Hand-transmitted vibration

Some data also suggest an increased risk of systemic sclerosis in workers exposed to hand-transmitted vibration due to the use of vibrating tools (Bovenzi et al., 2001). 

Bovenzi M, Barbone F, Pisa FE, Betta A, Romeo L (2001) Scleroderma and occupational exposure to hand-transmitted vibration. Int Arch Occup Environ Health, 74(8) 579-582. 

Frequency Weighting. The inverse frequency contour (i.e., reciprocal) to an equinoxious contour should be applied to a stimulus containing many frequencies to produce an overall magnitude that appropriately combines the contributions from each fr uency. The frequency weightings most commonly employed for whole-body and hand-transmitted vibration are shown in Fig. 10.1 (ISO 2631-1,1997 ISO 5349-1, 2001). The range of frequencies is from 1 to 80 Hz for whole-body vibration, and from 8 to 1250 Hz for vibration entering the hand. A frequency weighting for shocks may also be derived from a biodynamic model (see Dynamic Response Index (DRI) in Sec. 10.3.1). 

The measurement of hand-transmitted vibration requires a bandwidth extending to at least 1250 Hz, which is unobtainable by localized, skin-mount transducers. Attempts to strap the transducer to a bony prominence (e.g., by a watch strap at the wrist) have demonstrated that the upper frequency limit for this method of measurement is about 200 Hz (Boileau et al., 1992). A distributed sensor, such as a pressure-sensitive lightweight film, would permit the motion of a large skin area to be monitored with acceptable mass loading, and could respond to vibration at higher frequencies. 

FIGURE 10 Basicentric coordinate axes for translationai (x, y, and 2) and rotational (r and rj whole-body vibratkn, and basicentric (filled circles and dashed lines) and biodynamic (open circles and continuous lines) axes for hand-transmitted vibration. The biodynamic coo inales axes for the hand are x y and 2. ISO 2631-1,1997-, ISO 5349-1,2001.)... 

Vibration Perception. The perception of vibration depends on the body site and on the stimulus firequency. The thresholds in Table 10.2 are typical of those for healthy adults, and are expressed as instantaneous RMS accelerations (i.e., with T 1 s in Eq. (10.2)). The value for whole-body vibration is given in terms of a frequency-weighted acceleration, and so is applicable to vibration at frequencies from 1 to 80 Hz. The values for hand-transmitted vibration are for sinusoidal stimuli applied to the fingertips of males (M) and females (F) at the specified frequencies. 

Brammer, A. J. Dose-Response Relationships for Hand-Transmitted Vibration, Scand. J. Work Environ. Health, 12 284 (1986). 

ISO 5349-1, Mechanical Vibration—Measurement arul Evaluation cf Human Exposure to Hand-Transmitted Vibration—Part I General Guidelines, International Organization for Standardization, Geneva, 2001. 

ISO 5349, Mechanical Vibration Measurement and Assessment of Human Exposure to Hand-Transmitted Vibration, International Standards Organization, Geneva. ISO 2631, Guide for the Evaluation of Human Exposure to Whole-Body Vibration, ISO, Geneva. 

ISO 5349 (1986) Mechanical vibration - guidelines for the measurement and the assessment of human exposure to hand-transmitted vibration. International Organization for Standardization... 

Bovenzi et al. (1995) examined 21 patients (16 women, 5 men) with SSc or localized variants of scleroderma. A significant association was found between exposure to organic solvents (aromatic hydrocarbons) and SSc (3 men, 1 woman). Among the male subjects, an increased odds ratio for SSc was observed for exposure to organic solvents, silica dust, and hand-transmitted vibration. Exposure to solvents and other chemicals was associated, albeit not significantly, with SSc among the women. 

Royal College of Physicians, Hand Transmitted Vibrations, 2 vols, Royal College of Physicians, London (1993)... 

Griffin, M. (2004). Minimum health and safety requirements for workers exposed to hand-transmitted vibration and whole-body vibration in the European Union a review. Occupational and Environmental Medicine, 61(5), 387-397. 

FIGURE 10.1 Frequency weightings for whole-body (W, and WJ and hand-transmitted 0V ) vibration. and Wj are for the z direction and X and y directions, respectively, and are applicable to seated and standing persons (see Fig. 10.2). IF ) is for all directions of vibration entering the hand. The filters are applied to acceleration-time histories a t). ISO 2631-I, I997 ISO 5349-1,2001.)... 

Various solutions have been devised to reduce vibration in hand-held tools and in machinery and vehicles which are worked in or ridden in. For example, the couphng which occurs between moving parts and those parts in contact with the operator, which is needed to transmit vibration to the operator, has been reduced by sandwiching material of less stiffness than steel, e.g. rubber. 

Hand-arm vibration (HAV) means mechanical vibration which is transmitted into the hands and arms during a work activity. 

Raman and IR spectroscopies are complementary to each other because of their different selection rules. Raman scattering occurs when the electric field of light induces a dipole moment by changing the polarizability of the molecules. In Raman spectroscopy the intensity of a band is linearly related to the concentration of the species. IR spectroscopy, on the other hand, requires an intrinsic dipole moment to exist for charge with molecular vibration. The concentration of the absorbing species is proportional to the logarithm of the ratio of the incident and transmitted intensities in the latter technique. 

Near-infrared absorption is therefore essentially due to combination and overtone modes of higher energy fundamentals, such as C-H, N-H, and O-H stretches, which appear as lower overtones and lower order combination modes. Since the NIR absorption of polyatomic molecules thus mainly reflects vibrational contributions from very few functional groups, NIR spectroscopy is less suitable for detailed qualitative analysis than IR, which shows all (active) fundamentals and the overtones and combination modes of low-energy vibrations. On the other hand, since the vibrational intensities of near-infrared bands are considerably lower than those of corresponding infrared bands, optical layers of reasonable size (millimeters, centimeters) may be transmitted in the NIR, even in the case of liquid samples, compared to the layers of pm size which are detected in the infrared. This has important consequences for the direct quantitative study of chemical reactions, chemical equilibria, and phase equilibria via NIR spectroscopy. 

When an isotropic crystal is placed between crossed Nicol prisms, there is extinction, which means that nothing is seen, and the field is perfectly dark. On the other hand, if an optically anisotropic, birefrin-gent crystal is similarly viewed, it will appear colored except at certain positions of rotation, usually 90° apart. At these positions, extinction occurs because the vibration directions of the light transmitted through the... 

HAV is vibration transmitted firom work processes into workers hands and arms. It can be caused by operating hand-held power tools such as ... 

Workers involved in the activity of semi-mechanized tillage were exposed to hands and arms vibration. For vibration analysis the MAESTRO instrument manufactured by OldB coupled to a triaxial accelerometer was fixed at the point where energy was transmitted to the hands. This instrument provides the values of the magnitude of acceleration in ms-2 in the weighted frequencies from 6.3 to 1250 Hz. Digging holes machines brand Stihl BT 121 model were evaluated using the Directive 2002/44/EC the European Community (EUROPEAN PARLIAMENT AND OF THE COUNCIL, 2002). The values set by the Directive for hand and arm are 2.5 m s" to alert level and 5.0 m s to threshold level. 

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