The Derivation of the Noise Level Dependences and Vibration Velocities of Elements and Units of the Drive System of the Rail Grinding Machines

Intensive wear of rails in curves significantly reduces their service life, reduces the efficiency of operational work. A promising direction in solving this problem is the technology of rail grinding, which allows mechanical processing of the rail head without dismantling them in the conditions of a railway track. The article presents the results of studies of the noise impact on track workers when grinding rails by means of small mechanization-a rail-grinding machine SH-1, a grinding machine 2152D and a manual machine for grinding rails MRSH3. The analysis of various layouts of rail grinding machines, their features, technical characteristics and octave levels of sound pressure when these machines are running at idle and under load was carried out. According to the results of experimental studies, graphical dependences of the sound pressure levels of rail grinding machines are constructed, the excess of the noise level over the permissible sanitary standards in the area of rail grinding by means of small mechanization is revealed.

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Flour Mill Workers Occupational Noise Exposure in Chandrapur City, Central India

International Journal of Environment ◽

10.3126/ije.v7i1.21290 ◽

2018 ◽

Vol 7 (1) ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Namrata R. Nimgade ◽

R. K. Kamble

Keyword(s):

Noise Level ◽

Noise Exposure ◽

Central India ◽

Sound Level ◽

Shop Floor ◽

Occupational Noise ◽

Noise Levels ◽

Occupational Noise Exposure ◽

Flour Mill ◽

Grinding Machines

Assessment of occupational noise exposure of flour mill workers in Chandrapur city of central India was carried out during November 2015-January 2016. Total 62 flour mills were selected for this study comprising one, two and three grinding machines operating in the shop floor. The sound level meter was used to measure sound level at 50 cm and 3 meters from grinding machines at receiver’s position during operation. Noise monitoring was also recorded when one, two and three machines were operating individually and simultaneously. The results showed that noise levels when one grinding machine in operation in close proximity (50 cm) was in the range of 80-97 dB(A). Comparison of these observations with that of 3 meters distance; it was observed that noise levels got reduced and in the range of 70-77 dB(A). In the case of two machines in operation, it was in the range of 95-118 dB(A) at 50 cm distance and reduced to 75-95 dB(A) at 3 meters distance. This reduction in noise level was due to the propagation of noise in the ambient environment. Furthermore, daily noise exposure points, exposure points job per task and exposure points per hour were computed by using noise exposure calculator developed by Health and Safety Executive (HSE), United Kingdom. The computation from this calculator revealed that these attributes were directly depended upon noise levels in flour mills and duration of noise exposure. A positive linear Pearson’s correlation (p<0.01) was observed between noise level and exposure points per hour. Of the 65 flour mill workers surveyed, 70.76% reported a hearing problem, 23.07% headache at work and out of which 7.69% workers headache remains after completion of work also. Remedial measures to control noise exposure to flour mill workers such as ear plugs, ear muff, semi-insert are recommended.

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Electron Microscopy in Molecular Biology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060027 ◽

1967 ◽

Vol 25 ◽

pp. 2-3

Author(s):

Cecil E. Hall

Keyword(s):

Electron Microscopy ◽

Molecular Biology ◽

Noise Level ◽

Molecular Structures ◽

Material Structure ◽

The Arts ◽

Shadow Casting ◽

Electron Image ◽

High Degree ◽

Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

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Detection of a point defect in a silicon single crystal by high-resolution TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138701 ◽

1995 ◽

Vol 53 ◽

pp. 466-467

Author(s):

M. Awaji

Keyword(s):

High Resolution ◽

Single Crystal ◽

Point Defect ◽

Point Defects ◽

Noise Level ◽

Dark Field ◽

Silicon Single Crystal ◽

High Resolution Image ◽

Dark Field Imaging ◽

Field Imaging

It is necessary to improve the resolution, brightness and signal-to-noise ratio(s/n) for the detection and identification of point defects in crystals. In order to observe point defects, multi-beam dark-field imaging is one of the useful methods. Though this method can improve resolution and brightness compared with dark-field imaging by diffuse scattering, the problem of s/n still exists. In order to improve the exposure time due to the low intensity of the dark-field image and the low resolution, we discuss in this paper the bright-field high-resolution image and the corresponding subtracted image with reference to a changing noise level, and examine the possibility for in-situ observation, identification and detection of the movement of a point defect produced in the early stage of damage process by high energy electron bombardment.The high-resolution image contrast of a silicon single crystal in the [10] orientation containing a triple divacancy cluster is calculated using the Cowley-Moodie dynamical theory and for a changing gaussian noise level. This divacancy model was deduced from experimental results obtained by electron spin resonance. The calculation condition was for the lMeV Berkeley ARM operated at 800KeV.

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Evaluation of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings by the multi-frequency radio wave method of a slow surface electromagnetic waves

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-8-51-58 ◽

2020 ◽

pp. 51-58

Author(s):

Aleksandr I. Kazmin ◽

Pavel A. Fedjunin

Keyword(s):

Radio Wave ◽

Noise Level ◽

Electromagnetic Waves ◽

Dielectric Materials ◽

Geometric Parameters ◽

Experimental Investigations ◽

Wave Method ◽

Dielectric Coatings ◽

Surface Electromagnetic Waves ◽

Multilayer Dielectric

One of the most important diagnostic problems multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the checkout results their electrophysical and geometric parameters. The results of a study of the potential informativeness of the multi-frequency radio wave method of surface electromagnetic waves during reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings are presented. The simulation model is presented that makes it possible to evaluate of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings. The model takes into account the values of the electrophysical and geometric parameters of the coating, the noise level in the measurement data and the measurement bandwidth. The results of simulation and experimental investigations of reconstruction of the structure of relative permittivitties and thicknesses of single-layer and double-layer dielectric coatings with different thicknesses, with different values of the standard deviation (RMS) of the noise level in the measured attenuation coefficients of the surface slow electromagnetic wave are presented. Coatings based on the following materials were investigated: polymethyl methacrylate, F-4D PTFE, RO3010. The accuracy of reconstruction of the electrophysical parameters of the layers decreases with an increase in the number of evaluated parameters and an increase in the noise level. The accuracy of the estimates of the electrophysical parameters of the layers also decreases with a decrease in their relative permittivity and thickness. The results of experimental studies confirm the adequacy of the developed simulation model. The presented model allows for a specific measuring complex that implements the multi-frequency radio wave method of surface electromagnetic waves, to quantify the potential possibilities for the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric materials and coatings. Experimental investigations and simulation results of a multilayer dielectric coating demonstrated the theoretical capabilities gained relative error permittivity and thickness of the individual layers with relative error not greater than 10 %, with a measurement bandwidth of 1 GHz and RMS of noise level 0,003–0,004.

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AN IMPROVED ARMORED VEHICLE KRAZ “FIONA” NOISE SILENCER

Avtoshliakhovyk Ukrayiny ◽

10.33868/0365-8392-2019-1-257-21-26 ◽

2019 ◽

pp. 21-26

Author(s):

Volodymyr Fedorov ◽

Vasyl’ Yanovsky ◽

Dmytro Kovalshuk

Keyword(s):

Noise Reduction ◽

Speed Of Sound ◽

Acoustic Waves ◽

Noise Level ◽

Combustion Engine ◽

Environmental Aspect ◽

Exhaust Gases ◽

Ecological Requirements ◽

On The Road ◽

Armored Vehicle

Ecological requirements for cars grow from year to year, both in the world as a whole, and in Ukraine in particular. This is especially true of noise pollution. Additionally, noise reduction becomes relevant, taking into account the conduct of military operations during the last 5 years on the territory of Ukraine. The war has caused a special need for military vehicles for which masking properties are vital. Noise is a serious disincentive factor. Therefore, its reduction for a military vehicle, apart from the environmental aspect, is of a purely military nature, that is, it is extremely important. The car has many sources of noise there are many ways to deal with them. One of the most powerful source of noise is the sleeping bag. This kind of noise is reduced by means of silencers of noise. The vast majority of silencer data in the basis of its design has a reactive (or resonant) muffler. To calculate the jet silencer you must know the speed of sound in the sleeping bags. In order to increase the acoustic efficiency of reactive and resonant mufflers of exhaust gases noise of the ICE of cars, an experimental method was proposed for determining the speed of sound in the sleighs. Implementation of the method is carried out by measuring the attenuation of acoustic waves. The noise level of the bedrooms is measured without silencer and silencer. Based on the data obtained, the noise reduction performance of the residual is established. From the well-known formula, based on the calculation of the efficiency of the silencing of a jet muffler, a formula is obtained for calculating the speed of sound in the sleeping quays. In this formula, all parameters are known: the level of silencer efficiency, the noise level of the sleeping, the ratio of areas of cross sections of the muffler and the inlet pipe and the length of the muffler. The sound speed thus established can continue to be used not only for engines of the type for which measurements and calculations were made, but also with a certain approximation for some other types of engines. This method provides high accuracy for determining the required parameter. In the given work on the example of the armored car KrAZ “Fiona” the calculation of efficiency increase of the reactive silencer is made due to the above-mentioned method. Also, the projected decrease in the external noise level of the KrAZ Armored Vehicle “Fiona” is considered by determining the speed of sound in the recesses on the trunk cycle on the road with acceleration up to speed of 50 km/h (75 km/h) and the movement with this speed, as well as when driving at a speed of 45 km/h. Keywords: transport, armored car, internal combustion engine, exhaust, exhaust gases, noise, source, acoustic efficiency, acoustic efficiency, speed of sound, jet muffler.

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