A two-dimensional metallic SnB monolayer as an anode material for non-lithium-ion batteries.

Na-, K- and Mg-ion batteries (NIBs, KIBs and MIBs) have drawn considerable interest due to their high abundance and excellent safety. However, the lack of high-performance anode materials is a major obstacle to its development. A metallic SnB planar monolayer is predicted by using the two-dimensional global minimum structure search method of swarm intelligence. Based on first-principles calculations, we proved that the metal SnB monolayer has high binding energy and excellent dynamical, thermal and mechanical stability. It is worth noting that the SnB monolayer has several stable adsorption sites for Na-, K- and Mg-ions, so it has a high theoretical capacity of 620.93, 517.44 and 620.93 mA h g-1, respectively. For Na-, K- and Mg-ion batteries, the low diffusion barriers of the SnB monolayer are 0.22, 0.07 and 0.68 eV, and the low average open circuit voltages are 0.42, 0.49 and 0.23 V, which ensure long service life and fast charging in practical applications. In addition, it is proved that the SnB monolayer maintains excellent conductivity and stability during the charge-discharge process. The results show that the SnB monolayer offers innovative advantages for the development of new two-dimensional planar structures that further advance the development of anode materials for metal ion batteries.

[Research progress on medical body area network].

This article introduces the present development situations and research progress on key technologies of BAN. After a review on BAN propagation channel modeling, transmission technologies and multiple accessing methods, the technical difficulties as well as the focus of study both at home and abroad are discussed. We further put forward the new appealing technologies and their practical feasibility.

Optimal waveforms design for ultra-wideband impulse radio sensors.

Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations.