Study on Ultrasonic Cavitaion Field of Power Ultrasonic Honing

2013 ◽  
Vol 690-693 ◽  
pp. 3284-3288 ◽  
Author(s):  
Ce Guo ◽  
Xi Jing Zhu ◽  
Guo Dong Liu
Keyword(s):  
High Frequency ◽  
Theoretical Calculations ◽  
Sound Intensity ◽  
Threshold Value ◽  
Cutting Fluid ◽  
Precision Grinding ◽  
Cavitation Effect ◽  
Ultrasonic Sound ◽  
Great Amplitude ◽  
Power Ultrasonic

Power ultrasonic honing is an advanced precision grinding technology, with ultrasonic vibration applied on the oilstone surface. The high frequency vibration of oilstone make cutting fluid appear cavitation effect, which make acoustic field of power ultrasonic honing present instability and complex, and even appear chatter and noise. In this paper, the cavitation mechanism of power ultrasonic honing is explained, and the oilstone radiated pressure are obtained. Furthermore, the dynamics and radiated pressure model of cavitation bubble in the grinding area is established and analysed. Finally, the pressure of oilstone surface is measured by ultrasonic sound intensity measuring instrument. It shows that the acoustic pressure radiated from oilstone with theoretical calculations and simulations are one order higher than cavitational threshold value of cutting fluid, ultrasonic cavitation occurs. Cavitation bubbles have been nonlinear vibration with high frequency, great amplitude and up to 107 Pa orders pressure, which seriously affect the workpiece processing quality and oilstone life. Comparisons between theoretical analysis and experimental verification have shown a satisfactory agreement.

The Study of Method for Calculating Geometric Average Sound Intensity in Scattering Field

2010 ◽  
Vol 458 ◽  
pp. 185-191
Author(s):  
Feng Li Luo ◽  
Guang Yu Li
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Computing Time ◽  
Sound Intensity ◽  
Frequency Range ◽  
Average Value ◽  
Geometric Average ◽  
Scattering Field ◽  
Measurement Efficiency ◽  
Frequency Area

When calculating sound intensity by indirectly measuring way, the sound pressures obtained from two microphones should be mathematically averaged as the sound pressure of measured point. The research showed that the method exists lower of allowable value in the high frequency area. Using the geometric average value of two measured points to replace the sound pressure of measured point, studying the measurement of sound intensity in scattering field, the errors from which were compared. The result showed that the error of geometric average sound intensity was more flat than that of mathematic average. So the sound intensity obtained from geometric average sound pressure is more suitable for the measurement of a wider frequency range. And the computing time is short, which can raise the measurement efficiency and the real-time of measurement.

scholarly journals Piezoelectric Energy Harvesting with an Ultrasonic Vibration Source

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Tao Li ◽  
Pooi Lee
Keyword(s):  
Energy Harvesting ◽  
High Power ◽  
High Frequency ◽  
Energy Harvester ◽  
Impedance Matching ◽  
Low Frequency ◽  
Vibration Source ◽  
Piezoelectric Energy ◽  
Power Ultrasonic ◽  
Ultrasonic Cutting

A piezoelectric energy harvester was developed in this paper. It is actuated by the vibration leakage from the nodal position of a high-power ultrasonic cutting transducer. The harvester was excited at a low displacement amplitude (0.73 µmpp). However, its operation frequency is quite high and reaches the ultrasonic range (24.4 kHz). Compared with another low frequency harvester (66 Hz), both theoretical and experimental results proved that the advantages of this high frequency harvester include (i) high current generation capability (up to 20 mApp compared to 1.3 mApp of the 66 Hz transducer) and (ii) low impedance matching resistance (500 Ω in contrast to 50 kΩ of the 66 Hz transducer). This energy harvester can be applied either in sensing, or vibration controlling, or simply energy harvesting in a high-power ultrasonic system.

scholarly journals Acoustical study on spectral characteristics of teachers’ English vocalization

2021 ◽  
Vol 257 ◽  
pp. 02027
Author(s):  
Yao Xiao ◽  
Yue-Zhe Zhao
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Sound Pressure ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Sound Intensity ◽  
English Teaching ◽  
Female Teachers ◽  
Acoustical Study ◽  
Second Peak

With the increase of English teaching courses, the specific vocal characteristics of teachers in English teaching are studied and used as the basic data for the design of teachers’ spatial acoustics. In order to study this problem, three different English voice materials were read in a anechoic room under three sound intensity levels: large, medium and small, respectively, so as to analyse the equivalent continuous sound pressure level (SPL) and frequency characteristic curves of male and female teachers at 0.3m. In the low frequency band, the SPL increases as the frequency increases. In the mid-frequency band, the SPL reaches the first peak, then decreases briefly as the frequency increases, then increases again to the second peak, and then decreases again briefly as the frequency increases. Then increase again to the third peak. In the high frequency band, the SPL decreases as the frequency increases.

scholarly journals Randomized control trial evaluating the effectiveness of ear plugs in hearing loss in NICU preterm babies

2020 ◽  
Vol 7 (4) ◽  
pp. 914
Author(s):  
Fathma Thahmi Shingeri ◽  
Ashvij R. Shriyan ◽  
Roshan Ann Maben ◽  
Santosh T. Soans
Keyword(s):  
Hearing Loss ◽  
High Frequency ◽  
Randomized Control Trial ◽  
Sound Intensity ◽  
Control Group ◽  
Sound Levels ◽  
Preterm Babies ◽  
Randomized Control ◽  
Hearing Damage ◽  
To Receive

Background: The prevalence of hearing loss is higher in neonates admitted to NICU compared to the general population. Preterm babies are more vulnerable to the hearing damage due to their immature inner ear exposing them to various high frequency noises in the NICU to which they were not accustomed. Most NICU in India exceed the recommended sound levels. In order to reduce damage to the ears, foam-based earplugs are used to reduce the sound intensity reaching the ears of these premature babies.Methods: Babies admitted to NICU are allocated alternatively to receive earplugs or not. Cases are preterm babies with earplugs and controls are the ones without earplugs. The incidence of hearing loss is found by OAE testing of the ears at the end of NICU stay.Results: Out of 40 in each group, 6 babies in control group failed the OAE compared the 3 in the earplug group. Babies who did wear earplugs had longer period of NICU stay.Conclusions: Use of earplugs in babies admitted to NICU reduced the incidence of hearing loss and also length of NICU stay. 

High‐frequency, high‐power ultrasonic chemical reactors

2004 ◽  
Vol 116 (4) ◽  
pp. 2540-2541
Author(s):  
Michael Hoffmann ◽  
Timothy Lesko ◽  
Agustin Colussi
Keyword(s):  
High Power ◽  
High Frequency ◽  
Chemical Reactors ◽  
Power Ultrasonic

The lung-eardrum pathway in three treefrog and four dendrobatid frog species: some properties of sound transmission.

1994 ◽  
Vol 195 (1) ◽  
pp. 329-343 ◽  
Author(s):  
G Ehret ◽  
E Keilwerth ◽  
T Kamada
Keyword(s):  
High Frequency ◽  
Body Wall ◽  
Low Frequency ◽  
Sound Intensity ◽  
The Body ◽  
Response Curves ◽  
Low Frequencies ◽  
Best Response ◽  
Lateral Body ◽  
Frequency Components

Frequency-response curves of the tympanum and lateral body wall (lung area) were measured by laser Doppler vibrometry in three treefrog (Smilisca baudini, Hyla cinerea, Osteopilus septentrionalis) and four dendrobatid frog (Dendrobates tinctorius, D. histrionicus, Epipedobates tricolor, E. azureiventris) species. The high-frequency cut-off of the body wall response was always lower than that of the tympanum. The best response frequencies of the lateral body wall were lower than those of the tympanum in some species (S. baudini, O. septentrionalis, D. tinctorius), while in the others they were rather similar. Best tympanic frequencies and best body wall response frequencies tended to differ more with increasing body size. Stimulation of the tympanum by sound transfer through 3.14 mm2 areas of the lateral body wall showed that the lung-eardrum pathway can be in two states, depending on breathing activity within the lungs: 44% (in Smilisca), 39% (in Hyla) and 31% (in Osteopilus) of the eardrum vibrations were 2.5-8 times (8-18 dB) larger when the frogs were breathing with the lungs compared with non-breathing conditions. The vibration amplitudes of the tympanum and lateral body wall of the treefrogs followed the same dependence on sound intensity, only absolute amplitudes differed between species. Our results suggest that the lung-eardrum pathway attenuates high-frequency components of species-specific calls and enhances low-frequency components. In addition, an amplitude modulation is imposed on the low frequencies during the rhythm of breathing.

Measurement of very high frequency (VHF) sound in our daily experiences

2021 ◽  
Vol 263 (2) ◽  
pp. 4275-4282
Author(s):  
Koki Harusawa ◽  
Yumi Inamura ◽  
Masaaki Hiroe ◽  
Hideyuki Hasegawa ◽  
Kentaro Nakamura ◽  
...  
Keyword(s):  
Sound Source ◽  
High Frequency ◽  
Microphone Array ◽  
Sound Intensity ◽  
Wide Frequency Range ◽  
The Body ◽  
Very High Frequency ◽  
Pure Tones ◽  
Ventilation Duct ◽  
Very High

Recently, it is frequently reported that very high frequency (VHF) sounds are emitted from daily necessaries such as home electric appliances. Although we measured VHF sounds from home electric appliances in our previous study, the origins of such VHF sounds have not yet been identified. In the present study, we tried to identify the VHF sound source in each home electric appliance using a "sound camera", which visualizes the spatial distribution of the sound intensity using a microphone array. The sound camera visualized the location of the sound source at frequencies from 2 to 52 kHz with a field of view of 63 degrees. The sound camera elucidated that the VHF sounds were emitted from the power source of a LET light, the ventilation duct of an electric fan, and the body of an IH cooker. Their frequency characteristics were dependent on the sound source, i.e., combinations of pure tones in the LED light and distributing in a wide frequency range in the electric fan.

Effects of High Density Ultrasonic Field Coupling on the Microstructures and Properties of Al-Si Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1981-1988 ◽  
Author(s):  
Ying Long Li ◽  
Hua Ding ◽  
Fu Rong Cao
Keyword(s):  
Liquid Phase ◽  
Acoustic Streaming ◽  
Sound Intensity ◽  
Large Degree ◽  
Ultrasonic Field ◽  
High Density ◽  
Field Coupling ◽  
Cavitation Effect ◽  
Eutectic Si ◽  
Equiaxed Grains

The effects of high density ultrasonic field coupling on the microstructures and properties of Al-12Si alloy were investigated. It is shown that when the melt undergoes ultrasonic coupling processing prior to solidification, the nucleation rate of liquid phase can be raised to make α(Al) dendrite transform towards near equiaxed grains, the growth of Si phase is restrained and eutectic Si microstructure is refined due to acoustic streaming effect and thermal mechanism; When the melt undergoes ultrasonic coupling processing during the melt solidification, large degree of supercooling is produced in the liquid phase in the solidification interface front edge to reduce the critical radius of crystal nucleus and critical work of nucleation and break up, rupture by melting and refine the Si phase to improve obviously the strength of Al-12Si alloy due to its cavitation effect, acoustic streaming action and heat undulation; The crushing effect of ultrasonic coupling on Si phase occurs mainly during the crystallizing solidification and threshold sound intensity exists.

Changing the Future?: Development and Application of Pedestrian Safety Performance Functions to Prioritize Locations in Seattle, Washington

2017 ◽  
Vol 2659 (1) ◽  
pp. 212-223 ◽  
Author(s):  
Libby Thomas ◽  
Bo Lan ◽  
Rebecca L. Sanders ◽  
Alexandra Frackelton ◽  
Spencer Gardner ◽  
...  
Keyword(s):  
High Frequency ◽  
Empirical Bayes ◽  
Threshold Value ◽  
Safety Performance ◽  
Crash Prediction ◽  
Safety Improvement ◽  
Safety Performance Functions ◽  
Pedestrian Crashes ◽  
Crash Types ◽  
Treatment Priorities

This study aimed to use robust analysis methods to identify and screen locations at risk for pedestrian crashes and injuries to help Seattle, Washington, a Vision Zero city, broaden treatment priorities beyond only high-crash locations. For this objective, data from the entire network were used to develop safety performance functions (SPFs) for two pedestrian crash types: total pedestrian crashes at intersections (a high frequency type) and a subset of intersection crashes involving through motorists striking crossing pedestrians (a high severity type). Many variables from roadway, built environment, census, and activity measures were tested. A similar but not identical set of variables, including measures of activity and intersection size and complexity, significantly contributed to crash prediction in both models. Pedestrian volume exhibited a curved relationship to crashes and demonstrated a tendency for expected crashes to begin to decline above a threshold value; however, the causes of this relationship were unknown. The SPFs were used in several ranking methods, including SPF-predicted crashes, empirical Bayes estimated crashes, and potential for safety improvement, to aid in prioritization of locations that might have been candidates for safety improvement but that had not necessarily experienced a high frequency of crashes. On the basis of this example, this approach is feasible for jurisdictions that wish to be more proactive in addressing potential crashes and injuries. Jurisdictions must, however, begin routinely collecting the data needed to implement the method efficiently.

Sign in / Sign up

Export Citation Format

Share Document