نتایج جستجو برای: acoustic impedance
تعداد نتایج: 120231 فیلتر نتایج به سال:
Introduction: Sound absorption coefficient determination is one of the most important factors among material selection for indoor noise control. The objectives of this study were: 1) comparison sound absorption coefficient of different materials by standing wave ratio and transfer function methods, and 2) developing a regression model in adjusting provided results. Methods: In this study, 46 a...
Non-Destructive Testing & Evaluation methods are developed to inspect and investigate materials and structures. Ultrasonic Testing is an NDT method can be used for measuring the thickness of objects, as one of its significant applications. The objective of this paper is designing and applying an intelligent UT fuzzy control system for evaluating the thickness of thin metal objects in a range of...
The effect of perforation impedance on the acoustic behavior of reactive and dissipative silencers is investigated using experimental and computational approaches. The boundary element method (BEM) is applied for the prediction of transmission loss of silencers with different perforation geometries. The variations are considered in the porosity (8.4 and 25.7%) and hole diameter (0.249 and 0.498...
Recent military conflicts have provided evidence of a new mode of lower extremity injury as a result of under-vehicle blasts. Extreme vehicle design elements have decreased the frequency of hull breech into the occupant compartment, yet catastrophic injuries to the lower extremities continue to occur. Previous studies of shock wave-induced injuries, such as blast lung, have highlighted acoustic...
Introduction: In Iran country, there is a lack of reliable data on acoustic characteristics of building materials applied in the offices and industrial rooms. This study aimed to investigate noise absorption characteristics for current building and acoustics materials and provided the acoustic database. Method: In this cross sectional study, the minimum of 60 building and acoustic mate...
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