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In seismic exploration, seismic data usually contain anomalous amplitude noise whose high energy may affect the results of subsequent processing steps. In industry, this kind of noise is generally suppressed using the anomalous amplitude attenuation (AAA) method. The AAA method essentially suppresses abnormal amplitude noise using a median filter in the time-frequency domain. This makes its performance heavily dependent on the parameters, especially the window width of the median filter. Thus, we propose an improved anomalous amplitude attenuation (IAAA) method based on deep neural networks. The IAAA method contains two steps. In the first step, deep neural networks are used to detect the locations and the widths of noise regions. In the second step, the noise information (locations and widths) obtained at the previous step is exploited to apply the AAA method with more appropriate parameters to each noisy region. Compared with the conventional AAA method, the IAAA method can suppress the noise more effectively and preserve signals better. The experiments on both synthetic data and field data demonstrate that our method outperforms the conventional AAA method.

An improved key expansion method is proposed to improve the security performance in AES key expansion. There is large difference of operation time between Mixcolumns and Inverse Mixcolumns, we propose the simplest form of MixColumn and InvMixColumn operation on finite field \(GF(2^{N})\) which consumes same computing resources in the process of encryption and decryption. In terms of the defection of RSA operation efficiency, traditional double prime number is replaced by four prime number, Chinese remainder theorem combined with Montgomery modular multiplication is also presented to optimize modular exponentiation. On this basis, we adopt message digest, digital signature, digital envelope and other technologies to build a mixed encryption system which encompasses convenient key management and high-efficiency encryption and decryption, combined with the advantages of AES and RSA. The experimental results show that optimized algorithm has high speed and feasibility.