Use of Near-Field Acoustic Levitation in Experimental Sliding Contact

2006 ◽  
Vol 74 (4) ◽  
pp. 816-820 ◽  
Author(s):  
T. A. Stolarski ◽  
C. I. Woolliscroft
Keyword(s):  
Near Field ◽  
Separation Distance ◽  
Sliding Contact ◽  
The Self ◽  
Experimental Results ◽  
Acoustic Levitation ◽  
Plate Material ◽  
Acoustic Reflection ◽  
Piezo Electric

The paper presents an investigation into producing the self-levitation effect using piezo-electric actuators (PZTs). Self-levitation has been demonstrated and results are presented and discussed. A relationship between the levitation distance and weight of the levitating sample has been found. In addition, the orientation and position of the PZTs has been found to affect the levitation distance. Modal shapes of the vibration plates used have been produced through modeling and found to accurately correlate with the experimental results found. Additional evidence suggests that the type of vibration plate material affects the separation distance, possibly due to the material’s properties of acoustic reflection.

A Study of Near-Field Entrainment in Gas Jets and Sprays Under Diesel Conditions

1999 ◽  
Vol 122 (2) ◽  
pp. 385-395 ◽  
Author(s):  
Scott Post ◽  
Venkatraman Iyer ◽  
John Abraham
Keyword(s):  
Rate Constant ◽  
Computational Study ◽  
Near Field ◽  
The Self ◽  
Experimental Results ◽  
Entrainment Rate ◽  
Gas Jets ◽  
Similar Region ◽  
Mass Entrainment ◽  
Self Similar

This paper presents a computational study of entrainment characteristics in the near-field of gas jets under atmospheric and Diesel conditions and sprays under Diesel conditions. Computed flowfield information is used to estimate the rate of mass entrainment in the jet and derive the entrainment rate constant. The value of the entrainment rate constant is compared to experimental results in the literature. It is found that the computed values of the constant in the near-field are less than the values in the self-similar region of the jet with the values increasing monotonically from the orifice to the self-similar region. These results are consistent with experimental results. In the case of sprays, it is found that it is difficult to arrive at firm conclusions because the results are sensitive to several parameters that are not well known and to the numerics. The computed results for sprays are also discussed relative to measurements in sprays quoted in the literature. [S0098-2202(00)00802-6]

Lateral Tire Forces on Wet Roads

1977 ◽  
Vol 5 (2) ◽  
pp. 75-82 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Normal Load ◽  
The Self ◽  
Experimental Results ◽  
Slip Angle ◽  
Tire Model ◽  
Side Force ◽  
Tire Forces

Abstract Expressions are derived for side force and self-aligning torque of a simple tire model on wet roads with velocity-dependent friction. The results agree qualitatively with experimental results at moderate speeds. In particular, the theory correctly predicts that the self-aligning torque can become negative under easily realizable circumstances. The slip angle at which the torque reverses sign should increase with the normal load.

scholarly journals Onset of the Mach Reflection of Zel’dovich–von Neumann–Döring Detonations

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 314
Author(s):  
Tianyu Jing ◽  
Huilan Ren ◽  
Jian Li
Keyword(s):  
Hot Spot ◽  
Mach Reflection ◽  
Near Field ◽  
The Self ◽  
Small Scale ◽  
Mach Stem ◽  
Self Similarity ◽  
Von Neumann ◽  
Similarity Problem ◽  
Self Similar

The present study investigates the similarity problem associated with the onset of the Mach reflection of Zel’dovich–von Neumann–Döring (ZND) detonations in the near field. The results reveal that the self-similarity in the frozen-limit regime is strictly valid only within a small scale, i.e., of the order of the induction length. The Mach reflection becomes non-self-similar during the transition of the Mach stem from “frozen” to “reactive” by coupling with the reaction zone. The triple-point trajectory first rises from the self-similar result due to compressive waves generated by the “hot spot”, and then decays after establishment of the reactive Mach stem. It is also found, by removing the restriction, that the frozen limit can be extended to a much larger distance than expected. The obtained results elucidate the physical origin of the onset of Mach reflection with chemical reactions, which has previously been observed in both experiments and numerical simulations.

Acoustic radiation simulation and pre-stress effect on compact acoustic levitation platform

2019 ◽  
Vol 33 (07) ◽  
pp. 1950080 ◽  
Author(s):  
Bin Wei ◽  
Yongyong He ◽  
Wei Wang
Keyword(s):  
Pressure Distribution ◽  
Acoustic Radiation ◽  
Near Field ◽  
Parameters Optimization ◽  
Squeeze Film ◽  
Acoustic Levitation ◽  
Stress Effect ◽  
Biological Engineering ◽  
Loop Control ◽  
Close Loop Control

In order to satisfy the requirements of precise components with tidiness, low power and high stability in the field of biological engineering, medical equipment and semiconductors etc. a pre-stress acoustic transport prototype without horn was proposed in this paper. The mechanism of levitation and transport which is driven by orthogonal waves was revealed by the analysis of waveform and squeeze film characteristics in high-frequency exciting condition; also, the electric, solid and acoustic coupled finite element method (FEM) was established to investigate the effect of pre-stress and acoustic pressure distribution in the near field. The levitation and driving capacity of near field acoustic levitation (NFAL) transport platform without horns can be proved in this experiment and further to achieve the goal of parameters optimization. The theoretical and experimental results indicate that the pre-stress has a significant effect on resonant frequency and levitating stability, the pre-stress are determined by the DC voltage offset which is related to the system working point so that we cannot increase the offset and exciting voltage unlimitedly to improve the stability. At the same time, the calculated pressure distribution of acoustic radiation can generally reflect the regional bearing capacity in near and far field for levitation. These achievements can partly solve the problem of accuracy design of prototype and thickness of gas film, supporting for accuracy close loop control of levitating height.

RAMAN SPECTRA OF THE H2SO4–SO3 AND D2SO4–SO3 SYSTEMS: EVIDENCE FOR THE OCCURRENCE OF POLYSULPHURIC ACIDS

1962 ◽  
Vol 40 (4) ◽  
pp. 658-674 ◽  
Author(s):  
R. J. Gillespie ◽  
E. A. Robinson
Keyword(s):  
Sulphuric Acid ◽  
Raman Spectra ◽  
Ionic Species ◽  
The Self ◽  
Experimental Results ◽  
Similar Work ◽  
Stretching Vibrations ◽  
Sulphur Trioxide ◽  
High Concentrations

The Raman spectra of oleums, i.e. mixtures of sulphur trioxide and sulphuric acid, have been re-examined. Similar measurements on the sulphur trioxide – deuterosulphuric acid (D2SO4) system are also reported. The experimental results and conclusions of previous similar work on oleums are discussed. By comparison of the spectra of oleums with those of the polysulphuryl halides it is shown that the polysulphuric acids H2S2O7 and H2S3O10 are present in this system. The increase in the frequency of the SO2 stretching vibrations with increasing concentration of sulphur trioxide gives evidence for the existence of higher polysulphuric acids such as H2S4O13 at high concentrations of sulphur trioxide. In relatively concentrated oleum, sulphur trioxide monomer and trimer are also present. It is shown that the self-dissociation of liquid H2S2O7 gives mainly molecular H2S2O10 and H2SO4 and not ionic species. The conclusions reached from the interpretation of the Raman spectra of the D2SO4–SO3 system are similar to those arrived at for sulphuric acid oleums. The spectra of solutions of NaHSO4 in oleums were also examined, and are discussed.

scholarly journals A Self-Supervised Tibetan-Chinese Vocabulary Alignment Method based on Adversarial Learning

2021 ◽  
Author(s):  
Enshuai Hou ◽  
Jie zhu
Keyword(s):  
The Self ◽  
Experimental Results ◽  
Chinese Characters ◽  
Training Method ◽  
Alignment Method ◽  
Adversarial Learning ◽  
Semantic Correlation ◽  
Data Alignment ◽  
Similarity Calculation ◽  
Adversarial Training

Tibetan is a low-resource language. In order to alleviate the shortage of parallel corpus between Tibetan and Chinese, this paper uses two monolingual corpora and a small number of seed dictionaries to learn the semi-supervised method with seed dictionaries and self-supervised adversarial training method through the similarity calculation of word clusters in different embedded spaces and puts forward an improved self-supervised adversarial learning method of Tibetan and Chinese monolingual data alignment only. The experimental results are as follows. First, the experimental results of Tibetan syllables Chinese characters are not good, which reflects the weak semantic correlation between Tibetan syllables and Chinese characters; second, the seed dictionary of semi-supervised method made before 10 predicted word accuracy of 66.5 (Tibetan - Chinese) and 74.8 (Chinese - Tibetan) results, to improve the self-supervision methods in both language directions have reached 53.5 accuracy.

scholarly journals Experimental Study and Extended Finite Element Simulation of Fracture of Self-Compacting Rubberized Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xinquan Wang ◽  
Hongguo Diao ◽  
Yunliang Cui ◽  
Changguang Qi ◽  
Shangyu Han
Keyword(s):  
Finite Element ◽  
Loading Rate ◽  
High Performance Concrete ◽  
The Self ◽  
Experimental Results ◽  
Crack Mouth Opening Displacement ◽  
Displacement Curve ◽  
Rubberized Concrete ◽  
Extended Finite Element ◽  
Self Compacting Concrete

Self-compacting rubberized concrete (SCRC) is a high-performance concrete that can achieve compacting effect by self-gravity without vibration during pouring. Because of its excellent fluidity, homogeneity, and stability, the application of self-compacting concrete in engineering can improve work efficiency and reduce project cost. The effects of loading rate on the fracture behavior of self-compacting concrete were studied in this paper. Three-point bend (TPB) tests were carried out at five loading rates of 1, 0.1, 0.001, 0.0001, and 0.00001 mm/s. The dimensions of the specimens were 100  mm × 100 mm × 400 mm. A precast crack was set in the middle of the specimen with a notch-depth ratio of 0.4. The experimental results show that the peak load on the load-CMOD (crack mouth opening displacement) curve gradually increases with the increase of the loading rate. Although the fracture energy a presented greater dispersion under the loading rate of 1 mm/s, the overall changes were still rising with the increase of the loading rate. Besides studying the softening characteristics of the self-compacting concrete, the constitutive softening curve of the self-compacting concrete was obtained using the bilinear model. Finally, curved three-point bending beams were simulated by using the extended finite element method based on ABAQUS. The fracture process of the self-compacting concrete under different loading conditions was analyzed more intuitively. The simulation results were compared with the experimental results, and the same conclusions were obtained.

scholarly journals Multivariate Self-Dual Morphological Operators Based on Extremum Constraint

2015 ◽  
Vol 2015 ◽  
pp. 1-16
Author(s):  
Tao Lei ◽  
Yi Wang ◽  
Weiwei Luo
Keyword(s):  
Noise Removal ◽  
Complete Characterization ◽  
The Self ◽  
Experimental Results ◽  
Watershed Transformation ◽  
Morphological Operators ◽  
Self Duality ◽  
Multichannel Images ◽  
Duality Property ◽  
Image Details

Self-dual morphological operators (SDMO) do not rely on whether one starts the sequence with erosion or dilation; they treat the image foreground and background identically. However, it is difficult to extend SDMO to multichannel images. Based on the self-duality property of traditional morphological operators and the theory of extremum constraint, this paper gives a complete characterization for the construction of multivariate SDMO. We introduce a pair of symmetric vector orderings (SVO) to construct multivariate dual morphological operators. Furthermore, utilizing extremum constraint to optimize multivariate morphological operators, we construct multivariate SDMO. Finally, we illustrate the importance and effectiveness of the multivariate SDMO by applications of noise removal and segmentation performance. The experimental results show that the proposed multivariate SDMO achieves better results, and they suppress noises more efficiently without losing image details compared with other filtering methods. Moreover, the proposed multivariate SDMO is also shown to have the best segmentation performance after the filtered images via watershed transformation.

Experimental results on wavefront correction using the self-coherent camera

2012 ◽  
Author(s):  
M. Mas ◽  
P. Baudoz ◽  
J. Mazoyer ◽  
R. Galicher ◽  
G. Rousset
Keyword(s):  
The Self ◽  
Experimental Results ◽  
Wavefront Correction
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