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Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness an tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.. [ABSTRACT FROM AUTHOR]

This paper presents an energy function approach to assess power system transient stability impacts following increased penetration of asynchronous generation plants. Here, the asynchronous windfarm generation is considered as an equivalent conventional synchronous generator with negligible inertia. Assessment had been carried out on three-machine nine-bus test system to compute critical energy and critical fault-clearing time using potential energy boundary surface method. A new representation of plotting contours of critical clearing times on inertia space is presented. This enables estimation of additional inertia required for a network in the event of inertia reduction of other machines. Results of the simulation and new graphical method confirm that transient stability margin of the system reduces with increased penetration of asynchronous generation. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]