Abstract-In this paper, a reduced-rank scheme with joint iterative optimization is presented for direction of arrival estimation. A rank-reduction matrix and an auxiliary reduced-rank parameter vector are jointly optimized to calculate the output power with respect to each scanning angle. Subspace algorithms to estimate the rank-reduction matrix and the auxiliary vector are proposed. Simulations are performed to show that the proposed algorithms achieve an enhanced performance over existing algorithms in the studied scenarios.

Oxidized sodium alginate is a handily modifiable polysaccharide owing to the pendant aldehyde groups which can form dynamic covalent bonds with amines, acylhydrazines, etc., providing oxidized sodium alginate-based hydrogels with stimuli-responsive properties. However, due to the stiffness and, in particular, the hydrophobicity of sodium alginate dialdehyde at low pH, the mechanical performance and pH stimuli responsiveness of oxidized sodium alginate-based hydrogels are still strictly limited. Herein, we report a new strategy to build an injectable, dual responsive, and self-healing hydrogel based on oxidized sodium alginate and hydrazide-modified poly(ethyleneglycol) (PEG). The hydrazide-modified PEG, referred to as PEG-DTP, acts as a macromolecule crosslinker. We found that the presence of PEG-DTP reduces the hydrophobicity of oxidized sodium alginate at low pH so effectively that even a pH-induced reversible sol-gel transitions can be realized. Meanwhile, the disulfide bonds in PEG-DTP endows the hydrogel with the other reversible sol-gel transitions by redox stimuli. In particular, due to the softness of PEG-DTP chains, mechanical performance was also enhanced significantly. Our results indicate we can easily integrate multi-stimuli responsiveness, injectability, and self-healing behavior together into an oxidized sodium alginate-based hydrogel merely by mixing an oxidized sodium alginate solution with PEG-DTP solution in certain proportions.

A general framework of finite-SNR diversitymultiplexing tradeoff (DMT) is formulated to evaluate the impact of imperfect channel estimation in two-way amplify-andforward (AF) relaying systems over Nakagami-m fading channels. Imperfect self-interference cancellation and signal detection are performed at both sources due to channel estimation errors. The overall outage probability (OOP) is obtained and then the finite-SNR DMT is derived in the presence of channel estimation errors. Furthermore, the asymptotic and limiting behavior expressions of the finite-SNR DMT are also evaluated adequately. Numerical results verify the theoretical analysis and show that at realistic SNR and channel estimation quality, the DMT is significantly lower than the asymptotic result.Index Terms-imperfect channel estimation, two-way amplifyand-forward (AF) relaying, overall outage probability (OOP), finite-SNR diversity-multiplexing tradeoff (DMT).

Selenium (Se) has received extensive attention as the most competitive cathode material for next generation high‐energy batteries. However, the shuttle effect of polyselenide and volume change lead to inferior electrochemical properties. To solve these issues, a porous bamboo‐derived carbon (PBC) with abundant meso/micropores is prepared as a framework to effectively encapsulate elemental selenium. For Li–Se batteries, Se/PBC electrode delivers an outstanding capacity of 509 mAh g−1 after 200 cycles at 0.2 C (1 C = 675 mA g−1) with a low capacity fade of 0.036% per cycle. The Se/PBC composite also reveals a satisfied electrochemical performance for Na–Se batteries with an excellent capacity of 409 mAh g−1 after 200 cycles at 0.2 C. Moreover, Se/PBC electrode also presents excellent long‐term cycle performance and rate performance at 15 C for Li–Se batteries and 10 C for Na–Se batteries. The outstanding properties are attributed to the specific 3D structure and high conductivity of PBC, which significantly inhibits the shuttle effect and enhances the reaction kinetics. Herein, not only the great application potential of bamboo in energy storage systems is demonstrated, but also an effective approach and low‐cost strategy for improving the performance of lithium/sodium–selenium batteries is offered.

The effects of gamma irradiation on the resonant frequency of a surface-micromachined polysilicon doubly clamped resonator are examined by a laser Doppler vibrometer. The resonant frequency of the resonator decreases by 2.1% for the 500-μm-long beam and 2.7% for the 300-μm-long beam after 32-krad (Si) gamma irradiation. The residual strains of the surface-micromachined polysilicon beams, which are estimated through the change of the resonant frequency, decrease by 2.7% and 5.4% for the 500-and 300-μm-long beams, respectively. Radiation effects of the polysilicon beams have been explained in terms of injection annealing.[2011-0152]

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