نتایج جستجو برای: other acoustic parameters such as sound velocity
تعداد نتایج: 6919982 فیلتر نتایج به سال:
colonialism is an important factor in cultural production and many of cultural constructs all over the world. english and english language teaching are at the center of the contemporary world. postcolonial literature, the genre achebe exercised, is a kind of historical text which has become central to different debates and criticisms. in this thesis, different elements related to the colonial...
abstract part one: the electrode oxidation potentials of a series of eighteen n-hydroxy compounds in aqueous solution were calculated based on a proper thermodynamic cycle. the dft method at the level of b3lyp-6-31g(d,p) was used to calculate the gas-phase free energy differences ,and the polarizable continuum model (pcm) was applied to describe the solvent and its interaction with n-hydroxy ...
in this research we have studied the effect of some transition-metals (cu, ag and au) substitutions on two-electron reduction potential of flavins by application of dft method. all geometries have been optimized at blyp level of theory and “6-31+g** + lanl2dz” mixed basis set. the frequency job at the same method and basis sets has been performed to obtain gibbs free energy of compounds. it h...
Introduction: Reducing noise pollution has become an essential issue due to the increase in public concern and also social demands for a better lifestyle. Using sound absorption materials is a preferred method to reduce the noise pollution. Undesirable properties of pure polyurethane such as poor absorption of mechanical energy in narrow frequency ranges can be improved by providing polymeric n...
1 Abstract-A new parameter was recently developed by Jeffery M. Fisher (M.S.) for use in Active Structural Acoustic Control (ASAC) which showed potential for achieving better sound radiation reduction than current parameters. This parameter, known as “Vcomp,” uses spatial derivatives to approximate radiation mode shapes and was shown analytically to produce results comparable to control of radi...
1. To demonstrate theoretically emergence of the deterministic Green’s functions (GFs) from noise sources distributed in a volume and on boundaries in inhomogeneous, fluid-solid environments with dissipation. 2. To investigate a relation between the deterministic GFs and a two-point correlation function of noise in a low-frequency regime where stationary-point arguments become inapplicable. 3. ...
Background and aims: In recent years, in most countries of the world, the provision of a calming environment without disturbing noise has become a need, which has subsequently led to significant growth in noise control techniques. It is now well documented that prolonged over-exposure to the excessive levels of environmental noise not only induces disabling hearing impairment but also contribut...
We demonstrate theoretically that the periodic multilayer Epoxy/Glass supports acoustic frequency bands sensitive to the changes of temperature. Due to the strong variation of the sound velocity in the Epoxy, the width of the band gaps and the midgap frequencies descend when the temperature passes from 0 to 100°C. The transmittance spectrum shows that this system can be useful as a sound filter...
To realize the sound pressure unit directly, the method of sound pressure measurement based on acoustic particle velocity with LDA technique was described. In order to get a simple acoustic field, a travelling wave tube was designed. The sound pressure distribution obtained by microphone along the tube was measured. The result showed the acoustic field inside the tube could be considered as tra...
it is definitely necessary to understand the concept and behavior of causation of life insurance policies and its determinants for insurance managers, regulators, and customers. for insurance managers, the profitability and liquidity of insurers can be increasingly influenced by the number of causation through costs, adverse selection, and cash surrender values. therefore, causation is a materi...
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