翻訳と辞書 Words near each other ・ Acoustic Live (Erasure album) ・ Acoustic Live (Five for Fighting EP) ・ Acoustic Live at the WOW ・ Acoustic Live from the Gibson Lounge ・ Acoustic Live in Newcastle ・ Acoustic Live! (Adam Lambert EP) ・ Acoustic lobing ・ Acoustic location ・ Acoustic Lounge on KSFS ・ Acoustic LP ・ Acoustic lubrication ・ Acoustic Masters I ・ Acoustic meatus ・ Acoustic membrane ・ Acoustic metamaterials ・ Acoustic metric ・ Acoustic microscopy ・ Acoustic mine ・ Acoustic mirror ・ Acoustic model ・ Acoustic music ・ Acoustic network ・ Acoustic Nights Montreal ・ Acoustic ohm ・ Acoustic paramagnetic resonance ・ Acoustic phase conjugation ・ Acoustic phonetics ・ Acoustic plaster ・ Acoustic quieting ・ Acoustic radiation Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Acoustic metric ： ウィキペディア英語版 Acoustic metric In mathematical physics, a metric describes the arrangement of relative distances within a surface or volume, usually measured by signals passing through the region – essentially describing the intrinsic geometry of the region. An acoustic metric will describe the signal-carrying properties characteristic of a given particulate medium in acoustics, or in fluid dynamics. Other descriptive names such as sonic metric are also sometimes used, interchangeably. == A simple fluid example == For simplicity, we will assume that the underlying background geometry is Euclidean, and that this space is filled with an isotropic inviscid fluid at zero temperature (e.g. a superfluid). This fluid is described by a density field ρ and a velocity field $\backslash vec$. The speed of sound at any given point depends upon the compressibility which in turn depends upon the density at that point. This can be specified by the "speed of sound field" c. Now, the combination of both isotropy and Galilean covariance tells us that the permissible velocities of the sound waves at a given point x, $\backslash vec$ has to satisfy :$(\backslash vec-\backslash vec(x))^2=c(x)^2$ This restriction can also arise if we imagine that sound is like "light" moving though a spacetime described by an effective metric tensor called the acoustic metric. The acoustic metric $\backslash mathbf=g\_dt\; \backslash otimes\; dt+2g\_dx^i\; \backslash otimes\; dt+g\_\; dx^i\; \backslash otimes\; dx^j$ "Light" moving with a velocity of $\backslash vec$ (NOT the 4-velocity) has to satisfy :$g\_+2g\_u^i+g\_u^i\; u^j=0$ If : where α is some conformal factor which is yet to be determined (see Weyl rescaling), we get the desired velocity restriction. α may be some function of the density, for example. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Acoustic metric」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.