نتایج جستجو برای: frequency noise

تعداد نتایج: 648515  

Journal: :رادار 0
آرش رضاپور پگاه رضاپور

in this research, active capacitance circuit and the feature of negative resistance are analysed in details. also, a new active filter is presented based on active capacitance circuit. for simulations, we used matlab and advanced design system(ads). proposed active filter (rf) is a narrow band filter. the results of simulation shows some aspects of sustainability and low noise feature. the circ...

ژورنال: تحقیقات موتور 2018
Asadi, M., Baloo, M., Jafari, M. J.,

Valvetrain is one of the major sources of noise and vibration in IC engines. The importance of cam surface quality parameters is highlighted in the valve train mechanisms with direct sliding contact between cam and tappet. In this paper, the influence of surface quality parameters on high frequency noise producing is investigated. The roughness and waviness of some intake and exhaust camshafts ...

Introduction: Hearing loss is one of the most common occupational diseases. In most workplaces, workers are exposed to noise and solvents simultaneously, so the potential risk of hearing loss due to solvents may be attributed to noise.  In this study we aimed to assess the effect of exposure to mixed aromatic solvents on hearing in the absence of exposure to hazardous noise.   Materials and Met...

ژورنال: طب کار 2016
عطارچی, میرسعید, محمدی, صابر, والی راد, فاطمه, پورزارع, غفور,

Introduction: Based on the results of some studies, concurrent exposure to organic solvents and noise in industrial areas can accelerate the amount of hearing loss. The aim of this study was to assess the effect of concurrent exposure to organic solvents and noise on high frequency hearing loss. Method: This was a cross-sectional analytic study conducted on 1029 tire manufacturing company wo...

Introduction: Steel industries are one of the major needs of the country. Noise pollution in steel production operations is an occupational hazard because of special equipment such as electric arc furnaces. The aim of this study was to evaluate noise pollution in various units of a steel company for determining the occupational exposure pattern. Methods: This was a cross-sectional and analyt...

جهانگیری, مهدی , حقیقی کفاش, زهره , فرهنگ دهقان, سمیه , منظم, محمد رضا , نصیری, پروین ,

Introduction: Noise is one of the most common health hazards at the workplaces that can cause not only somatic problems, but also adversely affect mental health. The aim of this study was to investigate and evaluate occupational noise exposure and noise annoyance in one of the petrochemical companies. .Material and Method: The study population included 47 people working in Administrative and ...

ژورنال: سلامت کار ایران 2018

Abstract: Background and aims: Using water pump in residential buildings to provide the required water pressure is accompanied by noise pollution and the annoyance of residents. So, the purpose of this study is to reduce water pump noise pollution with designed acoustic curtains in a residential building of Qazvin city.   Methods: The mean sound pressure level was measured before and ...

ژورنال: سلامت و محیط زیست 2009
ابراهیمی, حسین, رحیمی فروشانی, عباس, سلیمی, یحیی, منظم اسماعیل پور, محمدرضا, نصیری, پروین,

Backgrounds and Objectives: Noise in large cities is considered by the World Health Organization to be the third most hazardous type of pollution. Buses are an interesting object of study in the theme of noise pollution. They are at the same time a source of urban environmental (traffic) noise and occupational noise exposure source for drivers. The object of this study is Occupational noise exp...

Journal: :تحقیقات نظام سلامت 0
رستم گلمحمدی دانشیار گروه مهندسی بهداشت حرفه‎ای، دانشکده بهداشت و مرکز تحقیقات علوم بهداشتی، دانشگاه علوم پزشکی همدان، همدان، ایران محسن علی آبادی ستادیار گروه مهندسی بهداشت حرفه‎ای، دانشکده بهداشت، دانشگاه علوم پزشکی و خدمات بهداشتی درمانی همدان، همدان، ایران ابراهیم درویشی عضو مرکز تحقیقات بهداشت محیط و مربی گروه مهندسی بهداشت حرفه‎ای، دانشکده بهداشت، دانشگاه علوم پزشکی و خدمات بهداشتی درمانی کردستان، سنندج، ایران

background: in the steel industry, coke-fueled furnaces are used for smelting iron ore to produce cast iron are considered as sources of annoying noise.this study aims to evaluate the noise pollution blast furnace and sound source characteristics in order to present noise control measures in the steel industry. methods: measurement of noise level and its frequency analysis was performed using s...

جهانگیری, محمد , علی آبادی, محسن , گلمحمدی, رستم ,

Introduction: The Power plants are as the major industries that have a large number of workers, providing they health is important. Exposure to occupational noise is the pervasive physical agent in industries like power plants and may impact health and for safety status for people. Determination of the sources of noise in workplaces is important step in noise control plans. This study aimed to ...

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