A Layered Notch Filter for High-Frequency Dynamic Isolation

1989 ◽  
Vol 111 (1) ◽  
pp. 17-24 ◽  
Author(s):  
J. L. Sackman ◽  
J. M. Kelly ◽  
A. E. Javid
Keyword(s):  
High Frequency ◽  
Plane Waves ◽  
Notch Filter ◽  
Theoretical Development ◽  
Parallel Plates ◽  
Layered Composites ◽  
Mechanical Filter ◽  
Specific Frequency ◽  
Working Principle ◽  
High Frequency Vibrations

An efficient method of isolation from high-frequency vibrations is the use of periodically layered composites acting as a mechanical filter. This device is a periodically layered stack of alternating materials with widely different densities and stiffnesses. The working principle of the device is wave reflection, and the device becomes increasingly effective when there is a large impedance mismatch which leads to rapid attenuation of an input wave for certain frequency ranges. This filter acts only in specific frequency bands. At other frequencies, it will transmit the vibratory energy unmodified, thus acting as a mechanical notch filter. The theoretical development of the mechanical notch filter is based on the theory of waves in periodically layered media. Floquet theory is used to solve the equations for the propagation of plane waves through a laminated system of parallel plates of different materials when the direction of propagation is normal to the plates. Several experiments were conducted to prove the validity of the mechanical notch filter concept. These experiments demonstrated that the theory is correct and that the results have practical application.

Simulation of vibration piercing of pipe blank at press

2020 ◽  
Vol 76 (11) ◽  
pp. 1128-1138
Author(s):  
S. R. Rakhmanov
Keyword(s):  
High Frequency ◽  
Deformation Zone ◽  
Pipe Blank ◽  
Equipment Operation ◽  
Metal Deformation ◽  
Technological Tool ◽  
High Frequency Vibrations ◽  
Pipe Blanks ◽  
Wave Phenomena

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

Wordform-specific frequency effects cause acoustic variation in zero-inflected homophones

2020 ◽  
Vol 56 (4) ◽  
pp. 711-739
Author(s):  
Eva Maria Luef ◽  
Jong-Seung Sun
Keyword(s):  
Lexical Access ◽  
High Frequency ◽  
Relative Frequency ◽  
Frequency Effects ◽  
Reduction Processes ◽  
Specific Frequency ◽  
Phonetic Reduction ◽  
Acoustic Variation

Abstract The frequency with which a word appears in the lexicon has implications for its pronunciation. Numerous studies have shown that high-frequency lemma are characterized by more phonetic reduction than lower-frequency lemma. These findings have proven to be particularly useful in the study of homophones where frequency-related reduction processes can give insights into lexical access theories. The majority of research on homophones and frequency effects has focused on heterographic and semantically unrelated homophones (e.g., English time – thyme) or investigated zero-derived homophones (e.g., English the cut, noun – to cut, verb). Here, zero inflection in German pluralization (e.g., ein Würfel ‘one die’– zwei Würfel ‘two dice’) was investigated to determine if and how frequency effects impact on the acoustic realization of the homophonous singular-plural word pairs. The findings indicate that the number-specified wordforms show acoustic variation related to wordform frequency and the relative frequency of the singular to plural inflected forms. Results differ for durations of wordforms, stem vowels, and final phonemes. Our findings have implications for lexical access theories and can inform about ‘frequency inheritance’ across the singular and plural homophones of the zero-inflected plurals.

Analytical Solution for Rotational Rub-Impact Plate Under Thermal Shock

2016 ◽  
Vol 32 (3) ◽  
pp. 297-311
Author(s):  
T.-Y. Zhao ◽  
H.-Q. Yuan ◽  
B.-B. Li ◽  
Z.-J. Li ◽  
L.-M. Liu
Keyword(s):  
Thermal Shock ◽  
High Frequency ◽  
Equations Of Motion ◽  
Low Frequency ◽  
Cantilever Plate ◽  
Analysis Method ◽  
Multiple Frequency ◽  
Width Direction ◽  
Blade Tip ◽  
High Frequency Vibrations

AbstractThe analysis method is developed to obtain dynamic characteristics of the rotating cantilever plate with thermal shock and tip-rub. Based on the variational principle, equations of motion are derived considering the differences between rubbing forces in the width direction of the plate. The transverse deformation is decomposed into quasi-static deformation of the cantilever plate with thermal shock and dynamic deformation of the rubbing plate under thermal shock. Then deformations are obtained through the calculation of modal characteristics of rotating cantilever plate and temperature distribution function. Special attention is paid to the influence of tip-rub and thermal shock on the plate. The results show that tip-rub has the characteristics of multiple frequency vibrations, and high frequency vibrations are significant. On the contrary, thermal shock shows the low frequency vibrations. The thermal shock makes the rubbing plate gradually change into low frequency vibrations. Because rub-induced vibrations are more complicated than those caused by thermal shock, tip-rub is easier to result in the destruction of the blade. The increasing friction coefficient intensifies vibrations of the rubbing plate. Minimizing friction coefficients can be an effective way to reduce rub-induced damage through reducing the surface roughness between the blade tip and the inner surface of the casing.

Convection of a binary mixture under high-frequency vibrations

2013 ◽  
Vol 341 (4-5) ◽  
pp. 477-482 ◽  
Author(s):  
Sergey M. Ishutov ◽  
Bela I. Myznikova ◽  
Boris L. Smorodin
Keyword(s):  
Binary Mixture ◽  
High Frequency ◽  
High Frequency Vibrations

scholarly journals Erratum to: Acute and cumulative effects of focused high-frequency vibrations on the endocrine system and muscle strength

2013 ◽  
Vol 113 (11) ◽  
pp. 2871-2871 ◽  
Author(s):  
Pierpaolo Iodice ◽  
Rosa Grazia Bellomo ◽  
Glaugo Gialluca ◽  
Giorgio Fanò ◽  
Raoul Saggini
Keyword(s):  
Muscle Strength ◽  
High Frequency ◽  
Endocrine System ◽  
Cumulative Effects ◽  
High Frequency Vibrations

Experimental support for the flowing aether concept of gravity

2021 ◽  
Vol 34 (4) ◽  
pp. 538-547
Author(s):  
Duncan W. Shaw
Keyword(s):  
Present Article ◽  
High Frequency ◽  
Experimental Support ◽  
High Frequency Vibrations ◽  
Two Sides

The article of Apffel et al. [Nature 585, 48 (2020)] reported on an experiment that produced the sight of two miniature sailboats floating upside down to each other on the two sides of a layer of glycerol that was levitated by high frequency vibrations. The vessel on the underside of the glycerol is a remarkable display of the results of simulated gravity caused by vibrations. The present article considers this and other experiments on simulated gravity and finds that they provide support for the flowing aether concept of the cause of gravity.

Ultrasonic Cutting of Switchgrass and Miscanthus Stems

2018 ◽  
Vol 34 (2) ◽  
pp. 343-353
Author(s):  
A. Bulent Koc Koc ◽  
Bo Liu
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
High Frequency ◽  
Cutting Speed ◽  
Particle Size Reduction ◽  
Element Analysis ◽  
Cutting Energy ◽  
High Frequency Vibrations ◽  
Ultrasound Assisted ◽  
Ultrasonic Cutting

Abstract. Ultrasound-assisted cutting has been used to cut materials with high precision, improved quality and reduced cutting forces. The research objective was to investigate the effects of high-frequency vibrations on the cutting force and cutting energy of switchgrass and miscanthus stems. Laboratory experiments were conducted on individual biomass stems at cutting speeds between 3 and 400 mm/s. An experimental cutting system with an ultrasound generator, an ultrasonic blade, a load cell, and a data acquisition system was developed. The custom designed blade was 5-cm wide and vibrated at 19.551 kHz with 2.8 µm tip vibration amplitude. There were significant measured differences in the cutting forces and cutting energies between conventional cutting and ultrasonic cutting of switchgrass and miscanthus stems (p < 0.05). These results suggest that the use of high-frequency vibrations reduce cutting force and cutting energy of both switchgrass and miscanthus stems. Ultrasound-assisted cutting reduced the cutting energy of switchgrass by 66.85% at 100 mm/s and miscanthus by 80.58% at 30 mm/s. However, ultrasonic cutting did not have a significant effect on the cutting force and cutting energy when the cutting speed was equal to or greater than the blade tip vibration speed. The results of this research should be useful for adapting the ultrasonic technology in biomass harvesting, particle size reduction, and processing equipment. Keywords: Biomass, Blades, Energy, Finite element analysis, Miscanthus, Switchgrass, Ultrasonics.

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