Experimental Study on Acoustic Characteristics of Particle Breakage Under Combined Shear and Extrusion Load

2021 ◽  
Vol 13 (5) ◽  
pp. 846-856
Author(s):  
Yu Luo Jian ◽  
Tong Xin ◽  
Wu Huang Yi
Keyword(s):  
Structural Parameters ◽  
Sound Intensity ◽  
Test Method ◽  
Motor Speed ◽  
Particle Crushing ◽  
Acoustic Parameters ◽  
Angle Variation ◽  
Acoustic Characteristics ◽  
Loading Process ◽  
Variation Range

The jaw crushing loading process is a typical loading process of combined shearing and extrusion. In this paper, by establishing a complete jaw crushing loading process, the sonic test method is used to determine and analyze the particle crushing law to explore acoustic characteristics of particle crushing under the combined action of shear and extrusion. A jaw crushing tester is used to simulate the jaw crushing process of sand aggregate specimens. A rock-soil sound wave detector is used to measure the sound speed, sound amplitude, and sound intensity during the simulated jaw crushing process. It is found that when the jaw angle variation range is 2.6°, the inlet-outlet ratio is 0.332 and the motor speed is 15 r/min, the sound velocity and the sound amplitude curves fluctuate more drastically and the sound intensity is higher. The crushing evaluation of the sand aggregate specimens, which have experienced crushing simulation, shows that when the jaw angle variation range is 3.0°, the inlet-outlet ratio is 0.332 and the motor speed is 33 r/min, higher crushing energy rate and crushing rate are achieved. Through the comparative analysis of each group’s acoustic parameters and crushing evaluations, it is found that both the acoustic parameters and the crushing evaluations reflect the crushing process, but they have similarities and differences. Therefore, to some extent, the acoustic parameters in the crushing process can be regarded as significant indicators for evaluating the crushing effect. This conclusion may be a reference for optimizing working parameters and structural parameters of crushing equipment.

scholarly journals On the Fictitious Grease Lubrication Performance in a Four-Ball Tester

Lubricants ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 33
Author(s):  
Sravan K. Joysula ◽  
Anshuman Dube ◽  
Debdutt Patro ◽  
Deepak Halenahally Veeregowda
Keyword(s):  
Critical Factor ◽  
Maximum Load ◽  
Test Method ◽  
Extreme Pressure ◽  
Motor Speed ◽  
Low Friction ◽  
Grease Lubrication ◽  
Additive Package ◽  
Variable Frequency Drive ◽  
Lubrication Performance

The extreme pressure (EP) behavior of grease is related to its additives that can prevent seizure. However, in this study following ASTM D2596 four-ball test method, the EP behavior of greases was modified without any changes to its additive package. A four-ball tester with position encoders and variable frequency drive system was used to control the speed ramp up time or delay in motor speed to demonstrate higher grease weld load and lower grease friction that were fictitious. A tenth of a second delay in speed ramp up time had showed an increase in the weld load from 7848 N to 9810 N for grease X and 6082 N to 9810 N for grease Y. Further increase in the speed ramp up time to 0.95 s showed that the greases passed the maximum load of 9810 N that was possible in the four-ball tester without seizure. The mechanism can be related to the delay in rise of local temperature to reach the melting point of steel required for full seizure or welding, that was theoretically attributed to an increase in heat loss as the speed ramp-up time was increased. Furthermore, the speed ramp up time increased the corrected load for grease X and Y. This resulted in lower friction for grease X and Y. This fictitious low friction can be attributed to decrease in surface roughness at higher extreme pressure or higher corrected load. This study suggests that speed ramp up time is a critical factor that should be further investigated by ASTM and grease manufacturers, to prevent the use of grease with fictitious EP behavior.

Decoupling Capability of Levitation Frames for Medium-Low Speed Maglev Trains

2021 ◽  
pp. 2150178
Author(s):  
Junxiong Hu ◽  
Weihua Ma ◽  
Shihui Luo ◽  
Wan Liu ◽  
Tianwei Qu ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Stability Control ◽  
Test Method ◽  
Air Spring ◽  
Low Speed ◽  
End Set

Medium-low speed maglev trains (MSMTs) with a levitation gap of only 8–10[Formula: see text]mm need an adequate decoupling capability on the levitation frames to ensure stability control in levitation, while preventing the train from rolling sideways when in landing. Based on the geometric and kinematic relationships, two types of levitation frames are studied, i.e. levitation frame with end-set air spring (LFEAS) and levitation frame with mid-set air spring (LFMAS). For each levitation frame, the decoupling process and mechanism are analyzed, the analytical equations for the kinematic attitude are derived, the decoupling capability under different excitations is calculated, along with the effect of various structural parameters assessed. In addition, a test method is designed for the rolling of the levitation frame, particularly with the anti-rolling capability of the LFMAS measured. The results indicate that oscillation of the hanger rods and anti-rolling beams can compensate for displacement when the motion of the levitation frame is decoupled, which is the key to the decoupling capability. Also, the position of the anti-rolling devices and the length of hanger rods do not affect significantly the decoupling capability. However, a longer anti-rolling beam is more conducive to decoupling, but it does not affect the anti-rolling capacity of the levitation frame. The maximum roll computed of the LFMAS is 2.84[Formula: see text]mm, which meets the anti-rolling requirement.

scholarly journals Influence of Surface Texture Characteristics on the Noise in Grooving Concrete Pavement

2018 ◽  
Vol 8 (11) ◽  
pp. 2141 ◽  
Author(s):  
Dingbang Wei ◽  
Bo Li ◽  
Zhengwei Zhang ◽  
Feng Han ◽  
Xingjun Zhang ◽  
...  
Keyword(s):  
Surface Texture ◽  
Noise Level ◽  
Sound Intensity ◽  
Statistical Correlation ◽  
Concrete Pavement ◽  
Test Method ◽  
Clear Correlation ◽  
Force Coefficient ◽  
Texture Characteristics ◽  
Pavement Noise

To thoroughly explore the relationship between concrete pavement texture characteristics and tire/pavement noise of grooving concrete pavement, the surface texture, i.e., roughness, macrotexture, and microtexture, was investigated in numerous highway pavements. The On-Board Sound Intensity (OBSI) method was used to test the pavement/tire noise. The statistical correlation between concrete pavement texture characteristics and tire/pavement noise was quantitatively described by two correlation analysis methods for highway concrete pavement: origin of linear regression and the Pearson two-sided test method. The results indicate that the effect of pavement roughness on tire/pavement noise is significant, while the noise level is minor for the flat pavement. The macro texture depth also has a marked impact on the tire/pavement noise. In addition, a large grooving depth of concrete pavement could cause a high tire/pavement noise level; however, there is no clear correlation between side-way force coefficient (SFC) and tire/pavement noise.

On the Relations Between Audio Features and Room Acoustic Parameters of Auralizations

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Salvador Cerdá ◽  
Alicia Giménez ◽  
Radha Montell ◽  
Arturo Barba ◽  
Radu Lacatis ◽  
...  
Keyword(s):  
Room Acoustics ◽  
Subjective Perception ◽  
Audio Signals ◽  
Acoustic Parameters ◽  
Acoustic Characteristics ◽  
Statistical Correlations ◽  
Audio Features ◽  
Musical Characteristics ◽  
Audio Files ◽  
Musical Audio

The usual parameters in room acoustics are used to quantify the acoustic characteristics of rooms and their relation to the subjective perception of transmitted signals. Audio features (calculated with MIRToolbox) have been designed to study the relationships between the characteristics of musical audio files and their subjective perception. Both musical characteristics and acoustic parameters are oriented towards acoustic perception. By using auralizations with calibrated models of auditoriums and tools from the MIRtoolbox it is possible to jointly work with the calculation of audio features and room parameters. In this work, the statistical correlations between C80, STI, D50, EDT, RT and certain audio features have been analyzed. The Pearson r values are higher than 0.8 in all cases. These high correlations enable acoustic parameters to be calculated from the musical characteristics of auralized audio signals.

scholarly journals The Acoustics of the Double Elliptical Vault of the Royal Palace of Caserta (Italy)

2021 ◽  
Author(s):  
Umberto Berardi ◽  
Gino Iannace ◽  
Amelia Trematerra
Keyword(s):  
Spatial Distribution ◽  
Seventeenth Century ◽  
Sound Source ◽  
Acoustic Parameters ◽  
Acoustic Characteristics ◽  
Royal Palace

This work investigates the acoustic characteristics of the double elliptical vault, which overlooks the Grand Staircase of the Royal Palace of Caserta (Italy). The Royal Palace was built by the architect Luigi Vanvitelli in the Seventeenth Century and it is the largest royal building in Italy. The double elliptical vault presents a great scenography effect. Inside the vault, on the planking level, musicians used to play for the king and his guests when the royal procession, going up the grand staircase, entered the royal apartments, creating astonishment among the guests who heard the music without understanding from where it was coming. Since the musicians were inside the vault, the long reverberation made the listeners perceive the vault to be enveloped by the music. To investigate this effect, the acoustic characteristics of the double vault were measured, putting the sound source on the planking level of the vault, while the microphones were put along the staircase and in the vestibule towards the royal apartments. Finally, the spatial distribution of several acoustic parameters is evaluated also using architectural acoustic simulations.

scholarly journals Vibroacoustic characteristics analysis of a planetary gear reducer considering the exterior housing structure

2021 ◽  
Vol 12 (1) ◽  
pp. 539-557
Author(s):  
Lihong Jin ◽  
Junpeng Shao ◽  
Xigui Wang ◽  
Yongmei Wang ◽  
Baixue Fu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Dynamic Characteristics ◽  
Optimization Design ◽  
Structural Parameters ◽  
Planetary Gear ◽  
Design Parameters ◽  
Weak Links ◽  
Acoustic Characteristics ◽  
Transfer Path

Abstract. Previous studies have attempted to identify weak links in the dynamic characteristics of the planetary gear reducer (PGR) exterior body structure (EBS). Through numerical simulation, these studies analyzed the mode and natural frequencies and the vibration types of each order of the EBS. However, these scholars have never focused on the main factors affecting the dynamic characteristics of the EBS of this subject. This study in the topic has analyzed the vibroacoustic characteristics of an EBS and optimized its design using numerical simulation. Herein, the contribution of the vibration transfer path from the excitation points on the exterior body to the machine foot is emphatically revealed, and the influences of the main structural parameters on the transfer characteristics are discussed. An optimal EBS for a PGR with lower acoustic vibrations is designed in detail, and a composite EBS with damping vibration attenuation and acoustic absorption is proposed. The radiation acoustic characteristics without acoustic protection and damping materials are analyzed. These research results are implemented in order to realize the dynamic characteristics, transmission, and radiation acoustic characteristics as objects of optimization, and the structural design parameters of the PGR exterior body are deeply optimized using dynamic modification and sensitivity analysis. This topic focuses on the vibroacoustic coupling of EBS in stationary fluid and average flow field. Based on the analysis method of theoretical modeling and numerical calculation, the EBS dynamic response and vibroacoustic characteristics under the action of frontal excitation external acoustic flow field are studied, which will be beneficial to explore the comprehensive optimization design of PGR dynamic and vibroacoustic properties.

Intelligibility and the Acoustic Characteristics of Speech in Amyotrophic Lateral Sclerosis (ALS)

1994 ◽  
Vol 37 (3) ◽  
pp. 496-503 ◽  
Author(s):  
Moira Mulligan ◽  
Joseph Carpenter ◽  
Joanne Riddel ◽  
Maureen Kenny Delaney ◽  
Gary Badger ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Transition Rate ◽  
Transition Rates ◽  
Single Word ◽  
Acoustic Parameters ◽  
Acoustic Characteristics ◽  
Als Patients ◽  
The Relationship ◽  
Lateral Sclerosis

The purpose of this study was to analyze the changes in specific speech parameters in 14 patients, 7 dysarthric and 7 non-dysarthric, with amyotrophic lateral sclerosis (ALS), over a 6-month period. Measurements of single word intelligibility, F2 formant trajectories (extent, duration and rate) and diadochokinetic rate showed decreased performance in dysarthric patients as compared to non-dysarthric patients at baseline. F2 transition rates of less than 4 Hz/msec were seen only in dysarthric ALS patients. A relationship between the F2 transition rate and single word intelligibility was noted for patients with moderate to high intelligibility, but at lower levels of intelligibility the F2 rate reached a plateau despite continued decline in intelligibility. Our results support the need for frequent evaluation of dysarthric ALS patients to better understand the relationship between intelligibility and the acoustic parameters of speech.

scholarly journals The Effects of the Structural and Acoustic Parameters of the Skull Model on Transcranial Focused Ultrasound

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5962
Author(s):  
Hao Zhang ◽  
Yanqiu Zhang ◽  
Minpeng Xu ◽  
Xizi Song ◽  
Shanguang Chen ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Focused Ultrasound ◽  
Structural Parameters ◽  
Radius Of Curvature ◽  
Acoustic Parameters ◽  
Unit Distance ◽  
Technical Problems ◽  
Skull Model ◽  
Transcranial Focused Ultrasound ◽  
Acoustic Speed

Transcranial focused ultrasound (tFUS) has great potential in brain imaging and therapy. However, the structural and acoustic differences of the skull will cause a large number of technical problems in the application of tFUS, such as low focus energy, focal shift, and defocusing. To have a comprehensive understanding of the skull effect on tFUS, this study investigated the effects of the structural parameters (thickness, radius of curvature, and distance from the transducer) and acoustic parameters (density, acoustic speed, and absorption coefficient) of the skull model on tFUS based on acrylic plates and two simulation methods (self-programming and COMSOL). For structural parameters, our research shows that as the three factors increase the unit distance, the attenuation caused from large to small is the thickness (0.357 dB/mm), the distance to transducer (0.048 dB/mm), and the radius of curvature (0.027 dB/mm). For acoustic parameters, the attenuation caused by density (0.024 dB/30 kg/m3) and acoustic speed (0.021 dB/30 m/s) are basically the same. Additionally, as the absorption coefficient increases, the focus acoustic pressure decays exponentially. The thickness of the structural parameters and the absorption coefficient of the acoustic parameters are the most important factors leading to the attenuation of tFUS. The experimental and simulation trends are highly consistent. This work contributes to the comprehensive and quantitative understanding of how the skull influences tFUS, which further enhances the application of tFUS in neuromodulation research and treatment.

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