A combined noise source model based on vertical coherence to quantify the proportions of two types of noise power.

With the vigorous development of maritime trade, the frequency band from 100 to 1500 Hz of shallow-sea ambient noise is not only affected by surface wind-induced noise but also the contribution of ship noise. Shallow-sea ambient noise can be described by a linear combination of surface wind-induced noise sources and ship noise sources. By using the correspondence between the real part of the vertical coherence and vertical energy flux, this work establishes a combined noise source model based on vertical coherence.

Similitude method for self-noise under boundary layer pressure fluctuation excitation.

In this paper, the authors propose a similitude method based on the Π-theorem to predict the noise generated by pressure fluctuations along the boundary layer of a full-scale model by using a small-scale model. We begin by investigating the theory of the similitude method and introducing an approach to control the flow regime. We also provide an account of active and passive methods of controlling the flow regime.

Measurement of Underwater Acoustic Energy Radiated by Single Raindrops.

Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise.

A Flow Velocity Measurement Method Based on a PVDF Piezoelectric Sensor.

To measure the flow velocity of a fluid without affecting its motion state, a method was proposed based on a polyvinylidene fluoride (PVDF) piezoelectric film sensor. A self-made PVDF piezoelectric sensor placed parallel with the flow direction was used to measure the flow velocity. First, the piezoelectric characteristics of PVDF were obtained theoretically.