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The aerodynamic properties of a pantograph that is under consideration for application on Korean high-speed trains are experimentally investigated. The selected experimental models were one-quarter scale pantographs (a double-arm pantograph, single-arm pantograph and a periscope pantograph) with either a rectangular panhead or a panhead with an optimized streamlined shape. To increase the performance and the robustness of the pantograph, the drag coefficient and the fluctuation of the lift coefficient along the angle of attack are simultaneously minimized. In order to confirm the aerodynamic enhancement of the pantograph due to the optimized panhead, the aerodynamic forces are compared with those of a pantograph with a rectangular panhead. To investigate the aerodynamic force distribution of a pantograph, the aerodynamic forces of the lift and drag of the pantograph are measured in wind tunnel tests and analyzed in terms of the pantograph’s components. In addition, wake flows are examined based on variations of the shape of the panhead.

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The detection of ions is of critical importance for environmental, industrial, and physiological applications, where sensitive and disposable ion sensing is still challenging. Herein, we present a sensitivity-tunable ion-sensing platform based on reverse electrodialysis, which is suitable for convenient and sensitive on-site analysis of various ions. It is revealed that this sensing system does not require any external power supply, and the sensitivities can be modulated by altering the number of stacks, possibly higher than the theoretical limitation, the Nernstian slope. The sensing system is integrated with a multicolor detection system via the introduction of polyaniline as a reporting material, which enables direct quantitative analysis based on a continuous color change gradient observable with the naked eye. Overall, the adopted approach by introducing reverse electrodialysis represents remarkable progress toward self-powered and disposable ion sensors with high and easily tunable potentiometric sensitivity.