Mesoscale Modeling and Validation of Texture Evolution during Asymmetric Rolling and Static Recrystallization of Magnesium Alloy AZ31B

The focus of the present research is to develop an integrated deformation and recrystallization model for magnesium alloys at the microstructural length scale. It is known that in magnesium alloys nucleation of recrystallized grains occurs at various microstructural inhomogeneities such as twins and localized deformation bands. However, models need to be developed that can predict the evolution of the grain structure and texture developed during recrystallization and grain growth, especially when the deformation process follows a complicated deformation path such as in asymmetric rolling. The deformation model is based on a crystal plasticity approach implemented at the length scale of the microstructure that includes deformation mechanisms based on dislocation slip and twinning. The recrystallization simulation is based on a Monte Carlo technique that operates on the output of the deformation simulations. The nucleation criterion during recrystallization is based on the local stored energy, and the Monte Carlo technique is used to simulate the growth of the nuclei resulting from local stored energy differences and curvature. The model predictions are compared with experimental data obtained through electron backscatter analysis and neutron diffraction.     

A graphical surface navigation technique for multiobjective programming

A methodology is presented to explore the tradeoffs associated with the numerous solutions typically obtained through multiobjective optimization procedures. The method is a graphical surface navigation technique based on a spring equilibrium analogy. The procedure is cast in the framework of an interactive graphical session, which permits a user easily to move from one noninferior point to another on the objective response surface. A zooming capability is also incorporated which facilitates refinement of the noninferior set approximation over particular areas of interest and as well, provides for the capability to examine the exact noninferior set. A three-dimensional and a five-dimensional problem are used to illustrate the method.     

Triangulation method for determining capillary blood flow and physical characteristics of the skin

A method capable of measuring blood flow at precise depths within the skin is described. The method determines the static and the dynamic properties of light that is backscattered to small areas on the surface of the skin at several contiguous locations along the expected trajectory of laser-light propagation. From observations the method has been shown to be capable of determining physical characteristics that are unique to the different layers of the skin.     

Power balance considerations for brushless doubly-fed machines

This paper discusses the power balances in a brushless doubly-fed machine (BDFM). Equations of power in the two stator windings and the rotor circuit, showing the distribution of electrical and mechanical powers in the air-gap, are obtained in two different speed ranges of BDFM synchronous mode operation. Comparisons vis-a-vis power distribution are made between the wound-rotor induction machine (WRIM) and the BDFM. A brief analysis of the power balances, along with experimental data points obtained using a laboratory prototype machine, are given