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.
Three-dimensional elasticity model for a decoupling coating on a rectangular plate immersed in a heavy fluid.
This paper presents an analysis of the vibroacoustic response of a finite, simply supported rectangular plate covered by a layer of decoupling material and immersed in a heavy fluid. An exact formulation using the three-dimensional theory of elasticity for the decoupling material is derived for this problem, thereby extending previous studies that were limited to infinite plates. The paper details the constitutive equations of the problem and the analytical method of solution. Numerical results show that shear waves in the decoupling material generally have little influence on the sound radiation in the heavy fluid. Comparisons with a locally reacting model of the decoupling material and with the simple model of House [Proc. I.O.A. 13(3), 166-173 (1991)] are also presented.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.