China
Africa
Explore chapters and articles related to this topic
Imaging, Process Control, and Miscellaneous Low-Intensity Applications
Published in Dale Ensminger, Leonard J. Bond, Ultrasonics, 2011
Dale Ensminger, Leonard J. Bond
Ultrasonic attenuation spectra from ultrasound signals provide information about slurry particle size and concentration, and this is reported by Bamberger et al. [136]. As the particle size and the acoustic frequency are changed, the relative importance of attenuation mechanisms changes, and the acoustic attenuation can be dominated by different effects. Three regimes are identified for slurries consisting of solids in a liquid such as fine sand in water, and these are the viscous regime, inertial regime, and Rayleigh scattering regime, which are discussed by Kytömaa [137]. Researchers have used transitions between two regimes, in particular the viscous and inertial regime, to quantify particle size and concentration in real time as discussed by Boxman et al. [138].
Elastooptic Materials
Published in Marvin J. Weber, and TECHNOLOGY, 2020
Two recently synthesized classes of crystals have been identified as having outstanding properties for applications in acoustooptic (AO) devices. These are the mercurous halides and the lead halides. The properties that are important for AO devices are (a) spectral transmission range and optical quality, (b) photoelastic coefficient and related figure of merit, (c) acoustic velocity, and (d) acoustic attenuation coefficient. These properties for the new crystals are presented in the following sections.
Acousto-Optic Scanners and Modulators
Published in Gerald F. Marshall, Glenn E. Stutz, Handbook of Optical and Laser Scanning, 2018
Reeder N. Ward, Mark T. Montgomery, Milton Gottlieb
An overall summary of a few outstanding (in one or another respect) selected AO materials presented in these tables is shown in Figure 11.19. Using figure of merit and acoustic attenuation as criteria of quality, it is clear that a trade-off between these two parameters exists, and that the selection of the optimum material will be determined by the system requirements.
Numerical simulation study of acoustic waves propagation and streaming using MRT-lattice Boltzmann method
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2023
Jaouad Benhamou, Mohammed Jami, Ahmed Mezrhab, Daniel Henry, Valéry Botton
It is now interesting to evaluate the acoustic force induced by the attenuated wave as it is responsible for the development of acoustic streaming. The acoustic force can be determined from the acoustic pressure field generated by the transducer. In the particular case of progressive sinusoidal plane waves, the force can take the following form [25, 26]: where and are the speed of the sound, the acoustic attenuation coefficient, the fluid density, and the acoustic pressure amplitude, respectively. The attenuation coefficient has been given in Eq. (33). The acoustic pressure is obtained from the off-equilibrium density as i.e. Its amplitude can be determined from its rms-value. Indeed, for a pressure wave expressed as the amplitude is:
Drag-type in-situ acoustic measurement system: Design, operation, and experimental results
Published in Marine Georesources & Geotechnology, 2019
Zhengyu Hou, Changsheng Guo, Jingqiang Wang
The values of certain acoustic parameters are essential information in sediment wave propagation models, which are vital to explorations of the sea bottom and understanding underwater acoustic environments (Han et al. 2012; Bonomo and Isakson 2017). These parameters may also provide important information for seafloor engineering, military oceanography, and marine geotechnics (Liu et al. 2013; Meng et al. 2012, 2017; Hou et al. 2018). The sound velocity and acoustic attenuation coefficient are the two most important acoustic parameters that directly govern the effects of acoustic and seismic processes at the seafloor. Two main methods currently exist for obtaining accurate acoustic parameters: sampling measurements and in-situ measurements. The primary challenge encountered during assessments of the acoustic properties of the seafloor is the deformation of the sediment caused by sampling procedures (Hou et al. 2014). In-situ measurement techniques can avoid such disturbances and environmental changes in evaluations of the geotechnical conditions of the seafloor (Neto et al. 2013).
Numerical investigation of spatially nonhomogeneous acoustic agglomeration using sectional algorithm
Published in Aerosol Science and Technology, 2018
Xiaopeng Shang, Bing Feng Ng, Man Pun Wan, Jinwen Xiong, Shmitha Arikrishnan
The acoustic attenuation in particulate medium is mainly caused by two dissipation mechanisms: the particle relaxation by viscosity and the heat transfer from the gas medium to particles. The thermal relaxation time for a particle of density ρp and diameter d are calculated by where Pr is the Prandtl number, μ is the dynamic viscosity of the gas, Cp and Cpg are the specific heat of the particle and gas, respectively, and the dynamic relaxation time is defined by Equation (12).