巻号一覧
34 巻, 12 号
選択された号の論文の8件中1～8を表示しています
- |<
- <
- 1
- >
- >|
-
久野 和宏, 池谷 和夫原稿種別: 本文
1978 年 34 巻 12 号 p. 687-692
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーStatistical properties of total noise exposure and its time average due to road traffic are studied theoretically. At first the noise emitted in an open half space by freely flowing vehicles on a straight lane is disccused. The cumulants and the time correlation of sound intensity have been obtained using the regression equations by which PWLs of vehicles are related to their velocities. Simple formulae for calculating L_<eq> have also been derived. They show that the dispersions of velocity and PWL of vehicles increase L_<eq> generally. The variation coefficients of the total noise exposure and its time average decrease monotonically with increasing the observation time length and the distance from a road. Then a more general case of road traffic noise is studied using a simplified model. A measure of stability of the total noise exposure and its time average as statistical parameters is proposed. The conditions to confirm the stability of these parameters have been derived.抄録全体を表示PDF形式でダウンロード (767K) -
菊池 年晃原稿種別: 本文
1978 年 34 巻 12 号 p. 693-699
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーThe liquid filled spherical lenses have been investigated by several authors. Though the lenses of this type have some advantages, they are structually delicate. In this paper, the homogenous spherical lenses are constructed by molding the mixture of RTV silicon rubber and zinc powder. The focusing properties of them are measured and compared with the calculated results for the lens diameter to wavelength ratios smaller than 25. It is shown that the pressure gain, the position of the focal point, and the beamwidth are determined by the index of refraction and k_a (k:the wavenumber in water;a:the radius of lens). The position of the focal point moves outward, oscillating back and forth along the lens axis as the k_a increases. Although the pressure level at the surface of lens increases with the index of refraction, the pressure fluctuation also increases so that the lens with the index of refraction near 1. 55 is useful at small values of k_a(k_a<20). It is shown that the mixture of RTV silicon rubber and zinc powder is a useful lens material.抄録全体を表示PDF形式でダウンロード (803K) -
奥田 襄介原稿種別: 本文
1978 年 34 巻 12 号 p. 700-703
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーUnder the condition of sound power continuity, a theoretical investigation is made of the problem of the reflection of sound wave at the end of a pipe with fluid flow. When the Mach number of the flow towards the end of the pipe is M and the load impedance is (R+jX)Z_0 where Z_0 is the characteristic impedance of the pipe without flow, the reflection coefficient of sound pressure at the end is given by -[(1-M)/(1+M)][(1-R-jX)/(1+R+jX)]. The equivalent wave length in the pipe is shortened by (1-M^2), and the ratio of the sound pressure and the volume velocity at any cross section of the pipe is given by a virtual impedance which is the sum of the real impedance and MZ_0. For example, the virtual impedance at the end is (M+R+jX)Z_0. The sound power is given by |U_0|^2[R+(1+R^2+X^2)M/2]Z_0 where U_0 is the volume velocity at the end.抄録全体を表示PDF形式でダウンロード (405K) -
大家 左門, 竹内 龍一原稿種別: 本文
1978 年 34 巻 12 号 p. 704-710
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーThe sound fields radiated from a surface of porous material vibrating uniformly were theoretically investigated. We adopted a capillary tube model as an analytical model of porous material to compute the interactive effects between the fluid in the pore and the solid frame of the porous material in motion. We made some discussions and numerial calculations on the radiation efficiency coefficients as one dimensional problems. For the porous material of finite thickness placed on a rigid piston, the radiation efficiency coefficients were measured and compared with the predicted ones obtained based on the assumption that the porous material vibrates uniformly. Roughly saying from these result, the radiation efficiency coefficient generally becomes small when the porous material placed on the piston vibrates in high frequency range.抄録全体を表示PDF形式でダウンロード (826K) -
山渕 龍夫, 加川 幸雄原稿種別: 本文
1978 年 34 巻 12 号 p. 711-720
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーThe finite element technique is applied to a problem of composite piezoelectric transducers for ultrasonic radiation and their characteristics, i. e. , input admittances at the electrical terminals, acoustic radiation loading effects, near field sound pressure distributions and directional patterns, are analyzed. In each of our previous works(of piezoelectric resonators and acoustic transmission-radiation systems), the technique proved useful to predict the behaviours. Two separate programs have thus been developed. These programs are now combined, with compatibility for sound pressure and particle velocity introduced for the resonator-medium interface. It is again confirmed that the technique is useful for the computer simulation and computer-aided design of this kind of problems.抄録全体を表示PDF形式でダウンロード (893K) -
木本 日出夫, 伊東 照起, 広瀬 達三原稿種別: 本文
1978 年 34 巻 12 号 p. 721-723
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーPDF形式でダウンロード (248K) -
藤原 恭司原稿種別: 本文
1978 年 34 巻 12 号 p. 724-731
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーPDF形式でダウンロード (1039K) -
安本 義正原稿種別: 本文
1978 年 34 巻 12 号 p. 732-737
発行日: 1978/12/01
公開日: 2017/06/02
ジャーナル フリーPDF形式でダウンロード (857K)
- |<
- <
- 1
- >
- >|