نتایج جستجو برای: sound
تعداد نتایج: 104142 فیلتر نتایج به سال:
Abstract Background Sound is one of the most important work-related risk factors and most widespread physical factors threatening the health of workers. Almost one of the best ways to control the sound, is sound absorber. Due to the extensive entrance nano in various fields of science one their applications design and use sound-absorbing panels containing nanoparticles.The aim of this stu...
Background and Objective: Noise pollution causes many physiological, psychological, economic and social effects on human life. This issue is more important in the environment of industrial workplaces. This research aimed to adopt the functions of GIS for evaluating and spatial analysis of noises in industrial environments. Materials and Methods: At the initial step, the spatial data for indust...
introduction: the improvement of technology has increased noise levels in hospital wards to higher than international standard levels (35-45 db). higher noise levels than the maximum level result in patient’s instability and dissatisfaction. moreover, it will have serious negative effects on the staff’s health and the quality of their services. the purpose of this survey is to analyze the level...
in the present work, the influence of aging temperature on mechanical properties and sound velocity of maraging steel m350 was investigated. for this purpose, first, samples were solution annealed at 825◦c for 2 hours and then age hardened at 510◦c-600◦c for 3 hours. hardness, tensile and impact tests were used for determining mechanical properties and longitudinal ultrasonic velocity was used ...
conclusions according to the results of this study, with increasing load of traffic, there is an increasing need for proper consideration plans to control noise pollution and prevent its effects. results according to the research findings, the equivalent sound pressure levels in all stations were 76.28 ± 3.12 db (mean ± sd). according to sound measurements and the survey questionnaire, noise po...
Muffler is a part of the vehicle exhaust system that absorb or reflect sound waves to reduce exhaust noise. One of the most important determinants of a muffler performance is the amount of attenuation that has on its input wave; this parameter is known as sound transmission loss. Four - mic standard test is one way to determine this parameter which is used in this paper. In this study, a test d...
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