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The interplay between timeliness and rate efficiency is investigated in packet erasure broadcast channels with feedback. A scheduling framework is proposed in which coding actions, as opposed to users, are scheduled to attain desired tradeoffs between rate and age of information (AoI). This tradeoff is formalized by an upper bound on AoI as a function of the target rate constraints and two lower bounds: one as a function of the communication rate and one as a function of the arrival rate. Simulation results show that (i) coding can be beneficial in reducing AoI in the regime of moderate arrival rates even without rate constraints and the benefit increases with the number of users, and (ii) AoI increases with both the target rate constraint and the arrival rate when either is kept fixed, but decreases with them when they are set to be equal.

Aqueous flow batteries are considered very suitable for large‐scale energy storage due to their high safety, long cycle life, and independent design of power and capacity. Especially, zinc‐iron flow batteries have significant advantages such as low price, non‐toxicity, and stability compared with other aqueous flow batteries. Significant technological progress has been made in zinc‐iron flow batteries in recent years. Numerous energy storage power stations have been built worldwide using zinc‐iron flow battery technology. This review first introduces the developing history. Then, we summarize the critical problems and the recent development of zinc‐iron flow batteries from electrode materials and structures, membranes manufacture, electrolyte modification, and stack and system application. Finally, we forecast the development direction of the zinc‐iron flow battery technology for large‐scale energy storage.

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