scholarly journals PILOT STUDIES OF PROCESS OF VIBROACOUSTIC DYNAMICS AT LOCAL HARDENING OF DETAILS A SHARIKO-ROD UPROCHNITEL

2019 ◽  
Vol 45 (4) ◽  
pp. 52-58
Author(s):  
S. A. Morozov ◽  
A. N. Chukarin
Keyword(s):  
High Frequency ◽  
Metal Cutting ◽  
Research Work ◽  
Sound Field ◽  
World Market ◽  
Spectral Structure ◽  
Noise Levels ◽  
Acoustic Characteristics ◽  
Pilot Studies ◽  
Working Zone

Objectives The most important problem of modern mechanical engineering is increase in durability of products, their efficiency and competitiveness in the world market. The equipment for machining creates the increased noise levels in a working zone of operators. Now regularities of formation of acoustic characteristics are studied generally for metal-cutting and woodworking machines of various types. Formation of the sound field at shariko-rod hardening is studied insufficiently. The purpose of researches which results are given in this article consisted in studying of regularities of spectral structure of noise and vibrations when processing ShSU of details with various ways of fixing. Method. In the course of pilot studies the known methods of measurement and processing of experimental data in relation to acoustic and vibration characteristics were used. Results. It is established that noise ranges at ShSU of details with various ways of fixing have identical regularities of a shumoobrazovaniye and are characterized by pronounced high-frequency character. It is proved that the dominating sources yaa-lyatsya the strengthened detail and an uprochnitel. Conclusion. Sizes of excesses of levels of sound pressure systems "up-rochnitel-detal2 in a high-frequency part of a range 500-8000gts are installed. The established regularities of formation of spectral structure are a basis for the choice of means of decrease in noise levels. Work is performed within initiative research work.

Design and Construction of a Small Reverberation Chamber Applied to Absorption and Scattering Acoustic Measurements

2014 ◽  
Vol 1077 ◽  
pp. 197-202
Author(s):  
D. Hernandez ◽  
E.J. Liu ◽  
J.H. Huang ◽  
Y.C. Liu
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Sound Field ◽  
Acoustic Measurements ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Scattering Coefficients ◽  
Reverberation Chambers ◽  
The Cost ◽  
Design And Construction

Reverberation chambers are used to create a diffuse incidence sound field, where multiple types of acoustic measurements can be performed. The chambers tend to have a large volume in order to extent the reverberation time. However, this requirement may be conditioned by the cost and the infrastructure limitations. This paper presents the design and construction of a small-scaled reverberation chamber of 3 m3 for middle-high frequency acoustic measurements. On the design, the acoustic characteristics of chamber are confirmed via finite element computer simulation. As case studies, absorption and scattering coefficients of several materials and diffusors are measured. The reverberation times needed for the measurements were obtained by the impulse response integration method. The small reverberation chamber demonstrated to be a reliable tool for middle and high frequency acoustic measurements.

Prediction and analysis of sound field in long enclosures with a modal-based method

2021 ◽  
Vol 69 (6) ◽  
pp. 518-529
Author(s):  
Changyong Jiang ◽  
Xiang Liu ◽  
Stephany Y. Xu ◽  
Shangyu Zhang
Keyword(s):  
Porous Material ◽  
Point Source ◽  
Sound Pressure Level ◽  
High Frequency ◽  
Sound Pressure ◽  
Prediction Method ◽  
Sound Field ◽  
Pressure Level ◽  
Noise Levels ◽  
Level Reduction

In this paper, the efficacy of porous ceiling treatment to reduce noise levels inside a typical tunnel is examined with a validated modal-based prediction method. It is found that, for a point source, the effect of increasing porous ceiling thickness on sound pressure level (SPL) attenuation along the tunnel is limited. A porous ceiling with thickness of 0.3 m is comparable with an infinite porous ceiling in middle and high frequency ranges. For a line source, the effect of ceiling thickness on SPL reduc- tion in this typical tunnel is limited. Sound pressure level reduction of 4 dBA is real- ized with 0.3 m porous ceiling, which is the same as infinite ceiling and only 1 dBA smaller than the theoretically optimized value. These results suggest that, in the event only ceiling treatment is considered, 0.3 m porous material is sufficient for noise re- duction in this typical tunnel.

Modified Earpieces and CROS for High Frequency Hearing Losses

1968 ◽  
Vol 11 (1) ◽  
pp. 204-218 ◽  
Author(s):  
Elizabeth Dodds ◽  
Earl Harford
Keyword(s):  
Hearing Loss ◽  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Sound Field ◽  
Intensity Level ◽  
Test Results ◽  
High Frequency Hearing Loss ◽  
Increased Sensitivity ◽  
Difficult Cases

Persons with a high frequency hearing loss are difficult cases for whom to find suitable amplification. We have experienced some success with this problem in our Hearing Clinics using a specially designed earmold with a hearing aid. Thirty-five cases with high frequency hearing losses were selected from our clinical files for analysis of test results using standard, vented, and open earpieces. A statistical analysis of test results revealed that PB scores in sound field, using an average conversational intensity level (70 dB SPL), were enhanced when utilizing any one of the three earmolds. This result was due undoubtedly to increased sensitivity provided by the hearing aid. Only the open earmold used with a CROS hearing aid resulted in a significant improvement in discrimination when compared with the group’s unaided PB score under earphones or when comparing inter-earmold scores. These findings suggest that the inclusion of the open earmold with a CROS aid in the audiologist’s armamentarium should increase his flexibility in selecting hearing aids for persons with a high frequency hearing loss.

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.

Study on acoustic and flow-induced noise characteristics of L-shaped duct with a shallow cavity

2020 ◽  
Vol 68 (3) ◽  
pp. 209-225
Author(s):  
Masaaki Mori ◽  
Kunihiko Ishihara
Keyword(s):  
Air Conditioning ◽  
Sound Field ◽  
Frequency Range ◽  
Acoustic Characteristics ◽  
Inflow Velocity ◽  
Aerodynamic Sound ◽  
Noise Characteristics ◽  
Flow Induced Noise ◽  
Shallow Cavity ◽  
Conditioning Equipment

An aerodynamic sound generated by a flow inside a duct is one of the noise pro- blems. Flows in ducts with uneven surfaces such as grooves or cavities can be seen in various industrial devices and industrial products such as air-conditioning equipment in various plants or piping products. In this article, we have performed experiments and simulations to clarify acoustic and flow-induced sound characteris- tics of L-shaped duct with a shallow cavity installed. The experiments and simula- tions were performed under several inflow velocity conditions. The results show that the characteristics of the flow-induced sound in the duct are strongly affected by the acoustic characteristics of the duct interior sound field and the location of the shallow cavity. Especially, it was found that the acoustic characteristics were af- fected by the location of the shallow cavity in the frequency range between 1000 Hz and 1700 Hz.

Experiment Study of Oil-Air Lubrication on Cooling of Turning Tools

2011 ◽  
Vol 189-193 ◽  
pp. 3187-3190 ◽  
Author(s):  
Jin Li Wang ◽  
Lin Cai ◽  
Hong Tao Zheng
Keyword(s):  
Metal Cutting ◽  
Research Work ◽  
Cutting Temperature ◽  
Cost Savings ◽  
Machining Process ◽  
Dry Cutting ◽  
Air Lubrication ◽  
Temperature Contrast ◽  
Cooling Technology ◽  
Lubrication Conditions

When lubricants are used according to special requirements, it is possible to achieve considerable cost savings. Compared to conventional coolant cooling technology used in metal cutting, oil-air lubrication increases cooling performance, avoids environmental pollution, reduces running and maintenance costs. The cutting temperature contrast experimental research was based on close to practice 45# steel in dry cutting, wet cutting and oil-air lubrication conditions. The research work concentrated on the superiority of oil-air lubrication cooling and the influence of cutting amount on temperature. The experimental results show that oil-air lubrication is more effective in reducing the cutting temperature than wet cutting or dry cutting, this paper details the cutting temperature curves at several different tests provides a basis for industrial production, improves the level of machining process and the significance was being reported.

Effective splicing localization based on noise level inconsistencies

2021 ◽  
pp. 1-11
Author(s):  
P. N. R. L. Chandra Sekhar Author ◽  
T. N. Shankar Author
Keyword(s):  
Digital Technology ◽  
Social Networking Sites ◽  
Noise Level ◽  
Research Work ◽  
Multimedia Content ◽  
Noise Levels ◽  
Multimedia Forensics ◽  
The Past ◽  
Photo Editing ◽  
State Of Art

In the era of digital technology, it becomes easy to share photographs and videos using smartphones and social networking sites to their loved ones. On the other hand, many photo editing tools evolved to make it effortless to alter multimedia content. It makes people accustomed to modifying their photographs or videos either for fun or extracting attention from others. This altering brings a questionable validity and integrity to the kind of multimedia content shared over the internet when used as evidence in Journalism and Court of Law. In multimedia forensics, intense research work is underway over the past two decades to bring trustworthiness to the multimedia content. This paper proposes an efficient way of identifying the manipulated region based on Noise Level inconsistencies of spliced mage. The spliced image segmented into irregular objects and extracts the noise features in both pixel and residual domains. The manipulated region is then exposed based on the cosine similarity of noise levels among pairs of individual objects. The experimental results reveal the effectiveness of the proposed method over other state-of-art methods.

scholarly journals EFFICIENT ACOUSTIC COMPOSITE PANELS BASED ON GRAPHITE

2021 ◽  
Vol 6 (4) ◽  
pp. 82-90
Author(s):  
E. Fanina
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Sound Field ◽  
Fire Retardant ◽  
Pyramidal Cells ◽  
Sound Insulation ◽  
Composite Panels ◽  
Thin Membrane ◽  
Reverberation Time ◽  
Acoustic Characteristics

A set of experimental studies is carried out to determine the acoustic characteristics of three-dimensional panels of fixed thickness made of carbon-based composite material installed in the opening between the reverberation chambers. Sound insulation indices are determined when they are excited by a diffuse sound field in wide frequency ranges. The reverberation time in model chambers with different partition configurations is calculated. The optimal configuration of the partition with pyramidal cells to reduce the reverberation time in the rooms is determined. The use of graphite in the form of thin membrane applied to various surfaces can significantly reduce the sound pressure levels in the room and increase the sound insulation indices of air noise. In addition to thin membrane, graphite can be used as an additive in composite materials for sound insulation purposes. It is shown that the characteristics of such panels are quite universal. The measured acoustic characteristics of composite panels are compared with similar characteristics of traditional materials. It is determined that the composition belongs to the I group of fire-retardant efficiency and can be recommended for use as a fire-retardant material. The developed acoustic material is an effective absorbing agent that solves problems in architectural acoustics, echo cancellation in construction and architecture. Similar to metamaterials, natural and artificial graphites allow to solve these problems with small volumes and masses using simple and inexpensive technologies.

Further Observations on Noise Levels in Infant Incubators

PEDIATRICS ◽  
1979 ◽  
Vol 63 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Fred H. Bess ◽  
Barbara Finlayson Peek ◽  
Judy J. Chapman
Keyword(s):  
High Frequency ◽  
Impulse Noise ◽  
Life Support ◽  
Acoustic Analysis ◽  
Frequency Region ◽  
Noise Levels ◽  
Storage Unit ◽  
High Frequency Region ◽  
Different Types ◽  
Opening And Closing

The purpose of this study was to conduct an acoustic analysis of incubator noise under two conditions: when the incubator was associated with different types of life-support equipment; and when impulse noise was created by striking the side of the incubator or by opening and closing the doors of the storage unit. It was found that the life-support equipment increased the overall noise levels of incubators by as much as 15 to 20 dB. Much of this increased energy was in the high frequency region. Impulse signals created by striking the side of the incubator ranged from 130 to 140 dB. A representative impulse for opening the incubator was 92.8 dB, whereas closing the door produced a peak amplitude of 114 dB.

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