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Lagrangian coherent structures (LCSs) in the time-varying flow of the upper atmosphere are found. The Horizontal Wind Model 2014 (HWM14) is used to simulate the neutral winds of the thermosphere at 150, 250, and 350 km altitude, for quiet and active geomagnetic conditions. Then LCS analysis of HWM14 winds at 100 km altitude is used to investigate space shuttle water vapor plume transport. LCSs are found to exist in the lower thermosphere, but are more prominent at 250 km and 350 km, at 40° - 80° latitudes on the dayside. Ionosphere-thermosphere coupling manifests in the response of thermospheric LCSs to geomagnetic activity. The LCSs shift equatorward and eastward, developing a more complex topology in the apparent form of two cells in the northern hemisphere high latitude zone. We also show for the first time that the LCS demarcates the high-latitude boundary of shuttle plume observations after 48 hours of transport.

Using the current processing methods for aluminum conductors, any addition to mechanical strength negatively impacts their electrical conductivity (EC). This trade-off can be seen in common aluminum conductors such as AA1350-H19 which has a relatively high EC (~61%IACS), but low tensile strength (~180 MPa), as opposed to AA6201-T81 having a lower EC (~52.5%IACS) and higher tensile strength (~330 MPa). Presented in this work is the development of new low-cost, scalable 6000-series aluminum conductors with superior combination of mechanical strength and electrical conductivity. By optimizing the thermo-mechanical processing of the aluminum alloy, a synergetic strengthening from precipitation and strain hardening mechanisms is achieved, while the EC loss is minimized. The formation of the strengthening Mg- and Si-rich phase is significantly improved by controlling the Mg and Si concentrations as well as adding inoculant elements to accelerate precipitation kinetics, thus also increasing the alloy’s strength. Two alloys stand out in particular: (i) Al-0.7 Mg-0.3Si-0.08Bi aged at 200 °C for 7 h (ultimate tensile strength = 426 MPa and EC = 52.7%IACS); and (ii) Al-0.7 Mg-0.3Si-0.01Sn aged at 200 °C for 4 h (ultimate tensile strength = 445 MPa and EC = 48.2%IACS).