits with the inclination angle and the vibration intensity. The link between the surface velocity and the depth of the flow highlights a competition between gravity and vibrations induced flows. We identify two distinct regimes: (a) gravity-driven flows at large angles where vibrations do not modify dynamical properties but the deposits (scaling laws in this regime are in agreement with the literature for nonvibrating granular flows) and (b) vibrations-driven flows at small angles where no flow is possible without applied vibrations (in this last regime, the flow behavior can be properly described by a vibration induced activated process). We show, in this study, that granular flows down inclined planes can be finely tuned by external mechanical vibrations.

  4. Statistical quality control through overall vibration analysis

    NASA Astrophysics Data System (ADS)

    Carnero, M. a. Carmen; González-Palma, Rafael; Almorza, David; Mayorga, Pedro; López-Escobar, Carlos

    2010-05-01

    The present study introduces the concept of statistical quality control in automotive wheel bearings manufacturing processes. Defects on products under analysis can have a direct influence on passengers' safety and comfort. At present, the use of vibration analysis on machine tools for quality control purposes is not very extensive in manufacturing facilities. Noise and vibration are common quality problems in bearings. These failure modes likely occur under certain operating conditions and do not require high vibration amplitudes but relate to certain vibration frequencies. The vibration frequencies are affected by the type of surface problems (chattering) of ball races that are generated through grinding processes. The purpose of this paper is to identify grinding process variables that affect the quality of bearings by using statistical principles in the field of machine tools. In addition, an evaluation of the quality results of the finished parts under different combinations of process variables is assessed. This paper intends to establish the foundations to predict the quality of the products through the analysis of self-induced vibrations during the contact between the grinding wheel and the parts. To achieve this goal, the overall self-induced vibration readings under different combinations of process variables are analysed using statistical tools. The analysis of data and design of experiments follows a classical approach, considering all potential interactions between variables. The analysis of data is conducted through analysis of variance (ANOVA) for data sets that meet normality and homoscedasticity criteria. This paper utilizes different statistical tools to support the conclusions such as chi squared, Shapiro-Wilks, symmetry, Kurtosis, Cochran, Hartlett, and Hartley and Krushal-Wallis. The analysis presented is the starting point to extend the use of predictive techniques (vibration analysis) for quality control. This paper demonstrates the existence

  5. Noise-induced hearing loss in relation to vibration-induced white finger in chain-saw workers.

    PubMed

    Miyakita, T; Miura, H; Futatsuka, M

    1987-02-01

    From the viewpoint of the etiologies of noise-induced permanent threshold shift (NIPTS) and vibration-induced white finger (VWF), the association between VWF and hearing loss was examined among 499 chain-saw workers who underwent a compulsory health examination for vibration syndrome. They were classified by age, duration of noise and vibration exposure, and the severity of VWF. The severity of VWF was evaluated according to the following criteria: no prior history; VWF history, but symptoms had disappeared; VWF present but appearing rarely; frequent appearance of VWF (more than 20 times per winter season). In three age groups (ie, 40-49, 50-59, 60-69 years) with 5-9 years of exposure, the chainsaw workers with VWF had a significantly greater hearing loss at higher frequencies than those without VWF. However, in the 10- to 14-year exposure groups, a significant difference was not found between the VWF and non-VWF groups, except that the 50- to 59-year age groups showed a significant difference in mean age. It was suggested that interindividual differences in susceptibility to noise and vibration may be the reason for the synergistic effects of noise and vibration.

  6. Optimization design of vibration characteristics of ship composite brace with rigid vibration isolation mass

    NASA Astrophysics Data System (ADS)

    Wang, Qiangyong; Yao, Xiongliang; Yu, Danzhu; Pang, Fuzhen

    2011-06-01

    In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

  7. Effects of vibration excitation methodology and configuration of an acoustic needle on its tip vibration.

    PubMed

    Li, Ning; Hu, Junhui

    2013-04-01

    One of design purposes of an acoustic needle is to obtain a big vibration displacement at its tip. In this paper, vibration characteristics of the tip of the acoustic needle driven by a sandwich type ultrasonic transducer, is investigated to obtain the guidelines for increasing the tip vibration. It is found that the tip vibration can be increased by employing acoustic needles with proper vibration excitation structure and configuration. The effective measures include using a sandwich type piezoelectric transducer with flexurally vibrating end plates and an acoustic needle with conical tip section, decreasing the length of vibration excitation section at the needle root, bonding the needle root at a proper location of the transducer end plate, and tuning the length ratio of the conical tip section to the whole needle. PMID:23294988

  8. Vibrational spectroscopy in high temperature dense fluids

    SciTech Connect

    Moore, D.S.; Schmidt, S.C.

    1992-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) in conjunction with a two-stage light-gas gun has been used to obtain vibrational spectra of shock-compressed liquid N{sub 2}, O{sub 2}, CO, and their mixtures, as well as liquid N{sub 2}O. The experimental spectra are compared to spectra calculated using a semiclassical model for CARS intensities to obtain vibrational frequencies, peak Raman susceptibilities, and linewidths. The derived spectroscopic parameters suggest thermal equilibrium of the vibrational populations is established in less than a few nanoseconds after shock passage. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations. The variation of the vibrational frequency shift at pressure with species concentration in mixtures is investigated.

  9. Vibration suppression of satellites using multifunctional platforms

    NASA Astrophysics Data System (ADS)

    Antin, Nicolas; Russ, Richard; Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2009-03-01

    This research focuses on a finite element analysis of active vibration suppression capabilities of a smart composite platform, which is a structural interface between a satellite main thruster and its structure and possesses simultaneous precision positioning and vibration suppression capabilities for thrust vector control of a satellite. First, the combined system of the smart composite platform and the satellite structure are briefly described followed by the finite element modeling and simulations. The smart platform piezoelectric patches and stacks material properties modeling, for the finite element analysis, are developed consistent with the manufacturer data. Next, a vibration suppression scheme, based on the modal analysis, is presented and used in vibration suppression analysis of satellite structures of the thrust vector under the thruster-firing excitation. The approach introduced here is an effective technique for the design of smart structures with complex geometry to study their MIMO active vibration suppression capabilities.

  10. Vibrational dynamics of ice in reverse micelles.

    PubMed

    Dokter, Adriaan M; Petersen, Christian; Woutersen, Sander; Bakker, Huib J

    2008-01-28

    The ultrafast vibrational dynamics of HDO:D(2)O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is studied to characterize the micellar structure. Small reverse micelles with a water content up to approximately 150 water molecules contain an amorphous form of ice that shows remarkably different vibrational dynamics compared to bulk hexagonal ice. The micellar amorphous ice has a much longer vibrational lifetime than bulk hexagonal ice and micellar liquid water. The vibrational lifetime is observed to increase linearly from 0.7 to 4 ps with the resonance frequency ranging from 3100 to 3500 cm(-1). From the pump dependence of the vibrational relaxation the homogeneous linewidth of the amorphous ice is determined (55+/-5 cm(-1)).

  11. Active Vibration Damping of Solar Arrays

    NASA Astrophysics Data System (ADS)

    Reinicke, Gunar; Baier, Horst; Grillebeck, Anton; Scharfeld, Frank; Hunger, Joseph; Abou-El-Ela, A.; Lohberg, Andreas

    2012-07-01

    Current generations of large solar array panels are lightweight and flexible constructions to reduce net masses. They undergo strong vibrations during launch. The active vibration damping is one convenient option to reduce vibration responses and limit stresses in facesheets. In this study, two actuator concepts are used for vibration damping. A stack interface actuator replaces a panel hold down and is decoupled from bending moments and shear forces. Piezoelectric patch actuators are used as an alternative, where the number, position and size of actuators are mainly driven by controllability analyses. Linear Quadratic Gaussian control is used to attenuate vibrations of selected mode shapes with both actuators. Simulations as well as modal and acoustic tests show the feasibility of selected actuator concepts.

  12. Mechanism of bubble detachment from vibrating walls

    SciTech Connect

    Kim, Dongjun; Park, Jun Kwon Kang, Kwan Hyoung; Kang, In Seok

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  13. Microgravity Vibration Control and Civil Applications

    NASA Technical Reports Server (NTRS)

    Whorton, Mark Stephen; Alhorn, Dean Carl

    1998-01-01

    Controlling vibration of structures is essential for both space structures as well as terrestrial structures. Due to the ambient acceleration levels anticipated for the International Space Station, active vibration isolation is required to provide a quiescent acceleration environment for many science experiments. An overview is given of systems developed and flight tested in orbit for microgravity vibration isolation. Technology developed for vibration control of flexible space structures may also be applied to control of terrestrial structures such as buildings and bridges subject to wind loading or earthquake excitation. Recent developments in modern robust control for flexible space structures are shown to provide good structural vibration control while maintaining robustness to model uncertainties. Results of a mixed H-2/H-infinity control design are provided for a benchmark problem in structural control for earthquake resistant buildings.

  14. Biomolecular Imaging with Coherent Nonlinear Vibrational Microscopy

    PubMed Central

    Chung, Chao-Yu; Boik, John; Potma, Eric O.

    2014-01-01

    Optical imaging with spectroscopic vibrational contrast is a label-free solution for visualizing, identifying, and quantifying a wide range of biomolecular compounds in biological materials. Both linear and nonlinear vibrational microscopy techniques derive their imaging contrast from infrared active or Raman allowed molecular transitions, which provide a rich palette for interrogating chemical and structural details of the sample. Yet nonlinear optical methods, which include both second-order sum-frequency generation (SFG) and third-order coherent Raman scattering (CRS) techniques, offer several improved imaging capabilities over their linear precursors. Nonlinear vibrational microscopy features unprecedented vibrational imaging speeds, provides strategies for higher spatial resolution, and gives access to additional molecular parameters. These advances have turned vibrational microscopy into a premier tool for chemically dissecting live cells and tissues. This review discusses the molecular contrast of SFG and CRS microscopy and highlights several of the advanced imaging capabilities that have impacted biological and biomedical research. PMID:23245525

  15. Passively damped vibration welding system and method

    SciTech Connect

    Tan, Chin-An; Kang, Bongsu; Cai, Wayne W.; Wu, Tao

    2013-04-02

    A vibration welding system includes a controller, welding horn, an anvil, and a passive damping mechanism (PDM). The controller generates an input signal having a calibrated frequency. The horn vibrates in a desirable first direction at the calibrated frequency in response to the input signal to form a weld in a work piece. The PDM is positioned with respect to the system, and substantially damps or attenuates vibration in an undesirable second direction. A method includes connecting the PDM having calibrated properties and a natural frequency to an anvil of an ultrasonic welding system. Then, an input signal is generated using a weld controller. The method includes vibrating a welding horn in a desirable direction in response to the input signal, and passively damping vibration in an undesirable direction using the PDM.

  16. Vibrating Transducers for Fluid Measurement.

    NASA Astrophysics Data System (ADS)

    Surtees, Anthony J.

    When a structure vibrates in a fluid, some of this is carried with it creating inertial loading whilst compression adds a stiffness effect. In addition there is energy dissipation arising from viscous losses and acoustic radiation. By design, any one of these properties can be arranged to predominate. A tuning fork transducer with flat rectangular tines, is discussed. In this, a narrow laminar of gas is pumped in and out as the tines vibrate. The increase in kinetic energy contributed by this high velocity gas, gives the device a large sensitivity as a density transducer. The resonator is incorporated as the frequency controlling element in a high stability oscillator. Small piezoelectric elements are used to excite and pick-up the vibrations. A typical stability equivalent to a pressure change of 0.05 mBar, is achieved. Temperature effects are given careful analysis. A circular tuning fork, where the tines produce a radial gas displacement, is also reviewed. Common to all, is the linearity of frequency ^2 with the inverse of density for pressures above 50 mBar; a departure from linearity below this pressure (acoustic in origin); and below 10 mBar, an overriding stiffness effect where the frequency paradoxically increases with pressure. A further design comprises a resonator in which the gas is confined to two cylindrical cavities above and below a thin circular diaphragm, clamped at the periphery. In the fundamental mode, the alternating change in cavity volume exerts a stiffness, while in the first overtone, the predominantly lateral motion of the gas across the cavity adds inertia. Frequency^2 is linear with pressure for the fundamental, while for the first overtone it is inversely linear with density. A theory which is sufficiently accurate for general design purposes is presented. A sensitive viscometer is also discussed where a long rod is excited into a torsional mode with two securing nodes a quarter wavelength from either end. Driving the rod with a burst

  17. Energy scavenging from environmental vibration.

    SciTech Connect

    Galchev, Tzeno; Apblett, Christopher Alan; Najafi, Khalil

    2009-10-01

    The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The

  18. Hydrogen local vibrational modes in semiconductors

    SciTech Connect

    McCluskey, M D

    1997-06-01

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  19. Vibrational lifetimes of protein amide modes

    SciTech Connect

    Peterson, K.A.; Rella, C.A.

    1995-12-31

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid.

  20. DOSE-RESPONSE Relationships Between Whole-Body Vibration and Lumbar Disk DISEASE—A Field Study on 388 Drivers of Different Vehicles

    NASA Astrophysics Data System (ADS)

    Schwarze, S.; Notbohm, G.; Dupuis, H.; Hartung, E.

    1998-08-01

    In a longitudinal study, the dose-response relationships between long term occupational exposure to whole-body vibration and degenerative processes in the lumbar spine caused by the lumbar disks were examined. From 1990 to 1992, 388 vibration-exposed workers from different driving jobs were examined medically and by lumbar X-ray. For each individual, a history of all exposure conditions was recorded, and a cumulative vibration dose was calculated allowing comparisons between groups of low, middle, and high intensity of exposure. 310 subjects were selected for a follow-up four years later, of whom 90·6% (n=281) agreed to participate. In comparing the exposure groups, the results indicate that the limit value ofazw(8h)=0·8 m/s2should be reviewed. The best fit between the lifelong vibration dose and the occurrence of a lumbar syndrome was obtained by applying a daily reference ofazw(8h)=0·6 ms2as a limit value. The results became more distinct still when only those subjects were included in the statistical analysis who had had no lumbar symptoms up to the end of the first year of exposure. The prevalence of lumbar syndrome is 1·55 times higher in the highly exposed group when compared to the reference group with low exposure (CI95%=1·24/1·95). Calculating the cumulative incidence of new cases of lumbar syndrome in the follow-up period yields a relative risk ofRRMH=1·37 (CI95%=0·86/2·17) for the highly exposed group. It is concluded that the limit value for the calculation of an individual lifelong vibration dose should be based on a daily reference exposure ofazw(8h)=0·6 m/s2. With increasing dose it is more and more probable that cases of lumbar syndrome are caused by exposure to vibration.

  1. Variational study on the vibrational level structure and IVR behavior of highly vibrationally excited S0 formaldehyde.

    PubMed

    Rashev, Svetoslav; Moule, David C

    2012-02-15

    We perform large scale converged variational vibrational calculations on S(0) formaldehyde up to very high excess vibrational energies (E(v)), E(v)∼17,000cm(-1), using our vibrational method, consisting of a specific search/selection/Lanczos iteration procedure. Using the same method we investigate the vibrational level structure and intramolecular vibrational redistribution (IVR) characteristics for various vibrational levels in this energy range in order to assess the onset of IVR. PMID:22185953

  2. Vibration analysis methods for piping

    NASA Astrophysics Data System (ADS)

    Gibert, R. J.

    1981-09-01

    Attention is given to flow vibrations in pipe flow induced by singularity points in the piping system. The types of pressure fluctuations induced by flow singularities are examined, including the intense wideband fluctuations immediately downstream of the singularity and the acoustic fluctuations encountered in the remainder of the circuit, and a theory of noise generation by unsteady flow in internal acoustics is developed. The response of the piping systems to the pressure fluctuations thus generated is considered, and the calculation of the modal characteristics of piping containing a dense fluid in order to obtain the system transfer function is discussed. The TEDEL program, which calculates the vibratory response of a structure composed of straight and curved pipes with variable mechanical characteristics forming a three-dimensional network by a finite element method, is then presented, and calculations of fluid-structural coupling in tubular networks are illustrated.

  3. Infrared vibrational nanocrystallography and nanoimaging

    PubMed Central

    Muller, Eric A.; Pollard, Benjamin; Bechtel, Hans A.; van Blerkom, Peter; Raschke, Markus B.

    2016-01-01

    Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids. PMID:27730212

  4. Granular metamaterials for vibration mitigation

    NASA Astrophysics Data System (ADS)

    Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

    2013-09-01

    Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

  5. Vibration-Induced Droplet Atomization

    NASA Technical Reports Server (NTRS)

    Smith, M. K.; James, A.; Vukasinovic, B.; Glezer, A.

    1999-01-01

    Thermal management is critical to a number of technologies used in a microgravity environment and in Earth-based systems. Examples include electronic cooling, power generation systems, metal forming and extrusion, and HVAC (heating, venting, and air conditioning) systems. One technique that can deliver the large heat fluxes required for many of these technologies is two-phase heat transfer. This type of heat transfer is seen in the boiling or evaporation of a liquid and in the condensation of a vapor. Such processes provide very large heat fluxes with small temperature differences. Our research program is directed toward the development of a new, two-phase heat transfer cell for use in a microgravity environment. In this paper, we consider the main technology used in this cell, a novel technique for the atomization of a liquid called vibration-induced droplet atomization. In this process, a small liquid droplet is placed on a thin metal diaphragm that is made to vibrate by an attached piezoelectric transducer. The vibration induces capillary waves on the free surface of the droplet that grow in amplitude and then begin to eject small secondary droplets from the wave crests. In some situations, this ejection process develops so rapidly that the entire droplet seems to burst into a small cloud of atomized droplets that move away from the diaphragm at speeds of up to 50 cm/s. By incorporating this process into a heat transfer cell, the active atomization and transport of the small liquid droplets could provide a large heat flux capability for the device. Experimental results are presented that document the behavior of the diaphragm and the droplet during the course of a typical bursting event. In addition, a simple mathematical model is presented that qualitatively reproduces all of the essential features we have seen in a burst event. From these two investigations, we have shown that delayed droplet bursting results when the system passes through a resonance

  6. Reduced vibration motor winding arrangement

    DOEpatents

    Slavik, C.J.; Rhudy, R.G.; Bushman, R.E.

    1997-11-11

    An individual phase winding arrangement having a sixty electrical degree phase belt width for use with a three phase motor armature includes a delta connected phase winding portion and a wye connected phase winding portion. Both the delta and wye connected phase winding portions have a thirty electrical degree phase belt width. The delta and wye connected phase winding portions are each formed from a preselected number of individual coils each formed, in turn, from an unequal number of electrical conductor turns in the approximate ratio of {radical}3. The individual coils of the delta and wye connected phase winding portions may either be connected in series or parallel. This arrangement provides an armature winding for a three phase motor which retains the benefits of the widely known and utilized thirty degree phase belt concept, including improved mmf waveform and fundamental distribution factor, with consequent reduced vibrations and improved efficiency. 4 figs.

  7. Reduced vibration motor winding arrangement

    DOEpatents

    Slavik, Charles J.; Rhudy, Ralph G.; Bushman, Ralph E.

    1997-01-01

    An individual phase winding arrangement having a sixty electrical degree phase belt width for use with a three phase motor armature includes a delta connected phase winding portion and a wye connected phase winding portion. Both the delta and wye connected phase winding portions have a thirty electrical degree phase belt width. The delta and wye connected phase winding portions are each formed from a preselected number of individual coils each formed, in turn, from an unequal number of electrical conductor turns in the approximate ratio of .sqroot.3. The individual coils of the delta and wye connected phase winding portions may either be connected in series or parallel. This arrangement provides an armature winding for a three phase motor which retains the benefits of the widely known and utilized thirty degree phase belt concept, including improved mmf waveform and fundamental distribution factor, with consequent reduced vibrations and improved efficiency.

  8. Particle manipulation using vibrating cilia

    NASA Astrophysics Data System (ADS)

    Tallapragada, Phanindra; Kelly, Scott

    2012-11-01

    The ability to manipulate small particles suspended in fluids has many practical applications, ranging from the mechanical testing of macromolecules like DNA to the controlled abrasion of brittle surfaces for precision polishing. A natural method is non-contact manipulation of particles through boundary excitations. Particle-manipulation via a vibrating cilia to establish controlled fluid flows with desired patterns of transport is one such bioinspired method. We show experimental results on the clustering and transport of finite-sized particles in the streaming flow set up by the oscillating cilia. We further show computations to explain the effects of hyperbolic structures in the four dimensional phase space of the dynamics of finite-sized particles.

  9. High performance rotational vibration isolator.

    PubMed

    Sunderland, Andrew; Blair, David G; Ju, Li; Golden, Howard; Torres, Francis; Chen, Xu; Lockwood, Ray; Wolfgram, Peter

    2013-10-01

    We present a new rotational vibration isolator with an extremely low resonant frequency of 0.055 ± 0.002 Hz. The isolator consists of two concentric spheres separated by a layer of water and joined by very soft silicone springs. The isolator reduces rotation noise at all frequencies above its resonance which is very important for airborne mineral detection. We show that more than 40 dB of isolation is achieved in a helicopter survey for rotations at frequencies between 2 Hz and 20 Hz. Issues affecting performance such as translation to rotation coupling and temperature are discussed. The isolator contains almost no metal, making it particularly suitable for electromagnetic sensors.

  10. Downhole Vibration Monitoring & Control System

    SciTech Connect

    Martin E. Cobern

    2007-03-31

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II were: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in a drilling laboratory. Phase II concluded on January 31, 2006, and the Phase II final report was issued. Work on Phase III of the project began during the first quarter, 2006. Efforts the current quarter have continued to focus on the manufacture of the prototype and precommercial parts, field test planning and commercialization. The continued extreme lead times quoted by oilfield machine shops for collar components significantly delayed the deployment of the prototype and precommercial units. All parts have now been received for two units, and all but one for the third. Mechanical assembly of the first two systems is complete and the electronics installation and laboratory testing will be finished in April. We have entered into a Memorandum of Understanding with a major US oilfield equipment supplier, which calls for their assisting with our field tests, in cash and in kind. We are close to signing a definitive agreement which includes the purchase of the three precommercial units. We had also signed a CRADA with the Rocky Mountain Oilfield Test Center (RMOTC), and scheduled a test at their site, The RMOTC drilling schedule continues to slip, and the test cannot begin until the first week of May. Based on these factors, we have requested a no-cost extension to July 31, 2007.

  11. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2006-05-01

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II were: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Phase II concluded on January 31, 2006. The month of January was devoted to the final preparations for, and conducting of testing of the DVMCS at TerraTek laboratories in Salt Lake City. This testing was concluded on January 27, 2006. Much of the effort in this period was then devoted to the analysis of the data and the preparation of the Phase II final report. The report was issued after the close of the period. Work on Phase III of the project began during this quarter. It has consisted of making some modifications in the prototype design to make it more suitable for field testing an more practical for commercial use. This work is continuing. The redesign effort, coupled with the current extreme lead times quoted by oilfield machine shops for collar components, will delay the deployment of the field prototypes. The precommercial prototypes are being developed in parallel, so the project should be completed per the current schedule.

  12. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2005-04-27

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. As a result of the lower than expected performance of the MR damper noted last quarter, several additional tests were conducted. These dealt with possible causes of the lack of dynamic range observed in the testing: additional damping from the oil in the Belleville springs; changes in properties of the MR fluid; and, residual magnetization of the valve components. Of these, only the last was found to be significant. By using a laboratory demagnetization apparatus between runs, a dynamic range of 10:1 was achieved for the damper, more than adequate to produce the needed improvements in drilling. Additional modeling was also performed to identify a method of increasing the magnetic field in the damper. As a result of the above, several changes were made in the design. Additional circuitry was added to demagnetize the valve as the field is lowered. The valve was located to above the Belleville springs to reduce the load placed upon it and offer a greater range of materials for its construction. In addition, to further increase the field strength, the coils were relocated from the mandrel to the outer housing. At the end of the quarter, the redesign was complete and new parts were on order. The project is approximately three months behind schedule at this time.

  13. a Decade of Improvement in Whole-Body Vibration and Low Back Pain for Freight Container Tractor Drivers

    NASA Astrophysics Data System (ADS)

    Nishiyama, K.; Taoda, K.; Kitahara, T.

    1998-08-01

    The authors' study in 1983 revealed that the whole-body vibration of the tractor units of freight containers was most hazardous in the back-to-chest directions (x-axis). The allowable exposure time was considerably shorter than that for heavy duty trucks. The low back pain (LBP) among the drivers seemed to be due to the long working hours and the ergonomically unsound tractor design, as well as the vibration. A preventative measure was the introduction of a tractor cab suspended by an air spring instead of a steel spring. In 1992, a follow-up field study was conducted. A personal vibration exposure meter developed by us measured the whole-body vibration on eight tractors. Eighty-nine triplets matched with the age and the years of driving tractors answered a questionnaire evaluation of the ergonomics of their tractor units.The comparison of the newest steel suspension vehicles to the old ones produced by the same motor company revealed that in thex-axis the vibration level had decreased by as much as 4 to 9 dB. Some tractors showed an increase in vibration in the buttocks-to-head direction (z-axis). However, such adverse changes seemed not to affect evaluations according to the fatigue-decreased proficiency boundary (FDP) and the exposure limit (EL) recommended in ISO 2631-1978. The present models, regardless of the type of suspension, changed the direction of the most hazardous vibration from thex-axis to thez-axis. However, the effect of the air-suspension was not so remarkable as expected. Among 40% of drivers seemed to exceed the FDP boundary during a day.The questionnaire study showed an improvement in the ergonomic evaluation of the tractors. The air suspension models seemed to induce less LBP than the steel suspension models.

  14. The Effects of Random Vibration on the Dimensional Stability of Precision Structures

    NASA Astrophysics Data System (ADS)

    Edeson, Ruben L.; Aglietti, Guglielmo S.; Tatnall, Adrian R.

    2012-07-01

    Precision structures for space-based optical systems are typically subjected to brief periods of random vibration during the launch and ground testing phases. Such events pose a potential threat to the dimensional stability of such structures, which may be required to maintain positional tolerances on large optics in the low 10s of microns to meet optical performance requirements. Whilst there is an abundance of information in the literature on structural instability caused by hygrothermal cycling, there appears to have been little work done on the effects of random vibration. This issue has recently been addressed at RAL with a series of tests aimed at characterizing the behavior of dimensional instability in structures for high-resolution Earth-imaging cameras subject to random vibration. Firstly, a breadboard model of a typical “conventional” CFRP-based optical payload structure was produced and subjected to a range of environmental tests. The effects of random vibration were compared to those of other environmental stressors (such as thermal vacuum testing) and found to be significant. Next, controlled tests were performed on specific structural areas in order to assess the specific contributions of each area to overall instability. These tests made use of novel test setups and metrology techniques to assess the dimensional stability response of material samples and bolted joints to random vibration exposure. The tests were able to measure dimensional instability, characterize it over a series of tests of increasing vibration levels, and assess variability in results between identical samples. Finally, a predictive technique using a Finite Element Model with nonlinear kinematic hardening was produced. A time domain solution was obtained, using an analogy to Miner’s Rule to determine load cycle amplitudes. This model correlated reasonably well with test results. This paper presents this program of work, and the results. It also proposes ways to minimize

  15. Whole-body vibration induces pain and lumbar spinal inflammation responses in the rat that vary with the vibration profile.

    PubMed

    Zeeman, Martha E; Kartha, Sonia; Winkelstein, Beth A

    2016-08-01

    Whole-body vibration (WBV) is linked epidemiologically to neck and back pain in humans, and to forepaw mechanical allodynia and cervical neuroinflammation in a rodent model of WBV, but the response of the low back and lumbar spine to WBV is unknown. A rat model of WBV was used to determine the effect of different WBV exposures on hind paw behavioral sensitivity and neuroinflammation in the lumbar spinal cord. Rats were exposed to 30 min of WBV at either 8 or 15 Hz on days 0 and 7, with the lumbar spinal cord assayed using immunohistochemistry at day 14. Behavioral sensitivity was measured using mechanical stimulation of the hind paws to determine the onset, persistence, and/or recovery of allodynia. Both WBV exposures induce mechanical allodynia 1 day following WBV, but only the 8 Hz WBV induces a sustained decrease in the withdrawal threshold through day 14. Similarly, increased activation of microglia, macrophages, and astrocytes in the superficial dorsal horn of the lumbar spinal cord is only evident after the painful 8 Hz WBV. Moreover, extracellular signal-regulated kinase (ERK)-phosphorylation is most robust in neurons and astrocytes of the dorsal horn, with the most ERK phosphorylation occurring in the 8 Hz group. These findings indicate that a WBV exposure that induces persistent pain also induces a host of neuroimmune cellular activation responses that are also sustained. This work indicates there is an injury-dependent response that is based on the vibration parameters, providing a potentially useful platform for studying mechanisms of painful spinal injuries. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1439-1446, 2016.

  16. Whole-body vibration induces pain and lumbar spinal inflammation responses in the rat that vary with the vibration profile.

    PubMed

    Zeeman, Martha E; Kartha, Sonia; Winkelstein, Beth A

    2016-08-01

    Whole-body vibration (WBV) is linked epidemiologically to neck and back pain in humans, and to forepaw mechanical allodynia and cervical neuroinflammation in a rodent model of WBV, but the response of the low back and lumbar spine to WBV is unknown. A rat model of WBV was used to determine the effect of different WBV exposures on hind paw behavioral sensitivity and neuroinflammation in the lumbar spinal cord. Rats were exposed to 30 min of WBV at either 8 or 15 Hz on days 0 and 7, with the lumbar spinal cord assayed using immunohistochemistry at day 14. Behavioral sensitivity was measured using mechanical stimulation of the hind paws to determine the onset, persistence, and/or recovery of allodynia. Both WBV exposures induce mechanical allodynia 1 day following WBV, but only the 8 Hz WBV induces a sustained decrease in the withdrawal threshold through day 14. Similarly, increased activation of microglia, macrophages, and astrocytes in the superficial dorsal horn of the lumbar spinal cord is only evident after the painful 8 Hz WBV. Moreover, extracellular signal-regulated kinase (ERK)-phosphorylation is most robust in neurons and astrocytes of the dorsal horn, with the most ERK phosphorylation occurring in the 8 Hz group. These findings indicate that a WBV exposure that induces persistent pain also induces a host of neuroimmune cellular activation responses that are also sustained. This work indicates there is an injury-dependent response that is based on the vibration parameters, providing a potentially useful platform for studying mechanisms of painful spinal injuries. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1439-1446, 2016. PMID:27571442

  17. Survey of Technical Preventative Measures to Reduce Whole-Body Vibration Effects when Designing Mobile Machinery

    NASA Astrophysics Data System (ADS)

    DONATI, P.

    2002-05-01

    Engineering solutions to minimize the effects on operators of vibrating mobile machinery can be conveniently grouped into three areas: Reduction of vibration at source by improvement of the quality of terrain, careful selection of vehicle or machine, correct loading, proper maintenance, etc.Reduction of vibration transmission by incorporating suspension systems (tyres, vehicle suspensions, suspension cab and seat) between the operator and the source of vibration.Improvement of cab ergonomics and seat profiles to optimize operator posture. These paper reviews the different techniques and problems linked to categories (2) and (3). According to epidemiological studies, the main health risk with whole-body vibration exposure would appear to be lower back pain. When designing new mobile machinery, all factors which may contribute to back injury should be considered in order to reduce risk. For example, optimized seat suspension is useless if the suspension seat cannot be correctly and easily adjusted to the driver's weight or if the driver is forced to drive in a bent position to avoid his head striking the ceiling due to the spatial requirement of the suspension seat.

  18. Whole-body vibration training induces hypertrophy of the human patellar tendon.

    PubMed

    Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

    2016-08-01

    Animal studies suggest that regular exposure to whole-body vibration (WBV) induces an anabolic response in bone and tendon. However, the effects of this type of intervention on human tendon properties and its influence on the muscle-tendon unit function have never been investigated. The aim of this study was to investigate the effect of WBV training on the patellar tendon mechanical, material and morphological properties, the quadriceps muscle architecture and the knee extension torque-angle relationship. Fifty-five subjects were randomized into either a vibration, an active control, or an inactive control group. The active control subjects performed isometric squats on a vibration platform without vibration. Muscle and tendon properties were measured using ultrasonography and dynamometry. Vibration training induced an increase in proximal (6.3%) and mean (3.8%) tendon cross-sectional area, without any appreciable change in tendon stiffness and modulus or in muscle architectural parameters. Isometric torque at a knee angle of 90° increased in active controls (6.7%) only and the torque-angle relation remained globally unchanged in all groups. The present protocol did not appreciably alter knee extension torque production or the musculo-tendinous parameters underpinning this function. Nonetheless, this study shows for the first time that WBV elicits tendon hypertrophy in humans. PMID:26173589

  19. Measurement of small mechanical vibrations of brain tissue exposed to extremely-low-frequency electric fields

    SciTech Connect

    Spiegel, R.J.; Ali, J.S.; Peoples, J.F.; Joines, W.T.

    1986-01-01

    Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely-low-frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposure cell is a section of X-band waveguide that was modified by the addition of a center conductor to form a small TEM cell within the waveguide structure. The ELF signal is applied to the center conductor of the TEM cell. The applied ELF electric field generates an electrostrictive force on the surface of the brain tissue. This force causes the tissue to vibrate at a frequency equal to twice the frequency of the applied sinusoidal signal. An X-band signal is fed through the waveguide, scattered by the vibrating sample, and detected by a phrase-sensitive receiver. Using a time-averaging spectrum analyzer, a vibration sensitivity of approximately 0.2 nmpp can be achieved. The amplitude of the brain tissue vibrational frequencies below 50 Hz; between 50 and 200 Hz resonant phenomena were observed; and above 200 Hz the amplitude fall-off is rapid.

  20. Short term response of insulin, glucose, growth hormone and corticosterone to acute vibration in rats.

    NASA Technical Reports Server (NTRS)

    Dolkas, C. B.; Leon, H. A.; Chackerian, M.

    1971-01-01

    Study carried out to obtain some notion of the initial phasing and interactive effects among some hormones known to be responsive to vibration stress. Sprague-Dawley derived rats were exposed to the acute effects of confinement and confinement with lateral (plus or minus G sub y) vibration. The coincident monitoring of glucose, insulin, growth hormone, and corticosterone plasma levels, during and immediately subsequent to exposure to brief low level vibration, exhibits the effects of inhibition of insulin release by epinephrine. The ability of insulin (IRI) to return rapidly to basal levels, from appreciably depressed levels during vibration, in the face of elevated levels of glucose is also shown. Corticosterone responds with almost equal rapidity, but in opposite phase to the IRI. The immuno-assayable growth hormone (IGH) dropped from a basal level of 32 ng/ml to 7.3 ng/ml immediately subsequent to vibration and remained at essentially that level throughout the experiment (60 min). Whether these levels represent a real fall in the rat or whether they merely follow the immuno-logically deficient form is still in question.

  1. The kinetics of post-vibration tension recovery of the isolated rat portal vein.

    PubMed

    Klemt, P; Peiper, U; Speden, R N; Zilker, F

    1981-03-01

    1. The kinetics of post-vibration tension recovery have been examined during electrical, noradrenaline or KCl stimulation of the isolated rat portal vein. 2. Inhibition of isometric contractions produced by a combination of noradrenaline (20 microM) and KCl (53 mM) by longitudinal, 100 Hz sinusoidal vibration increased with increasing vibration amplitude up to a maximum of 78.7% of the active tension. This inhibition was little affected by a decrease in temperature from 37 to 25 degrees C. Recovery of tension after the end of vibration was complete and took place exponentially. The time constant for this recovery was little affected by changes in vibration amplitude, but increased from 1.72 +/- 0.09 to 4.35 +/- 0.33 sec, for large amplitude vibrations, when the temperature was lowered from 37 to 25 degrees C. 3. The increase in isometric tension during 50 Hz a.c. electrical field stimulation was exponential, apart from a minor initial activation component, and took place with a time constant of 1.25 +/- 0.17 sec. Neither delaying nor interrupting development of this contraction with inhibitory vibration altered the time constant for this exponential increase in tension. There was no correlation between the time constant and the maximum active tension achieved after vibration was stopped. 4. Post-vibration tension recovery during electrical, noradrenaline (20 microM) or KCl (120-130 mM) stimulation was independent of the nature of the stimulus at comparable times of stimulation, but the time constant increased during exposures of more than 10 sec to either noradrenaline or KCl. With noradrenaline, the increase was from 1.45 +/- 0.10 sec after 50 sec of stimulation to 2.24 +/- 0.16 sec after 336 sec of stimulation (P less than 0.0005). Such an increase in the time constant may reflect slower cycling of cross-bridges with an improvement in the efficiency by which contraction is maintained. 5. The kinetics of post-vibration tension recovery were those of a

  2. Simulation studies for multichannel active vibration control

    NASA Astrophysics Data System (ADS)

    Prakash, Shashikala; Balasubramaniam, R.; Praseetha, K. K.

    2003-10-01

    Traditional approach to vibration control uses passive techniques, which are relatively large, costly and ineffective at low frequencies. Active Vibration Control (AVC) is used to overcome these problems & in AVC additional sources (secondary) are used to cancel vibration from primary source based on the principle of superposition theorem Since the characteristics of the vibration source and environment are time varying, the AVC system must be adaptive. Adaptive systems have the ability to track time varying disturbances and provide optimal control over a much broader range of conditions than conventional fixed control systems. In multi channel AVC vibration fields in large dimensions are controlled & is more complicated. Therefore to actively control low frequency vibrations on large structures, multi channel AVC requires a control system that uses multiple secondary sources to control the vibration field simultaneously at multiple error sensor locations. The error criterion that can be directly measured is the sum of squares of outputs of number of sensors. The adaptive algorithm is designed to minimize this & the algorithm implemented is the "Multiple error LMS algorithm." The best known applications of multiple channel FXLMS algorithm is in real time AVC and system identification. More wider applications are in the control of propeller induced noise in flight cabin interiors. In the present paper the results of simulation studies carried out in MATLAB as well as on TMS320C32 DSP processor will be brought out for a two-channel case.

  3. Local metabolic rate during whole body vibration.

    PubMed

    Friesenbichler, Bernd; Nigg, Benno M; Dunn, Jeff F

    2013-05-15

    Whole body vibration (WBV) platforms are currently used for muscle training and rehabilitation. However, the effectiveness of WBV training remains elusive, since scientific studies vary largely in the vibration parameters used. The origin of this issue may be related to a lack in understanding of the training intensity that is imposed on individual muscles by WBV. Therefore, this study evaluates the training intensity in terms of metabolic rate of two lower-extremity muscles during WBV under different vibration parameters. Fourteen healthy male subjects were randomly exposed to 0 (control)-, 10-, 17-, and 28-Hz vibrations while standing upright on a vibration platform. A near-infrared spectrometer was used to determine the gastrocnemius medialis (GM) and vastus lateralis (VL) muscles' metabolic rates during arterial occlusion. The metabolic rates during each vibration condition were significantly higher compared with control for both muscles (P < 0.05). Each increase in vibration frequency translated into a significantly higher metabolic rate than the previous lower frequency (P < 0.05) for both muscles. The current study showed that the local metabolic rate during WBV at 28 Hz was on average 5.4 times (GM) and 3.7 times (VL) of the control metabolic rate. The substantial changes in local metabolic rate indicate that WBV may represent a significant local training stimulus for particular leg muscles.

  4. Vibration energy harvester optimization using artificial intelligence

    NASA Astrophysics Data System (ADS)

    Hadas, Z.; Ondrusek, C.; Kurfurst, J.; Singule, V.

    2011-06-01

    This paper deals with an optimization study of a vibration energy harvester. This harvester can be used as autonomous source of electrical energy for remote or wireless applications, which are placed in environment excited by ambient mechanical vibrations. The ambient energy of vibrations is usually on very low level but the harvester can be used as alternative source of energy for electronic devices with an expected low level of power consumption of several mW. The optimized design of the vibration energy harvester was based on previous development and the sensitivity of harvester design was improved for effective harvesting from mechanical vibrations in aeronautic applications. The vibration energy harvester is a mechatronic system which generates electrical energy from ambient vibrations due to precision tuning up generator parameters. The optimization study for maximization of harvested power or minimization of volume and weight are the main goals of our development. The optimization study of such complex device is complicated therefore artificial intelligence methods can be used for tuning up optimal harvester parameters.

  5. Active damping of spacecraft structural appendage vibrations

    NASA Technical Reports Server (NTRS)

    Fedor, Joseph V. (Inventor)

    1990-01-01

    An active vibration damper system, for bending in two orthogonal directions and torsion, in each of three mutually perpendicular axes is located at the extremities of the flexible appendages of a space platform. The system components for each axis includes: an accelerometer, filtering and signal processing apparatus, and a DC motor-inertia wheel torquer. The motor torquer, when driven by a voltage proportional to the relative vibration tip velocity, produces a reaction torque for opposing and therefore damping a specific modal velocity of vibration. The relative tip velocity is obtained by integrating the difference between the signal output from the accelerometer located at the end of the appendage with the output of a usually carried accelerometer located on a relatively rigid body portion of the space platform. A selector switch, with sequential stepping logic or highest modal vibration energy logic, steps to another modal tip velocity channel and receives a signal voltage to damp another vibration mode. In this manner, several vibration modes can be damped with a single sensor/actuator pair. When a three axis damper is located on each of the major appendages of the platform, then all of the system vibration modes can be effectively damped.

  6. Influence of low-frequency vibration on changes of biochemical parameters of living rats

    NASA Astrophysics Data System (ADS)

    Kasprzak, Cezary; Damijan, Zbigniew; Panuszka, Ryszard

    2001-05-01

    The aim of the research was to investigate how some selected biochemical parameters of living rats depend on exposure of low-frequency vibrations. Experiments were run on 30 Wistar rats randomly segregated into three groups: (I) 20 days old (before puberty), (II) 70th day after; (III) control group. The exposure was repeated seven times, for 3 h, at the same time of day. Vibrations applied during the first tests of the experiment had acceleration 1.22 m/s2 and frequency 20 Hz. At the 135th day the rats' bones were a subject of morphometric/biochemical examination. The results of biochemical tests proved decrease in LDL and HDL cholesterol levels for exposed rats as well as the Ca contents in blood plasma. There was evident increasing of Ca in blood plasma in exposed rats for frequency of exposition.

  7. Optimizing Vibrational Coordinates To Modulate Intermode Coupling.

    PubMed

    Zimmerman, Paul M; Smereka, Peter

    2016-04-12

    The choice of coordinate system strongly affects the convergence properties of vibrational structure computations. Two methods for efficient generation of improved vibrational coordinates are presented and justified by analysis of a model anharmonic two-mode Hessian and numerical computations on polyatomic molecules. To produce optimal coordinates, metrics which quantify off-diagonal couplings over a grid of Hessian matrices are minimized through unitary rotations of the vibrational basis. The first proposed metric minimizes the total squared off-diagonal coupling, and the second minimizes the total squared change in off-diagonal coupling. In this procedure certain anharmonic modes tend to localize, for example X-H stretches. The proposed methods do not rely on prior fitting of the potential energy, vibrational structure computations, or localization metrics, so they are unique from previous vibrational coordinate generation algorithms and are generally applicable to polyatomic molecules. Fitting the potential to the approximate n-mode representation in the optimized bases for all-trans polyenes shows that off-diagonal anharmonic couplings are substantially reduced by the new choices of coordinate system. Convergence of vibrational energies is examined in detail for ethylene, and it is shown that coupling-optimized modes converge in vibrational configuration interaction computations to within 1 cm(-1) using only 3-mode couplings, where normal modes require 4-mode couplings for convergence. Comparison of the vibrational configuration interaction convergence with respect to excitation level for the two proposed metrics shows that minimization of the total off-diagonal coupling is most effective for low-cost vibrational structure computations.

  8. Low cost subpixel method for vibration measurement

    NASA Astrophysics Data System (ADS)

    Ferrer, Belen; Espinosa, Julian; Roig, Ana B.; Perez, Jorge; Acevedo, Pablo; Mas, David

    2014-05-01

    Traditional vibration measurement methods are based on devices that acquire local data by direct contact (accelerometers, GPS) or by laser beams (Doppler vibrometers). Our proposal uses video processing to obtain the vibration frequency directly from the scene, without the need of auxiliary targets or devices. Our video-vibrometer can obtain the vibration frequency at any point in the scene and can be implemented with low-cost devices, such as commercial cameras. Here we present the underlying theory and some experiments that support our technique.

  9. Low cost subpixel method for vibration measurement

    SciTech Connect

    Ferrer, Belen; Espinosa, Julian; Perez, Jorge; Acevedo, Pablo; Mas, David; Roig, Ana B.

    2014-05-27

    Traditional vibration measurement methods are based on devices that acquire local data by direct contact (accelerometers, GPS) or by laser beams (Doppler vibrometers). Our proposal uses video processing to obtain the vibration frequency directly from the scene, without the need of auxiliary targets or devices. Our video-vibrometer can obtain the vibration frequency at any point in the scene and can be implemented with low-cost devices, such as commercial cameras. Here we present the underlying theory and some experiments that support our technique.

  10. Nonlinear vibration energy harvester using diamagnetic levitation

    NASA Astrophysics Data System (ADS)

    Liu, L.; Yuan, F. G.

    2011-05-01

    This letter proposes a nonlinear vibration energy harvester based on stabilized magnetic levitation using diamagnetic. Restoring forces induced by the magnetic field in harvesting vibration energy is employed instead of the forces introduced by conventional mechanical suspensions; therefore dissipation of vibration energy into heat through mechanical suspensions is eliminated. The core of the design consists of two spiral coils made of diamagnetic materials, which serve dual purposes: providing nonlinear restoring force and harnessing eddy current to power external circuits. From the theoretical analysis presented, the proposed harvester has the potential to provide wideband power outputs in low frequency range.

  11. CO2 compressor vibration and cause analysis

    NASA Technical Reports Server (NTRS)

    Ying, Y. L.

    1985-01-01

    The operational experience of a large turbine drive carbon dioxide compressor train in a urea plant with capacity of 1620 tons/day is considered. After the initial start-up in 1976, the vibration in the HP cylinder was comparatively serious. The radial vibration reached 4.2 to 4.5 mils and fluctuated around this value. It was attributed to the rotating stall based on the spectrum analysis. Additional return line from the 4th to 4th and higher temperature of the 4th inlet has cured the vibration. Problems are described which were encountered in the operation along with their solutions, and/or improvements.

  12. Microelectromechanical power generator and vibration sensor

    DOEpatents

    Roesler, Alexander W.; Christenson, Todd R.

    2006-11-28

    A microelectromechanical (MEM) apparatus is disclosed which can be used to generate electrical power in response to an external source of vibrations, or to sense the vibrations and generate an electrical output voltage in response thereto. The MEM apparatus utilizes a meandering electrical pickup located near a shuttle which holds a plurality of permanent magnets. Upon movement of the shuttle in response to vibrations coupled thereto, the permanent magnets move in a direction substantially parallel to the meandering electrical pickup, and this generates a voltage across the meandering electrical pickup. The MEM apparatus can be fabricated by LIGA or micromachining.

  13. Applications of Fault Detection in Vibrating Structures

    NASA Technical Reports Server (NTRS)

    Eure, Kenneth W.; Hogge, Edward; Quach, Cuong C.; Vazquez, Sixto L.; Russell, Andrew; Hill, Boyd L.

    2012-01-01

    Structural fault detection and identification remains an area of active research. Solutions to fault detection and identification may be based on subtle changes in the time series history of vibration signals originating from various sensor locations throughout the structure. The purpose of this paper is to document the application of vibration based fault detection methods applied to several structures. Overall, this paper demonstrates the utility of vibration based methods for fault detection in a controlled laboratory setting and limitations of applying the same methods to a similar structure during flight on an experimental subscale aircraft.

  14. Vibration modeling and supression in tennis racquets.

    SciTech Connect

    Farrar, C. R.; Buechler, M. A.; Espino, Luis; Thompson, G. A.

    2003-01-01

    The size of the 'sweet spot' is one measure of tennis racquet performance. In terms of vibration, the sweet spot is determined by the placement of nodal lines across the racquet head. In this studx the vibrational characteristics of a tennis racquet are explorod to discover the size and location of the sweet spot. A numerical model of the racquet is developed using finite element analysis and the model is verified using the results from an experimental modal analysis. The affects of string tension on the racquet's sweet spot and mode shapes are then quantified. An investigation is also carried out to determine how add-on vibrational datnpers affect the sweet spot.

  15. Vibrational power flow models for transversely vibrating finite Mindlin plate

    NASA Astrophysics Data System (ADS)

    Park, Young-Ho; Hong, Suk-Yoon

    2008-11-01

    In this paper, power flow models were developed to analyze transversely vibrating finite Mindlin plate considering the effects of shear distortion and rotatory inertia, which are very important at high frequencies. The energy governing equations for far-field propagating out-of-plane waves in the Mindlin plate were newly derived by using the classical displacement solutions for out-of-plane motions in the Mindlin plate. The derived energy governing equations are composed of the energetics of three kinds of far-field propagating waves. Below the critical frequency, the energy governing equation for only one kind of far-field propagating wave, which is analogous to that for flexural wave in the Kirchhoff plate, is obtained. On the other hand, above the critical frequency, the energy governing equations for all three kinds of far-field propagating waves are derived. The developed power flow models are in the general forms incorporating not only the Mindlin plate theory but also the Kirchhoff plate theory. To verify the validity and accuracy of the derived models, numerical analyses are performed for the case where the finite Mindlin plates are excited by a harmonic point force, and the spatial distributions and levels of energy density and intensity obtained by the developed power flow solutions for the Mindlin plate are compared with those obtained by the classical displacement solutions for the Mindlin plate, the traditional power flow solutions, and the classical displacement solutions for the Kirchhoff plate for various excitation frequencies and hysteretic damping factors.

  16. Exposure chamber

    DOEpatents

    Moss, Owen R.

    1980-01-01

    A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.

  17. Vibrational Cooling in A Cold Ion Trap: Vibrationally Resolved Photoelectron Spectroscopy of Cold C60- Anions

    SciTech Connect

    Wang, Xue B.; Woo, Hin-koon; Wang, Lai S.

    2005-08-01

    We demonstrate vibrational cooling of anions via collisions with a background gas in an ion trap attached to a cryogenically controlled cold head (10 ? 400 K). Photoelectron spectra of vibrationally cold C60- anions, produced by electrospray ionization and cooled in the cold ion trap, have been obtained. Relative to spectra taken at room temperature, vibrational hot bands are completely eliminated, yielding well resolved vibrational structures and a more accurate electron affinity for neutral C60. The electron affinity of C60 is measured to be 2.683 ? 0.008 eV. The cold spectra reveal complicated vibrational structures for the transition to the C60 ground state due to the Jahn-Teller effect in the ground state of C60-. Vibrational excitations in the two Ag modes and eight Hg modes are observed, providing ideal data to assess the vibronic couplings in C60-.

  18. Measurement of phthalates in skin wipes: estimating exposure from dermal absorption.

    PubMed

    Gong, Mengyan; Zhang, Yinping; Weschler, Charles J

    2014-07-01

    This study has determined the levels of six phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di(isobutyl) phthalate (DiBP), di(n-butyl) phthalate (DnBP), butyl benzyl phthalate (BBzP), and di(2-ethylhexyl) phthalate (DEHP)) in skin wipes; examined factors that might influence the levels, including body location, time of sampling, and hand-washing; and estimated dermal absorption based on the measured levels. Skin wipes were collected from the forehead, forearm, back-of-hand, and palm of 20 participants using gauze pads moistened with isopropanol. DiBP, DnBP, and DEHP were most frequently detected; DEHP levels were substantially higher than DnBP and DiBP levels, and DnBP levels were somewhat lower than DiBP levels. The levels differed at different body locations, with palm > back-of-hand > forearm ≥ forehead. Repeated wipe sampling from six participants over a 1 month period indicated that levels at the same body location did not vary significantly. The estimated median total dermal absorption from skin surface lipids on the palm, back-of-hand, arm, and head are 0.48, 0.68, and 0.66 (μg/kg)/day for DiBP, DnBP, and DEHP, respectively. These estimates are roughly 10-20% of the total uptake reported for Chinese adults and suggest that dermal absorption contributes significantly to the uptake of these phthalates. Washing with soap and water removed more than 50% of the phthalates on the hands and may be a useful tool in decreasing aggregate phthalate exposure. PMID:24911978

  19. Acute Whole-Body Vibration does not Facilitate Peak Torque and Stretch Reflex in Healthy Adults

    PubMed Central

    Yeung, Ella W.; Lau, Cheuk C.; Kwong, Ada P.K.; Sze, Yan M.; Zhang, Wei Y.; Yeung, Simon S.

    2014-01-01

    The acute effect of whole-body vibration (WBV) training may enhance muscular performance via neural potentiation of the stretch reflex. The purpose of this study was to investigate if acute WBV exposure affects the stretch induced knee jerk reflex [onset latency and electromechanical delay (EMD)] and the isokinetic knee extensor peak torque performance. Twenty-two subjects were randomly assigned to the intervention or control group. The intervention group received WBV in a semi-squat position at 30° knee flexion with an amplitude of 0.69 mm, frequency of 45 Hz, and peak acceleration of 27.6 m/s2 for 3 minutes. The control group underwent the same semii-squatting position statically without exposure of WBV. Two-way mixed repeated measures analysis of variance revealed no significant group effects differences on reflex latency of rectus femoris (RF) and vastus lateralis (VL; p = 0.934 and 0.935, respectively) EMD of RF and VL (p = 0.474 and 0.551, respectively) and peak torque production (p = 0.483) measured before and after the WBV. The results of this study indicate that a single session of WBV exposure has no potentiation effect on the stretch induced reflex and peak torque performance in healthy young adults. Key Points There is no acute potentiation of stretch reflex right after whole body vibration. Acute whole body vibration does not improve mus-cle peak torque performance in healthy young adults. PMID:24570602

  20. Vibrational Corrections to Molecular Properties: Second-Order Vibrational Perturbation Theory VS Variational Computations

    NASA Astrophysics Data System (ADS)

    Harding, Michael E.; Vázquez, Juana; Stanton, John F.; Diezemann, Gregor; Gauss, Jürgen

    2011-06-01

    For a small set of linear and non-linear molecules, a detailed comparison of two different procedures for predicting vibrationally averaged molecular properties, i.e., second-order vibrational perturbation theory (VPT2) and a variational approach, is carried out. Results for vibrational corrections to dipole and quadrupole moments, nuclear quadrupole moments, static electric-dipole polarizabilities, NMR chemical shielding tensors, nuclear spin-rotation tensors, magnetizabilities, and rotational g-tensors are reported.