Adaptive EMG noise reduction in ECG signals using noise level approximation

2017 ◽  
Author(s):  
Mohamed Marouf ◽  
Lazar Saranovac
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Ecg Signals

AN IMPROVED ARMORED VEHICLE KRAZ “FIONA” NOISE SILENCER

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.

Noise Reduction in ECG Signals Using Notch Filter

2017 ◽  
Vol 5 (8) ◽  
pp. 147-150
Author(s):  
Chhavi Saxena ◽  
Hemant Kumar Gupta ◽  
P.D. Murarka
Keyword(s):  
Noise Reduction ◽  
Notch Filter ◽  
Ecg Signals

Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part

2021 ◽  
Vol 263 (4) ◽  
pp. 2930-2939
Author(s):  
Byungchae Kim ◽  
Hyunjin Kim ◽  
Wonuk Kang
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Measurement Method ◽  
Road Traffic ◽  
Low Noise ◽  
Management Standards ◽  
Close Proximity ◽  
Porous Pavement ◽  
Reduction Effect ◽  
Measurement Location

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

Excess noise reduction with ear protector applying mathematical algorithm: A case of medium density fiber industry

2020 ◽  
Vol 51 (7-9) ◽  
pp. 139-157
Author(s):  
Sohail Khan ◽  
Ishrat Noor ◽  
Tufail Habib ◽  
Muhammad Waseem
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Single Point ◽  
Reduction Rate ◽  
Excess Noise ◽  
Medium Density ◽  
Mathematical Algorithm ◽  
Average Value ◽  
Safe Level ◽  
Sound Levels

Consistent exposure to elevated sound levels results in noise health effects. The industrial environment represents a major source of such effects. There is significant variation in noise at different sections of such industries due to which most of the workers are exposed to these sounds at one or another level. In this study, a noise level measuring methodology is used for fixed and moving workers. This article introduces an algorithm for optimum selection of earmuff and earplug for different working places depending upon the exposure to noise. Medium density fiber industry is considered as a case for this study. It considers workers who are busy at a single point and face a consistent amount of noise as well as the workers who move and are exposed to a varying level of the noise. Noise level meters are used to measure the noise level at different points. At each point, the average value of the samples is taken. Based on the data collected, earmuff with high noise reduction rate is assigned to the workers closed to the machines. Implementation of the developed algorithm reduced the effect of noise on workers by 6.9%, 5%, and 16.3% for the chipper machine, pneumatic fan, and sanding machine, respectively, that were identified as the major source of noise at medium density fiber industry. This percentage reduction helped the workers to bring them to the optimum safe level of noise that is 85 dB and protect them from hearing loss severity due to frequency variations.

Noise Evaluation of Concrete Pavement

2013 ◽  
Vol 368-370 ◽  
pp. 1985-1989
Author(s):  
Ya Min Liu ◽  
Rao Rao Han ◽  
Zhi Jin Tao ◽  
Jie Chen
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Noise Spectrum ◽  
Concrete Pavement ◽  
Noise Characteristic ◽  
Groove Width ◽  
Concrete Pavements ◽  
Frequency Range ◽  
Porous Concrete ◽  
Noise Evaluation

In order to evaluate noise characteristic of concrete pavements with different texture, specimens were prepared carefully by varying groove parameters, such as groove width and space between grooves. Employing tire impact method, the noise level and noise spectrum of different pavements were analyzed. The results indicate that the noise level of transverse grooved concrete pavement is the greatest, and the followings are glossy concrete pavement and longitudinal grooved concrete pavement, porous concrete pavement has the lowest noise level. For grooved pavement, the noise level is promoted with increasing the space between grooves. Besides that, the noise level of transverse grooved concrete pavement becomes greater as the groove width increases. For longitudinal grooved pavement, there is a contrary tendency. It is porous concrete pavement for a frequency larger than 1600HZ. In the whole frequency range, the noise-reduction ability of transverse grooved concrete pavement is the worst.

scholarly journals A Study on Noise Reduction of Gear Pumps of Wheel Loaders Based on the ICA Model

2019 ◽  
Vol 16 (6) ◽  
pp. 999 ◽  
Author(s):  
Panling Huang ◽  
Liang Xu ◽  
Chuan Luo ◽  
Jianchuan Zhang ◽  
Feng Chi ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Noise Reduction ◽  
Noise Level ◽  
Gear Pump ◽  
Noise Sources ◽  
Environmentally Sustainable ◽  
Gear Pumps ◽  
Mixed Noise ◽  
Wheel Loaders

In order to reduce the noise level of wheel loaders caused by gear pumps and realize environmentally sustainable development, the noise generation mechanism of a gear pump was studied, and the influence of flow pulsation and gear impact on noise was analyzed. In order to reduce the interference of other noise sources on the noise level of the gear pump, a noise test rig was established. The mixed noise signals obtained from the rig test were separated using the ICA model. The ICA model includes the following algorithms: The fast Fourier transform (FFT), independent component analysis (ICA) and inverse fast Fourier transform (IFFT). Some theories about the influence of the teeth number and teeth profile on noise were analyzed by theory and simulation. A noise reduction strategy was proposed by increasing the teeth numbers and modifying the teeth profile of the gear pump. The tests results showed that the noise values of the external and the driver’s ear of the wheel loader were reduced to 1 and 2.2 dB (A), respectively. This proves the effectiveness of the optimization scheme of gear pump noise reduction.

Paper 16: A Study of Tractor Noise Control

1969 ◽  
Vol 184 (17) ◽  
pp. 149-169
Author(s):  
J. Matthews ◽  
J. D. C. Talamo
Keyword(s):  
Hearing Loss ◽  
Diesel Engine ◽  
Noise Reduction ◽  
Noise Level ◽  
Exhaust System ◽  
Low Noise ◽  
Acoustic Features ◽  
Noise Levels ◽  
Engine Design ◽  
High Incidence

A high incidence of hearing loss has been encountered among tractor drivers, and noise levels are shown to be further increased by the addition of cabs, particularly those which are structurally strong to resist crushing if the vehicle overturns. Some reductions in the noise level of the operator's environment can be obtained by covering the engine or by exhaust system modifications, while possible future improvements to diesel engine design may effect a significant improvement. However, it is proposed that noise reduction is likely to be achieved by attention to acoustic features of the operator's cab. The inclusion of resilient mounts, substantial floors and bulkheads, and acoustically absorbent linings are all shown to provide worthwhile improvements and, in combination, these measures can reduce noise levels from more than 100 dBA to 90 dBA or less. Where the tractor is fitted with a safety frame only, a low noise fabric cladding is shown to be feasible.

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