DETERMINATION OF THE INFLUENCE OF STRUCTURAL ELEMENTS ON ACOUSTIC EFFICIENCY AND BACK PRESSURE IN EXHAUST AND SUCTION NOISE SILENCERS

Akustika ◽  
2021 ◽  
pp. 210-216
Author(s):  
Nickolay Ivanov ◽  
Aleksandr Shashurin ◽  
Aleksandr Burakov
Keyword(s):  
Structural Design ◽  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Back Pressure ◽  
Noise Generation ◽  
Structural Elements ◽  
The Relationship

The features of noise generation processes in exhaust and suction noise silencers are shown. A method for testing silencers has been developed. The classification of the main structural elements of exhaust and suction noise silencers, depending on the purpose, is proposed. Experimental studies of the relationship between the acoustic efficiency and the back pressure of silencers from the structural design of the elements are performed. The factors influencing the efficiency in the low-frequency and high-frequency regions of the spectrum are determined: the volume of silencers, the number of chambers, perforation, sound absorption, flow ejection, etc. Recommendations for the design of noise silencers are proposed.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

scholarly journals Calculation improvement of no-load stray losses in induction motors with experimental validation

2015 ◽  
Vol 12 (3) ◽  
pp. 303-320
Author(s):  
Miloje Kostic
Keyword(s):  
High Frequency ◽  
Experimental Validation ◽  
Air Gap ◽  
New Classification ◽  
Iron Losses ◽  
Surface Iron ◽  
Space Harmonics ◽  
Rotor Cage

On the basis of the known fact that all air gap main flux density variations are enclosed by permeance slot harmonics, only one component of stray losses in rotor (stator) iron is considered in the new classification, instead of 2 components: rotor (stator) pulsation iron losses, and rotor (stator) surface iron losses. No-load rotor cage (high-frequency) stray losses are usually calculated. No-load stray losses are caused by the existence of space harmonics: the air-gap slot permeance harmonics and the harmonics produced by no-load MMF harmonics. The second result is the proof that the corresponding components of stray losses can be calculated separately for the mentioned kind of harmonics. Determination of the depth of flux penetration and calculations of high frequency iron losses are improved. On the basis of experimental validation, it is proved that the new classification of no-load stray losses and the proposed method for the calculation of the total value is sufficiently accurate.

Role of Dominance Status in Shock-Stimulated Agonistic Behavior

1971 ◽  
Vol 29 (3) ◽  
pp. 768-770 ◽  
Author(s):  
G. McA. Kimbrell ◽  
D. Chesler
Keyword(s):  
High Frequency ◽  
Agonistic Behavior ◽  
Defensive Behavior ◽  
Low Frequency ◽  
Behavior Patterns ◽  
Dominance Status ◽  
Very Low Frequency ◽  
The Relationship ◽  
Shock Situation

To clarify the relationship between dominance status and frequency of specific sub-classes of agonistic behavior in response to foot shock, 30 mice were selected on the basis of high- or low-dominance status and paired in a foot-shock situation. Dominant pairs exhibit a high frequency of defensive behavior patterns whereas submissive pairs exhibit a very low frequency of defensive patterns.

Dynamic relation between global Islamic and conventional sectoral stock and bonds indexes

2020 ◽  
Vol 07 (02) ◽  
pp. 2050006
Author(s):  
Sukriye Tuysuz
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Stock Index ◽  
High Frequency Part ◽  
Dynamic Relation ◽  
The Relationship

This paper examines the relationship between 10 Global sectoral conventional and Islamic assets. For each sector, a conventional, an Islamic stock index and a bond are retained. The analyzed relations are done by taking into account diverse investment horizons by using MODWT and GARCH-DCC-type models. Our results indicate that adding bond indexes into a portfolio composed with conventional stock or Islamic stock is efficient. As for the correlations between conventional and Islamic sectoral indexes, they depend on the sector. Relations between returns of securities are quite similar to the relations between high-frequency part of these series and are very volatile at low frequency.

Reliance on Visual Imagery and its Relation to Mental Rotation

1997 ◽  
Vol 85 (2) ◽  
pp. 431-434 ◽  
Author(s):  
Doris C. Weatherly ◽  
Steven E. Ball ◽  
James R. Stacks
Keyword(s):  
Mental Rotation ◽  
Response Latency ◽  
High Frequency ◽  
Visual Imagery ◽  
Learning Effect ◽  
Low Frequency ◽  
Computer Screen ◽  
The Right ◽  
Relationship Of ◽  
The Relationship

The relationship of habitual use of visual imagery and mental rotation was investigated. Reliance on Visual Imagery scores were used to define subjects as high frequency or low frequency visualizers. During the mental rotation task, subjects indicated if a pair of 2-dimensional stimulus figures displayed on a computer screen were identical or mirror-images. Figures on the right were rotated in relation to those on the left by 0, 60, 120, or 180°. Data supported the prediction that subjects who report high use of imagery would perform the task with greater accuracy ( z=1.97, p<.05) than subjects who reported low use. The imagery groups did not differ in response latency ( z = .91, p<.36). A comparison of performance on Trials 1 to 24 with performance on Trials 115-138 indicated a learning effect in both accuracy ( z = 7.58, p<.01) and latency ( z = 9.72, p<.01) for all subjects.

Feature Analysis of Mechanical Fault Signals Based on the Wavelet Transform Technique

2010 ◽  
Vol 139-141 ◽  
pp. 2502-2505
Author(s):  
Bing Cheng Wang ◽  
Zhao Hui Ren
Keyword(s):  
High Frequency ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
Feature Analysis ◽  
Oil Whip ◽  
Frequency Components ◽  
Quantitative Manner ◽  
Beat Phenomenon ◽  
The Impact ◽  
The Relationship

Simulated four different fault signals in the lab, the authors then used wavelet scalogram and amplitude spectrum to make analysis on the above four fault signals and abstract each spectrum characteristics. Wavelet scalogram was able to extract the characteristic’s frequency, show the impact components caused by rub-impact, show the beat phenomenon caused by oil whip and show the irreducible high frequency components as well as the complex low-frequency components. Amplitude spectrum was able to show the energy size distribution at various frequency bands and able to analyze and calculate the relationship between various frequency components. Thus they express the relationship between various frequency banks from a quantitative manner. Therefore, combining the wavelet scalogram and amplitude spectrum when making analysis, as they complement and verify each other, it will enhance the reliability when extract and analyze the characteristics of fault signal.

Effect of Auricular Acupuncture on Gastrointestinal Motility and Its Relationship with Vagal Activity

2013 ◽  
Vol 31 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Han Li ◽  
Yin-Ping Wang
Keyword(s):  
Vagus Nerve ◽  
High Frequency ◽  
Low Frequency ◽  
Autonomic Nerve ◽  
Auricular Acupuncture ◽  
Vagal Activity ◽  
Nerve Function ◽  
Gi Transit ◽  
The Relationship ◽  
Gi Motility

Background Vagus nerve stimulation is capable of regulating autonomic nerve function. In Traditional Chinese Medicine, the effect of auricular acupuncture (AA) is mediated by the vagus. This study was designed to investigate the effect of AA on gastrointestinal (GI) motility and the relationship of this effect with the vagus nerve. Methods 50 rats were divided into five groups for observation of the effects of different types of acupuncture and influencing factors: control, AA, somatic acupuncture (SA), atropine and atropine+AA. The acupuncture points used for AA were ST (Stomach) and SI (Small intestine), while the acupuncture point used for SA was ST36. Electroacupuncture was performed for 15 min. A model of reduced GI motility was established using ethanol, and GI transit rate was used to measure GI motility. Heart rate variability (HRV) and the effect of atropine administration were investigated to study the relationship between AA and vagal activity. Results The GI transit rate increased in both the AA and SA groups compared with control, and no significant difference was found between their effects. In addition, after atropine administration, AA was found to be ineffective in influencing the GI transit rate. In the HRV analysis, no significant differences were found in the absolute low frequency normalised units, high frequency normalised units or the low frequency/high frequency component ratio in the AA or SA groups compared with control. After administration of atropine AA still had no effect on HRV. Conclusions The function of AA in improving GI motility is similar to that of SA, and this effect can be blocked by the presence of atropine, indicating that this effect is regulated by the vagus. However, HRV did not reflect the acupuncture-induced changes in vagal nerve function.

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