Investigation on acoustic behavior of acoustic porous absorbers to ‎absorb sound energy and transmission loss index

Effect of porosity on the characteristics of underwater acoustic sound absorbers using theoretical models‎

Porous materials have good acoustic damping characteristics over a wide frequency range. As for sound waves, many small-scale pores in the coating materials can convert underwater-coating to rough surfaces. The main property of porous absorbents is their resistance against incident sound wave that leads to damping effect. From a physical point of view, damping occurs due to friction between flu...

the role of russia in transmission of energy from central asia and caucuses to european union

پس ازفروپاشی شوروی،رشد منابع نفت و گاز، آسیای میانه و قفقاز را در یک بازی ژئوپلتیکی انرژی قرار داده است. با در نظر گرفتن این منابع هیدروکربنی، این منطقه به یک میدانجنگ و رقابت تجاری برای بازی های ژئوپلتیکی قدرت های بزرگ جهانی تبدیل شده است. روسیه منطقه را به عنوان حیات خلوت خود تلقی نموده و علاقمند به حفظ حضورش می باشد تا همانند گذشته گاز طبیعی را به وسیله خط لوله مرکزی دریافت و به عنوان یک واس...

Prediction of Noise Transmission Loss and Acoustic Comfort Assessment of a Ventilated Window using Statistical Energy Analysis

In this paper, a novel analytical method was developed based on statistical energy analysis framework to evaluate sound transmission loss through ventilated windows. The proposed method was compared to numerical and analytical models available in the literature. Results showed the success and advantage of the proposed model in predicting the acoustic performance of the ventilated window and the...

Investigation of Acoustic Properties of Polymer Nanocomposites regarding Combined Sound Absorption and Insulation Characteristics

Introduction: Nowadays multiple techniques have been developed to noise control. One the most important way is the control based on sound absorption and insulation. The purpose of current study was to improve the acoustic properties of soft polyurethane foam regarding combined sound absorption and insulation characteristics. Materials and Methods: Polyacrylonitrile and polyvinylidine fluoride ...

Investigation of Acoustic Properties of Satin 7/1 Woven Fabrics Containing Hollow and Micro-porous Yarns

Acoustic Study of an Auditorium by the Determination of Reverberation Time and Speech Transmission Index

The quality of the communication between teachers and students and ultimately, of classroom education itself, is closely linked to the acoustic quality of the auditorium. This acoustic quality can be characterized based on the reverberation time (RT), speech transmission index (STI) and the sound insulation. In this context, an acoustic study was conducted in an auditorium located in the Higher...