Underwater sound radiation by a layered infinite elastic plate with discontinuity
The underwater sound radiation from layered structu re is determined by the properties of elastic waves in the structure and by interaction between structural/structur al waves and between structural/fluidal waves. In t his paper, a model of a layered infinite plate is used to addres s how the properties and interaction influence the near field and far field characteristics of the radiated sound. In par ticular, the effect of structural discontinuity int roduced to the layered plate by a finite signal conditioning plate on unde rwater sound radiation is investigated. The scatter ing of structural waves in the layered plate by the signal conditioni ng plate is used to explain the changes in the radi ated sound due to the discontinuity.
Acoustic radiation from an elastic baffled rectangular plate covered by a decoupling coating and immersed in a heavy acoustic fluid
The vibroacoustic behavior of an elastic, simply supported rectangular plate covered by a locally reacting decoupling layer supporting thickness deformation is presented. The model simulates the vibration and acoustic response of the system immersed in water and subjected to a point force disturbance. A simplified version of the theory is derived in the limiting case of a large decoupling (low mechanical impedance of the layer/high frequency). An appropriate vibratory indicator, representative of the acoustic attenuation provided by the decoupling treatment, and independent of the structure dimensions, is also investigated from the perspective of small-scale laboratory characterization.
A new power measuring circuit using a bridge-connected magnetic circuit and another magnetic core
The authors describe the operating characteristics of an oscillating circuit using a bridge-connected magnetic circuit and another magnetic core. A square-shape output voltage is obtained in the oscillating circuit. The pulsewidth in positive and negative half cycles of output voltage changes with the current of the U-form core windings and with the signal voltage applied to the exciting windings. The mean value of the output voltage varies in proportion to the product of the current and the signal voltage. Utilizing this feature, an application of the oscillating circuit to a novel power measuring circuit of simple construction is presented. >