Bioinspired hydrogel with both outstanding actuation and conductive properties still remains challenging. Here, we use a simple and universal method to fabricate an octopus-tentacle inspired multifunctional gradient hydrogel with both...

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This paper presents the design and control of an advanced unidirectional DC/DC Modular Multilevel Converter (MMC) which enables the integration of off-shore windfarms with the High-Voltage Direct Current (HVDC) transmission system. The proposed converter consists of a single-phase MMC inverter, coupled with series-connected rectifier modules through a medium frequency transformer of multiple secondary windings. The modularity feature of the proposed converter enables scalability for different voltage levels. In addition to the galvanic isolation, the transformer also provides stepping gain to the output voltage. The proposed converter shows superior performance in terms of efficiency, losses and devices utilization, when compared with the most competitive unidirectional cascaded DC/DC converters such as input series output series (ISOS) and input parallel output series (IPOS). Furthermore, unlike the conventional d-q control method, which involves multiple transformations, this paper employs a simple proportional resonant (PR) control strategy that directly acts on the AC output of the MMC, under the stationary reference frame. The analytical design along with the simulation and experimentally validated results, confirmed the excellent performance of the proposed converter.

Simple, low-cost, and high-performance atmospheric water harvesting (AWH) still remains challenging in the context of global water shortage. Here, we present a simple and low-cost macroporous hydrogel for high-performance AWH to address this challenge. We employed an innovative strategy of pore foaming and vacuum drying to rationally fabricate a macroporous hydrogel. The hydrogel is endowed with a macroporous structure and a high specific surface area, enabling sufficient contact of the inner sorbent with outside air and high-performance AWH. The experiments demonstrate that macroporous hydrogels can achieve high-performance AWH with a broad range of sorption humidity [relative humidity (RH) from 100% to even lower than 20%], high water sorption capacity (highest 433.72% of hydrogel’s own weight at ∼98% RH, 25 °C within 60 h), rapid vapor capturing (the sorption efficiency is as high as 0.32 g g–1 h–1 in the first 3 h at 90% RH, 25 °C), unique durability, low desorption temperature (∼50 °C, lowest), and high water-releasing rate (release 99.38% of the sorbed water under 500 W m–2 light for 6 h). The results show that this macroporous hydrogel can sorb water more than 193.46% of its own weight overnight (13 h) at a RH of ∼90%, 25 °C and release as high as 99.38% of the sorbed water via the photothermal effect. It is estimated that the daily water yield can reach up to approximately 2.56 kg kg–1 day–1 in real outdoor conditions, enabling daily minimum water consumption of an adult. Our simple, affordable, and easy-to-scale-up macroporous hydrogel can not only unleash the unlimited possibilities for large-scale and high-performance AWH but also offer promising opportunities for functional materials, soft matter, flexible electronics, tissue engineering, and biomedical applications.

In an induction motor with broken rotor bars, stator currents contain fault-related components. The fault information propagates to voltages when the motor is in a closed-loop control. The control has an effect on the c u r r e n t sa n dv o l t a g e s .R e l y i n gs o l e l yo nt h ec u r r e n t so rv oltages is difficult to obtain an accurate detection and quantification of the fault. A new online diagnosis method, which takes both currents and voltages into consideration, is proposed in this study. A fault severity factor is proposed to evaluate the extension of the fault, which is almost independent of the control parameters. Furthermore, the me t h o dc a nb ea p p l i e dt od i f f e r e nt control strategies. The effectiveness and robustness of the proposed method have been validated by experimental results.