多孔阳极氧化铝形成过程的研究

研究了纯铝在3种不同电解液中的阳极氧化过程，通过分析阳极氧化曲线上不同阶段氧化膜的SEM照片，探讨了铝阳极氧化阻挡层的形成、阻挡层向多孔膜的转化、多孔膜的生长的过程。结果表明：多孔氧化膜不但产生于酸性溶解的电解液中，而且在非溶解性的电解液中也可以产生。提出了在阻挡层的生长过程中，氧气的析出是造成多孔产生的新观点，并从不同电解液角度进行了论证。不同的电解液体系中，氧气的析出电压不同，多孔氧化膜的孔径与电解液的种类有关。     

A Blind Adaptive Jamming Canceller Using Antenna Array for GPS Receiver

Traditional beamformers need to know the incident angle of the desired signal leading while its ability to handle interference is limited. In this paper, the constrained steer vector of linearly constrained minimum-variance (LCMV) beamformer is modified to make sidelobe null to direction of powerful jammer. In addition, the state-space concept is used to describe the anti-jammer filter, and Kalman filter algorithm is deduced by building the observation model and measurement equation. The new method is more efficient on computation and more robust to survive environment with large scale variation in interference strength. Finally, simulation results shows that the new approach can form the null with its depth in proportion to power in direction of jammer, and has steady convergence process. The novel method can effectively improve the signal-to-jammer-plus-noise power ratio (SJNR) of GPS signals to make the correlation peak easy to track.     

Anti-Jamming with Adaptive Arrays Utilizing Power Inversion Algorithm

The convergence rate of the power inversion （PI） algorithm is quite sensitive to the power of the interference with the used fixed parameters in the PI algorithm leading to degradation of its ability to handle interference. This paper presents a normalized PI algorithm that traces the stochastic characteristics of the interference. The algorithm adaptively adjusts the recursive step size to determine the constrained optimized parameters for the Iowpass filter. Simulations show that the normalized PI algorithm achieves faster convergence and produces deeper nulls. The algorithm makes GPS receivers more robust in environments with large variations in the interference strength.