نتایج جستجو برای: Noise reduction

تعداد نتایج: 666195  

Journal: :journal of electrical and computer engineering innovations 2014
sattar samadigorji bijan zakeri mohammadreza zahabi

the aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. for this purpose, first, an exact mathematical model of phase locked loop (pll) based frequency synthesizer is described and analyzed. then, an exact closed-form formula in terms of synthesizer bandwidth and total output phase noise is extracted. based on this formula, the phase ...

Journal: :journal of advances in computer research 0

the speech enhancement techniques are often employed to improve the quality and intelligibility of the noisy speech signals. this paper discusses a novel technique for speech enhancement which is based on singular value decomposition. this implementation utilizes a genetic algorithm based optimization method for reducing the effects of environmental noises from the singular vectors as well as t...

Journal: :jundishapur journal of health sciences 0
gholam abbas shirali department of occupational health engineering, school of health, ahvaz jundishapur university of medical sciences, ahvaz, ir iran gholam abbas shirali department of occupational health engineering, school of health, ahvaz jundishapur university of medical sciences, ahvaz, ir iran mohammad javad zareh sakhvidi department of occupational health engineering, school of health, shahid sadoughi yazd ,university of medical sciences, hamedan, ir iran mohammad javad zareh sakhvidi department of occupational health engineering, school of health, shahid sadoughi yazd ,university of medical sciences, hamedan, ir iran

this paper tries to determine efficiency of noise control method using fuzzy logic and based on collected data. from among various methods of noise control in workplace, sex methods (enclosure, installing noise absorber, enclosure and absorber, active, and administrative control, and personal protective equipment) were typically selected based on experts' judgment. for each of selected control ...

Journal: :Sen'i Kikai Gakkaishi (Journal of the Textile Machinery Society of Japan) 1972

Journal: :iranian journal of medical physics 0
sh. olumi m.sc. in medical physics, tarbiat modarres university, tehran, iran h. rajabi assistant professor, medical physics dept., tarbiat modarres university, tehran, iran s.r. zakavi associate professor, nuclear medicine dept., imam reza hospital, mashhad university of medical sciences, mashhad, iran e. hajizade associate professor, biostatistics dept., tarbiat modarres university, tehran, iran h. ghiasi m.sc. in medical physics, torfe hospital, tarbiat modarres university, tehran, iran

introduction: one of the major problems in the development of nuclear medicine images is the presence of noise. the noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a fourier transform environment. the main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

ژورنال: سلامت کار ایران 2017

Background and aims Nominal noise reduction rating of the earmuff manufacturers can be different compared with the actual noise attenuation rating. The current study aimed to determine the actual noise reduction rate of current hearing protection devices in the real workplaces using a field microphone in real ear method (FMIRE). Methods: In this cross-sectional study, five common earmuffs we...

Journal: :Nature Chemical Biology 2020

Introduction:One of the recommended methods for evaluation effectiveness of hearing protection is use the acoustic fixture accordance with standard ISO 4869-3. The aim of this study was evaluate the acoustic performance of fixture for using in noise reduction rate  tests of hearing protection devices in the laboratory. Methods: In this cross-sectional study , noise reduction rates o...

Journal: :رادار 0
احمد شفیعی احسان یزدیان مجتبی بهشتی

speckle is a granular disturbance in coherent images such as synthetic aperture radar (sar) images, modeled as a multiplicative noise. this noise degrades the sar image and complicates the image exploitation using automated image analysis techniques. several approaches have been developed to reduce the effect of speckle noise. recently, the application of compressed sensing (cs) is explored in ...

ژورنال: ارگونومی 2016
بیابانی, اعظم, علی آبادی, محسن, گلمحمدی, رستم,

Introduction: Nominal noise reduction rate of the earmuff manufacturers can be different compared with the actual attenuation rate. The present study aimed to determine the actual noise reduction rate of common hearing protection devices using microphone in real ear method. Materials and Methods: In this study, five brands of common earmuffs used in Iranian industries were investigated on 30...

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