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Noise and vibration
Published in Sue Reed, Dino Pisaniello, Geza Benke, Principles of Occupational Health & Hygiene, 2020
In this chapter, the recognition, evaluation and control of noise and vibration are examined in general terms. The H&S practitioner is referred to the references for more detailed treatments. The chapter also introduces the phenomena of acoustic shock and ototoxicity. Acoustic shock is a particular concern for workers in the call-centre industry and emergency services control rooms, and can have severe health consequences if no adequate protective measures are put in place.
Overtaking phenomenon of nonlinear ultra-low frequency multi-shock structures in ultra-relativistic degenerate plasmas
Published in Radiation Effects and Defects in Solids, 2021
E. F. El-Shamy, E. A. Elghmaz, H. Elhosiny Ali, A. A. Ibraheem, M. Mahmoud, M.O. A. El Ghazaly
It is interesting to mention here that we can apply the term NULF shock waves instead of ion-acoustic shock waves because the inertia is supplied by the heavier ions, while the restoring force is given by the degenerate pressure of the lighter ions and electrons. Therefore, NULF shock waves are propagated in comparison with ion-acoustic shock waves in normal plasmas (i.e. electron-ion plasmas). In this present case, applying the reductive perturbation method (36), we first introduce the independent variables: where is a small and real parameter, and is the unknown propagation speed of shock waves normalized by the ion acoustic speed. In addition, the dependent variables are expanded as where Substituting (6) and (7) into the simulation model and collecting the lowest-order terms in , we can obtain the following relations:
Evolution of cylindrical/spherical shock formation in a dusty plasma with nonadiabatic dust charge variation
Published in Waves in Random and Complex Media, 2022
Figure 3 shows the effect of superthermality index of ions on the shock structures for and 10.5 depicted by blue solid, black dashed and red dashed dot respectively. Other parameters are , and at . It is observed that the dust acoustic shock wave amplitude decreases with an increase in ion superthermality (low value of κ). A nonlinear effect is decreased with an increase in κ. Additionally, Figure 3(a–c) imply that when one departs from the nonplanar (cylindrical/spherical) to planar geometry, the amplitude of the wave decreases more rapidly. Such declining behavior persists as time passes because amplitude component . We can state that the rise in the ion superthermality (low value of ) favors the occurrence of shock waves of small amplitude. These findings are similar to those of Chen et al. [30]. Figure 4 provides the information about the variation in amplitude of dust acoustic shock waves with dust to ion temperature ratio (θ) for planar, cylindrical and spherical geometry with and at . The amplitude of dust acoustic shock wave decreases with increase in θ. By increasing the value of θ actually, increases, which implies the random motion of dust is becoming stronger. Consequently, this random motion degrades the shock formation by reducing its amplitude as demonstrated in Figure 4.
Assessment of Laser-Generated Ultrasonic Total Focusing Method for Battery Cell Foil Weld Inspection
Published in Research in Nondestructive Evaluation, 2023
Dmitriy D. Bruder, Megan E. McGovern, Robin James, Teresa J. Rinker, Vineet Gattani
Comparable to conventional piezoelectric transducer generated ultrasound, various wave modes are present in laser-generated ultrasound, some which are regime specific. Additionally, operation in the ablation regime will generate an air acoustic shock wave. The remainder of this subsection will detail both the thermoelastic and ablation laser ultrasound regimes and compare the advantages and limitations of laser ultrasound with respect to conventional piezoelectric transducers.