This paper presents an analysis, informed by socio-technical transitions theory and the socially derived concept of automobility, of the impact of the SARS-CoV-2 virus and resulting COVID-19 pandemic on automobility in Europe. The paper argues that the concept of a pervasive, sudden, and powerful crisis has not previously be explored in the socio-technical transitions literature. The strong behavioural changes in physical and virtual mobility associated with the pandemic are argued to be particularly significant, representing a ‘living lab’ in which to explore the possibilities for disintegrating the boundaries of the automobility system, thereby breaking the enduring structures and practices that have enabled automobility to remain largely unchallenged in the policy arena. Change processes previously underway in the automotive industry and in automobility are not impacted equally by the pandemic. We present initial evidence that mobility sharing will reduce, while the acceptance of electric cars will increase. However, it is also concluded that the hegemony of private automobility is not in itself threatened by pandemic outcomes.

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Considering the importance of line fundamental impedance from the inverter to the point of common coupling (PCC) in microgrids, this study analyzes the influence of fundamental impedance on system stability. Line fundamental impedance values not only apply to decoupled droop control, which can realize accurate control between active and reactive power, but also regulate the droop coefficient to eliminate system circulation, realize power sharing, and improve system stability when a multi-distributed generation system operates in parallel. Moreover, the PCC can sense grid fault on the basis of variations in fundamental impedance. A novel fundamental impedance identification method that adopts a constant power control strategy by varying the active and reactive powers in the grid-connected mode is proposed. In addition, the proposed method has online real-time calculation capability. This strategy has been tested in simulation and in experiments by using a scaled laboratory prototype. Simulation and experiment results verify the accuracy of the proposed scheme.

The Hastelloy X (HX) nickel-based superalloy is increasingly applied in the aerospace industry because of its exceptional combination of oxidation resistance and hightemperature strength. The addition of nanoscale ceramic reinforcements to the HX alloy is expected to further improve its mechanical and thermophysical performance.The research challenge is to manufacture HX nanocomposites using additive manufacturing (AM) technologies, particularly selective laser melting (SLM), which has been used successfully to produce other nanocomposites. This paper systematically studies the microstructure and tensile performance of HX-3 wt.% TiC nanocomposite fabricated via SLM and explores the effects of TiC nanoparticles on hot-cracking elimination and strength enhancement. The findings reveal that the addition of 3 wt.% TiC nanoparticles resulted in (1) an extra 73 J/mm 3 laser-energy density needed to manufacture nearly full-density nanocomposite samples and (2) intergranular microcrack elimination due to the significant increase in grain boundaries induced by the grain refinement. The results showed a 17% increase in yield strength, while the elongation to failure was not significantly reduced. The results from the microstructure examination suggest that the strengthening mechanisms of load bearing and enhanced-dislocation density were the most pronounced mechanisms in the SLMfabricated nanocomposite. These findings offer a promising pathway to strengthen mechanical performance by addressing the hot-cracking issue in the AM of nickelbased superalloys that suffer from cracking susceptibility. The results can also help to accelerate the uptake of AM in high-performance and defect-free superalloys for various applications.

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The nickel-based Hastelloy X (HX) superalloy is widely applied in the aerospace industry because of its exceptional oxidation resistance and various beneficial properties at high temperatures. HX-based nanocomposites manufactured by additive-manufacturing processes based on powder-bed fusion, such as selective laser melting (SLM), are expected to further enhance the material's mechanical and thermophysical performance. This paper systematically studies the effects of TiC nanoparticle content on the microstructure and tensile performance of SLM-fabricated HX nanocomposites. The results reveal that the microcracking that formed in pure HX was successfully eliminated in the fabricated nanocomposites when 1 wt.% and 3 wt.% TiC nanoparticles were introduced. The fabricated HX-3 wt.% (HX-3) TiC nanocomposite showed several TiC clusters and a much higher pore-volume percentage (0.15%) compared to the HX-1 wt.% (HX-1) TiC nanocomposite, in which this percentage was determined to be 0.026%. Compared to SLM-fabricated pure HX alloy, the HX-1 nanocomposite exhibited over 19% and 10% improvements in ultimate tensile strength and elongation to failure, respectively. A further increase in TiC content to 3 wt.% was not found to further enhance the tensile strength but did result in a 10% loss in elongation to failure in HX-3 nanocomposite. These findings offer a promising pathway to employ SLM to manufacture both high-strength and high-ductility materials through the careful selection of nanoparticle materials and their content.