Fractional‐order filters have received extensive attention from international scholars because of their greater design freedom and continuously stepped stopband attenuation rate. Based on genetic algorithm (GA), this paper proposes an optimum design approach for fractional‐order Chebyshev lowpass filters that meet design specifications. The fractional order and ripples attenuation of the normalized Chebyshev lowpass filter are calculated according to specifications, the integer order in the Chebyshev polynomial is replaced with the calculated fractional order, and then the fractional‐order Chebyshev polynomial is substituted into the magnitude response of the normalized Chebyshev lowpass filter along with the ripples attenuation to achieve the ideal response. The transfer function parameters of a fractional‐order filter are optimized using GA to make the magnitude response approximate the ideal response described above. This completes the optimized design of a fractional‐order Chebyshev filter that meets specifications. Given three different sets of design specifications, the fractional‐order Chebyshev filter designed using the proposed method is compared with one designed by another method in the literature. Finally, design examples are presented, stability analysis and Pspice simulations are performed, and an actual circuit is constructed to illustrate the effectiveness of the proposed method.

Ti film sputtered on flexible stainless steel substrate that rolled by 20-high Sendzimir Mill, was anodized in ethylene glycol bath in the presence of 0.5 wt.% NH4F and 3 vol.% H2O at a high voltage of 60 V. High-aspect-ratio porous-nanotube arrays (PNTAs) of TiO2 with the tubes length of 6.2 µm were quickly prepared from Ti film, at the high growth rate of 20.7 nm·s-1. Then the morphology and structure of PNTAs were characterized by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD), respectively. Finally, a DSSC with the photoanode of PNTAs exhibited a performance of Jsc= 2.40 mA·cm-2, Voc= 0.79V, FF = 0.57 and η = 1.08%.

Padding assisted roll-bending process is an advanced method to manufacture cylindrical thin-walled structure with variable thickness. A finite element model was established to study the deformation behavior of the padding assisted roll-bending process. In the numerical simulation model, aluminum sheet was selected as an elasto-plastic model, and nylon material was as an elastic model. The research results show that the radius of roll-bent thin-walled aluminum cylinder decreases with increasing of padding material’s stiffness, decreasing of the thickness ratio of nylon-to-metal and increasing of the roller stroke, and that an appropriate thickness compensation of padding material can improve the curvature consistency of cylindrical thin-walled structure with variable thickness.