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Full-Text Articles in Physics

Propagation Of Elastic Waves Through Inhomogeneous, Anisotropic Materials , Ali Minachi Jan 1992

Propagation Of Elastic Waves Through Inhomogeneous, Anisotropic Materials , Ali Minachi

Retrospective Theses and Dissertations

The recent advances in the field of ultrasonic nondestructive inspection have demanded a more precise knowledge of the propagation of sound beams within materials. Quantitative models for propagation of ultrasonic fields from a transducer can be used as tools to both analyze the inspection data and to predict inspection results. An approximate Gauss-Hermite model was developed a few years ago to predict the ultrasonic fields radiated into isotropic and anisotropic materials, through planar or simply curved interfaces by focused or unfocused transducers. The paraxial approximation used in the development of that model has allowed many functions to be evaluated analytically ...


Determination Of Secondary Sources In Noise Cancellation With Boundary Element Method , Guang-Hann Chen Jan 1992

Determination Of Secondary Sources In Noise Cancellation With Boundary Element Method , Guang-Hann Chen

Retrospective Theses and Dissertations

The direct boundary element method is proposed in this thesis to solve acoustic radiation problems as well as to achieve regional noise cancellation in half space with uniform finite impedance over the surface. The boundary integral equation and half space Green's function were derived to accomplish these goals. Those formulations were verified by comparing numerical simulations with theoretical solutions as well as experimental results. In addition, the above formulations were extended to achieve regional noise cancellation in half space by applying the boundary element method;Two methods were investigated to obtain noise cancellation in desired regions. They are the ...


Solution Of Viscous Flow Problems By Using The Boundary Element Method , Abdel-Magid Abdel-Latif Abdalla Jan 1992

Solution Of Viscous Flow Problems By Using The Boundary Element Method , Abdel-Magid Abdel-Latif Abdalla

Retrospective Theses and Dissertations

A scheme based on the Boundary Element Method (BEM) for solving the problem of steady flow of an incompressible viscous fluid is presented in this thesis. The problem is governed by both Navier-Stokes (N-S) equations and the continuity equation. The fundamental solution of the two-dimensional N-S is derived, and the partial differential equations are converted to an integral equation;The computer code is flexible enough to handle a variety of boundary and domain elements with different degrees of interpolation polynomial. Boundary and domain integrals over corresponding elements are evaluated analytically. The Newton Raphson iteration scheme accompanied by a relaxation factor ...


Theory Of Eddy Current Inspection Of Layered Metals , Erol Uzal Jan 1992

Theory Of Eddy Current Inspection Of Layered Metals , Erol Uzal

Retrospective Theses and Dissertations

Some forward and inverse problems related to layer sizing in eddy current nondestructive evaluation (NDE) were examined and experimental tests were done. An air-core or ferrite-core eddy current probe coil above a half space is considered. The half space's conductivity changes only as a function of depth, but otherwise it is arbitrary. A numerical method for the computation of coil impedance based on the exact solution of Cheng, Dodd and Deeds (International Jour. of Nondestructive Testing, 3, 109-130,1971) is described. Also, for a specific conductivity profile involving the hyperbolic tangent function, the exact solution for the impedance is ...