摘要:

Formulas previously derived for multipath CW propagation in time‐dependent channels are shown to be special cases of corresponding formulas for repreated‐pulse propagation. General expressions that relate the CW and repeated‐pulse average power outputs in time‐dependent channels are derived.

ISSN:0001-4966    

DOI:10.1121/1.1913117

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The imaginary part of the effective density of a fluid or of a viscoelastic material is zero. The contrary notion arises from an inadequate definition of characteristic impedance. The attenuation cannot exceed 2π Np per wavelength.

ISSN:0001-4966    

DOI:10.1121/1.1913120

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Spectral analyses of underwater backscattered sound are carried out. Measurements are presented showing different Doppler shifts for volume and surface reverberation. Reversal of Doppler polarity is shown for 180° rotation of the underwater sound transducer. The measurements are compared with predictions of a first‐order diffraction model for surface reverberation.

ISSN:0001-4966    

DOI:10.1121/1.1913121

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The response of a nonlinear oscillator to narrow‐band random excitation is investigated experimentally using a straight beam with clamped ends excited by motion of its supporting base. Multivalued or “jump”‐type response behavior is observed for a range of excitation levels centered near the first‐mode resonant frequency. The time spent in response levels and the magnitudes of the levels are studied and compared with harmonic response. Large peaks in displacement response are seen for excitation centered at the third‐order superharmonic frequency.

ISSN:0001-4966    

DOI:10.1121/1.1913122

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP