Determination of the noise attenuation of hearing protectors by numerical modeling of the outer ear

1998 ◽  
Vol 103 (5) ◽  
pp. 3004-3004
Author(s):  
Samir N. V. Gerges ◽  
Elizabete Y. Bavastri
Keyword(s):  
Numerical Modeling ◽  
Noise Attenuation ◽  
Hearing Protectors

scholarly journals Attenuation of earmuffs used simultaneously with safety spectacles in exposure to impulse noise

2018 ◽  
Vol 67 (1) ◽  
pp. 43-53
Author(s):  
Emil Kozłowski ◽  
Rafał Młyński
Keyword(s):  
Impulse Noise ◽  
Rectangular Cross Section ◽  
Real Life ◽  
Sound Attenuation ◽  
Protective Measure ◽  
Noise Attenuation ◽  
Impact Noise ◽  
Hearing Protectors ◽  
Simultaneous Use

Impulse noise is particularly hazardous to the hearing of exposed individuals. In many real-life scenarios, the only protective measure used to reduce the level of impulse noise is hearing protectors. These scenarios include firing ranges. Aside from hearing protectors, shooters use personal safety spectacles. The purpose of this paper was to determine the effect of the simultaneous use of earmuffs and safety spectacles on the sound attenuation of earmuffs during exposure to impact noise. The research was completed with the MIRE method and included the determination of sound attenuation changes in five different models of earmuffs, used simultaneously with three different models of safety spectacles and prescription glasses. The impulse noise source used was a starting pistol, which generated C-weighted peak sound pressure level at a mean of 136.7 dB. The tests demonstrated that the simultaneous use of safety spectacles and earmuffs reduces the impulse noise attenuation of the earmuffs by up to 9 dB. Such sound attenuation changes occurred during simultaneous use of earmuffs with safety spectacles, which feature temples with a rectangular cross-section. The tests also demonstrated that the effect of prescription glasses on sound attenuation was unusually high; prescription glasses reduced the impulse sound attenuation of earmuffs by as much as 18 dB. Keywords: acoustics, noise protection, impulse noise, hearing protectors, earmuffs, noise attenuation

scholarly journals Numerical Modeling of the Degradation of the Normal Stress Under Large Number of Shearcycles

2021 ◽  
Vol 31 (3) ◽  
pp. 118-133
Author(s):  
Assia Bellayoune ◽  
Salah Messast ◽  
Marc Boulon
Keyword(s):  
Numerical Modeling ◽  
Normal Stress ◽  
Horizontal Stress ◽  
Cyclic Stress ◽  
Simple Expression ◽  
Shear Tests ◽  
Cyclic Shear ◽  
Explicit Formulation ◽  
Number Of Cycles

Abstract The evaluation of friction is an important element in the verification of stability and the determination of the bearing capacity of piles. In the case of cyclic stress, the soil-pile interface has a relaxation which corresponds to a fall in the horizontal stress which represents the normal stress at the lateral surface of the pile. This paper presents an explicit formulation to express the degradation of the normal stress after a large number of shear cycles as a function of cyclic parameters. In this study we are interested in the exploitation of the cyclic shear tests carried out by Pra-ai [1] with imposed normal rigidity (CNS) in order to demonstrate the phenomenon of falling of the normal stress. The approach presented in this paper consists in proposing a simple expression for estimating the degradation of normal stress as a function of cyclic shear parameters after a large number of cycles. The validation of this approach is verified by the application of this formulation to a real case where the comparison of the simulations made by this approach with those recorded on site shows the good adaptation of this approach to this type of problems.

NEW METHOD OF IMPULSIVE ELECTROMAGNETIC LOGGING SOUNDING: MAPPING OF THE BAZHENOVSKAYA FORMATION FROM JURASSIC RESERVOIRS PENETRATED BY INCLINED-HORIZONTAL WELLS

2021 ◽  
pp. 31-39
Author(s):  
M. I. Epov ◽  
◽  
V. N. Glinskikh ◽  
M. N. Nikitenko ◽  
K. V. Sukhorukova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Modeling ◽  
Middle Jurassic ◽  
High Sensitivity ◽  
Horizontal Wells ◽  
New Method ◽  
Electromagnetic Sounding ◽  
Bazhenov Formation ◽  
Spatial Locations

The work is devoted to the substantiation of new geophysical technology for mapping the Bazhenovskaya Formation based on an impulsive electromagnetic sounding from wells. Theoretically shown the possibility of its application to study the formation from highly inclined and subhorizontal wells drilled in the Upper and Middle Jurassic formations. Numerical modeling of the signals in realistic geoelectric models of the Bazhenov Formation with real well trajectories is carried out on the example of the East Surgut field. The calculations have established that the determination of spatial locations of the top and bottom of the beds is possible when using different-length sondes. Zones of high sensitivity of the full magnetic field matrix to the boundaries with a sufficient signal level at considerable distance, even with a small sonde length, are determined. It is theoretically established that pulsed sounding of the Bazhenov Formation from the Upper and Middle Jurassic reservoirs is feasible for both mapping the boundaries of the formation and tracing its lateral variability.

scholarly journals Determination of pressure in the near-ground space pile terminated and broadening of the surface

2018 ◽  
Vol 251 ◽  
pp. 04062
Author(s):  
Natalia Kupchikova
Keyword(s):  
Numerical Modeling ◽  
Circular Cross Section ◽  
Analytical Form ◽  
Soil Mass ◽  
Software Systems ◽  
Discrete Method ◽  
Building Foundation ◽  
Geological Conditions ◽  
Complex Engineering

The article deals with the problem of determining the stress state of a complex pile structure with end broadening in the form of a sphere in the soil mass in the analytical form by a discrete method. The calculation schemes for determining the stress tensor at the boundary of the pile of square and circular cross-section with expansions in the soil massif are shown. The elements of the polynomial are found by the discrete method in rectangular and spherical coordinates, which is a cumbersome complex mathematical apparatus for a modern design engineer. The stresses are determined. At present, as the analysis has shown, the solution of complex geotechnical problems of soil bases and foundations for different types of loads in numerical modeling is carried out using modern software. Numerical modeling and calculation with the help of specialized software systems allows to consider the system “building-foundation-ground foundation”, as dynamic, integrally developing. However, the interaction of the components of this system requires a theoretical justification of the resistance of foundations in the ground environment, especially in complex engineering-geological conditions.

Technical Notes. Earmuff Noise Leakage Measurements and Evaluation

2015 ◽  
Vol 40 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Samir N.Y. Gerges ◽  
Rafael N.C. Gerges ◽  
Roberto A. Dias
Keyword(s):  
Contact Area ◽  
Flat Surface ◽  
Low Cost ◽  
Human Head ◽  
Noise Attenuation ◽  
High Quality ◽  
Quantitative Effect ◽  
Hearing Protectors

Abstract This paper reports the quantitative effect of leakage on the noise attenuation of earmuff hearing protectors. The technology used in this study to measure the noise leakage is considered to be a new contribution to this topic. An array of sensors placed between an earmuff and a dummy human head or flat surface was used to measure the contact area. Areas of no contact are considered as the leakage elements. Eight earmuffs varying from high quality/high cost to low quality/low cost were tested, the leakage areas were measured and the reduction in the noise attenuation due to leakage was calculated

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