Acoustic non-destructive testing of high temperature degraded concrete with comparison of acoustic impedance [PDF]
MATEC Web of Conferences, 2018 The paper is focused on non-destructive measurement of high temperature degraded concrete test specimens of three mixtures different by the use of coarse aggregate. Testing is done by ultrasonicpulse velocitymethod and Impact-Echo method. Non-destructive
Dvořák Richard +2 more
doaj +6 more sources
Acoustic transmission loss in Hilbert fractal metamaterials [PDF]
Scientific Reports, 2023 Acoustic metamaterials are increasingly being considered as a viable technology for sound insulation. Fractal patterns constitute a potentially groundbreaking architecture for acoustic metamaterials.
Gianni Comandini +3 more
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2011 The accurate evaluation of the ground reflection effect is of importance for acoustic measurement conducted during static-firing tests of rocket motors. The effectiveness of existing acoustic impedance models was examined by comparing experimental data collected from acoustically hard surfaces. Through these comparisons and the subsequent evaluation of
Kyoichi Ui +5 more
semanticscholar +5 more sources
Experimentally testing impedance boundary conditions for acoustic liners with flow: Beyond upstream and downstream [PDF]
Journal of Sound and Vibration, 2020 Impedance eduction experiments on acoustic liners with flow have systematically shown the educed impedance depending on the direction of the incident wave. Recent attempts to model this dependence include impedance boundary conditions with an additional degree of freedom. In this case, both upstream and downstream acoustic sources must be used to educe
André Mateus Netto Spillere +3 more
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Identification of uncertainty levels of acoustic properties of biocomposites under different mounting conditions in impedance tube tests [PDF]
Noise Control Engineering Journal, 2021 Impedance tube method is widely used to measure acoustic properties of materials. Although this method yields reliable acoustic properties for soft textured materials, uncertainty levels of measured acoustic properties for hard materials, including biocomposites, can be quite large, mainly due to uncertain mounting conditions.
Körük, Hasan +3 more
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Test of single degree of freedom acoustic treatment impedance models for multimodal acoustic propagation in duct with flow [PDF]
The Journal of the Acoustical Society of America, 2017 Passive acoustic treatments, also called liners, are the main solution to noise problems. The Single Degree Of Freedom (SDOF) acoustic treatment, composed of a thin material (perforated plate) affixed to air cavities with a rigid bottom, constitutes a solution.
Solène Moreau +2 more
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Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 2: Material Characterization and Rain Erosion Testing Evaluation [PDF]
Coatings, 2020 Under droplet impingement, surface leading edge protection (LEP) coating materials for wind turbine blades develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. The stress-strain coating LEP behavior at a working frequency range depends on the specific LEP and on the material and operational conditions ...
Luis Domenech +5 more
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An Acoustic Impedance Model for Evaluating Ground Effect of Static-Firing Tests on Rocket Motors
JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2010 Evaluation of ground effect is important for acoustic measurement in static-firing tests on rocket motors. The effectiveness of existing acoustic impedance models is examined by comparing with some experimental results. Through the comparison and evaluation of effect of meteorological condition, it is confirmed that the existing impedance models are ...
Kozo Fujii +5 more
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Mechanical and Acoustic properties of Bagasse – Coconut Coir based Hybrid Reinforced Composites
Journal of Natural Fibers, 2022 In this paper, a hybrid composite is developed from natural fibers of bagasse and coconut coir. The mechanical and acoustic properties of the hybrid composites are investigated.
M.K. Marichelvam +2 more
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impedance tuning a method for active control of the acoustic boundary conditions of combustion test rigs [PDF]
, 2009 Eine der größten Herausforderungen für die Entwicklung zukünftiger schadstoffarmer Gasturbinenkraftwerke ist die Gewährleistung eines stabilen Verbrennungsprozesses. Um die immer strikter werdenden Emissionsrichtlinien, vor allem hinsichtlich NOx, zu erfüllen, führte die Gasturbinenindustrie die Mager-Vormisch-Verbrennung ein.
Mirko R. Bothien
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