نتایج جستجو برای: sound
تعداد نتایج: 104142 فیلتر نتایج به سال:
Open cell aluminum foams have good acoustic dampening properties. In this research, in order to improve the sound damping capacity of these foams, 0.9, 1.5 and 3wt% carbon nanotubes were added to the aluminum foam. Foams were produced by the space holder method in powder metallurgy. The results showed that Al-0.9wt%CNT nanocomposite foam had the highest average sound transmission loss in the fr...
Aquatic ecosystems are heterogeneous in terms of light and sound distribution. The aim of this study was to investigate the effect of environmental abiotic factors, light and sound stimuli, on Daphnia (Daphnia magna) swimming behaviour. Here, we examined behavioural changes of Daphnia (N=24) in response to light and sound treatments simultaneously. The treatments concerned a 2×2 design with br...
گرافیک مطبوعاتی در کنار تبلیغات بخشهای مهم و کاربردی گرافیک دیزاین را تشکیل می دهند . شاید به جرات بتوان ادعا کرد که اکثر طراحان گرافیک در این دو حوزه مشغول به کارند و معشیت خود را از این دو راه تامین می کنند. از این بین، مطبوعات به نسبت تبلیغات بیشتر مورد بی توجهی قرار گرفته و کیفیت نازل تولیدات آن در سطح جامعه، گویای این مدعاست، در حالی که سطح تاثیر این تولیدات در فرهنگ بصری جامعه و تشویق مخا...
abstract background: given the fact of irrecoverable consequences of noise in industrial societies and the environment, acoustic filter (silencer) is an instrument which obstacles the transmission of sound waves. a sort of this silencer is helmholtz resonator (branch amplifier) which comes to sound appropriate for low and below 200 hz frequencies in fan and channel noise. the purpose of this ar...
Background and Objective: Noise pollution is one of the serious environmental issue. Sound control technologies based on sound absorption and sound insulation are considered as the two widely used methods. Therefore, the aim of this study was to modify silica aerogel nanocomposites to improve its acoustic properties. Materials and Methods: This applied experimental research involved in examin...
Background and Objectives: Exposure to high levels of noise can lead to physical and psychological problems. The purpose of this study was to determine the sound level of welding centers in Babol. Materials and Methods: This descriptive study was randomly performed in 20 welding workshops in 2018. The sound level was measured by sound level meter. The researcher-made form was completed by the ...
Introduction: In recent years tend to use of natural fibers has increased in making sound absorbers. Fiber-based natural materials have low density, low production costs, and are biodegradable. Material and Methods: In this study, the effect of nanoclay and the behavior of the nanocomposite specimens containing tea waste, polypropylene, and nanoclay in the sound absorption coefficient are inve...
sound power is considered as an excellent measure for evaluating the efficiency of noise controls as well as for comparing noise sources in workrooms. this parameter can be determined by sound pressure or intensity based methods in real conditions of workrooms. this paper aims empirically to compare these in situ methods in relation to a typical industrial machine located in workroom in terms o...
Single unit recording has been used as a well-known technique to study the electrical behavior of neurons. In this respect, the classical methods are rather expensive. In this study a simple and inexpensive method for single unit recording studies has been introduced. Computer sound card was used for data acquisition. Neural responses were saved via simple sound applicable packages and then ana...
Background and Objectives: Many animal species are currently experiencing anthropogenic pollutions in their habitat. Noise pollution from human activities affects many species of animals. Noise pollution in terrestrial and aquatic ecosystems is prominently recognized as a source of stress and disruption of biological activities, and an important and pervasive global environmental pollutant. Rec...
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