This study provides a general analysis for scattering of a planar monochromatic compressional sound wave by a fluid-filled viscoelastic spherical membrane immersed in an unbounded viscous heat-conducting compressible fluid. The thermoviscous effects in the fluid are incorporated by application of a thin boundary layer model. The dynamic viscoelastic properties of the spherical membrane are rigorously taken into account in the solution of the acoustic-scattering problem. Havriliak-Negami model for viscoelastic material behaviour along with the appropriate wave-harmonic field expansions and the pertinent boundary conditions are employed to develop a closed-form solution in form of infinite series. Subsequently, the basic acoustic quantities, such as the scattered far-field pressure directivity pattern, and the scattering cross section are evaluated for given sets of viscoelastic material properties. Numerical results clearly indicate that, in addition to the traditional fluid thermoviscosity-related mechanisms, dynamic viscoelastic properties of the obstacle can be of significance in sound scattering. The presented analysis is of practical interest in development of contrast agents for echocardiographic research with potential clinical applications.

In this paper, Valanis' steady creep theory with four creep parameters was derived from a liaison of the theory of deformation kinetics with internal isotropy and the theory of irreversible thermodynamics of continuous media with only one internal state variable.

According to the theory, steady creep rates under simple shear and simple tensile conditions are related and allow one to construct creep-parameters maps of high lead Pb/Sn solders (from 90% to 100% Pb). When testing temperatures are higher than solder's solvus temperature, microstructural transformation from lamellae α + β phase to solid solution α phase in the bulk specimens are considered in the construction of maps. Applications of maps in the 97.5Pb/2.5Sn solder joints creep tests need minor modifications due to dispersive precipitation of tin particles in lead matrix. As a result, the maps may provide estimated steady creep rates for the usage of finite elements analysis in the microsystem or electronic packaging analysis.

In this paper, an efficient macromodel extraction technique for dynamical MEMS gas damping effects is presented. The technique applies an Arnoldi-based model-order-reduction algorithm to generate low-order macromodels from a FEM approximation of the governing equation of the squeeze-film fluidic damping effect, the Reynolds equation. We demonstrate that this approach is more than 100 times efficient than previous approaches, which solve the Reynolds equation using transient finite-element/finite-difference methods. The generated gas-damping macromodels can be easily inserted into system-level modeling packages, such as SPICE, Saber and Simulink, for transient and frequency coupled-domain analysis. We also demonstrated that the simulated results are in good agreement with experimental results for various MEMS devices.

A simple model has been developed for the study of turbulent film condensation from downward flowing vapors onto a horizontal circular tube with variable wall temperature. The interfacial shear at the vapor condensate film is evaluated with the help of Colburn analogy. The condensate film flow and local/or mean heat transfer characteristics from a horizontal tube with non-uniform temperature variation under the effect of Froude number, sub-cooling parameter and system pressure parameter has been conducted. Although the non-uniform wall temperature variation has an appreciable influence on the local film flow and heat transfer; however, the dependence of mean heat transfer on the non-uniform wall temperature variation is almost negligible.

Broadband dispersion behaviors of wedge waves traveling along large-angled wedges are investigated with a laser ultrasound technique. Wedge waves are guided acoustic waves propagating along wedge tips. Until now, no elasticity-based close-form solution is available for the prediction of dispersion behavior of wedge waves. By assuming the wedge as a thin plate with variable thickness, McKenna obtained a theoretical approximation for the prediction of dispersion relation of truncated wedges within limited apex angle and bandwidth. The current research provides experimental data on wideband dispersion spectra of wedge waves traveling along large-angled wedges. It is found that the thin plate theory is accurate only within a small wavenumber regime. Also, a limiting behavior in the large wavenumber regime the ASF dispersion spectra are found to approach the Rayleigh wave speed.

The stationary values (maximum, minimum, saddle point) of Young modulus E(n) for a general anisotropic elastic materials is studied. The general results are then spcialized for monoclinic materials. Equations that provide the direction n for a stationary value are given. Some have an explicit solution. Other may require a numerical computation. The equations that required numerical solutions are two coupled polynomials of degree no more than four.

Explicit expressions of the direction n and the stationary values (maximum, minimum and saddle point) of Young's modulus E(n) for orthotropic, tetragonal, trigonal, hexagonal and cubic materials are presented. For the shear modulus G(n, m), explicit expressions of the extrema (maximum and minimum) and the two mutually orthogonal unit vectors n, m are given for cubic and hexagonal materials. We also present a general procedure for computing the extrema of G(n, m) for more general anisotropic elastic materials. It is shown that Young's modulus E(n) can be made as large as we wish for certain n without assuming that the elastic compliance s11, s22 or s33 is very small. As to the shear modulus G(n,m), it can be made as large as we wish for certain n and m without assuming that any one of the elastic compliance sαβ is very small. We also show that Young's modulus E(n) can be independent of n for orthotropic and hexagonal materials while the shear modulus G(n, m) can be independent of n and m for hexagonal materials.

A series of forced vibration tests were conducted on a proto-type pile foundation which is built in the Tainan Science-Based Industrial Park and is modeled on the foundation type of Taiwan High Speed Rail. The test method, analysis procedure and results of test are briefly introduced in this paper. Besides, a finite element method by using the computer program ABAQUS is used to simulate the test. Results obtained are in good agreement with the results of in-situ test, and both are helpful for understanding the characteristics of the ground responses of the site and for identification of the soil-structure interaction of Taiwan High Speed Rail foundation system.