This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principl...This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principles, features and design steps of the threshold method. Rigrsure, heursure, sqtwolog and minimization four kinds of threshold selection method are compared qualitatively, and quantitatively. The wavelet analysis toolbox of MATLAB helps to realize the computer simulation of the signal noise reduction. The graphics and calculated standard deviation of the various threshold noise reductions show that, when dealing with the actual pressure signal of the oil pipeline leakage, sqtwolog threshold selection method can effectively remove the noise. Aiming to the pressure signal of the oil pipeline leakage, the best choice is the wavelet threshold noise reduction with sqtwolog threshold. The leakage point is close to the actual position, with the relative error of less than 1%.展开更多
This letter presents a new type of chaotic encryption system based on combined chaotic mapping pseudo-random number generator, Hash table, and elliptic curve. In this program, the elliptic curve algorithm is used for ...This letter presents a new type of chaotic encryption system based on combined chaotic mapping pseudo-random number generator, Hash table, and elliptic curve. In this program, the elliptic curve algorithm is used for the key distribution. After the linear transformation, the original chaotic sequence generated by drive system will be combined to chaotic mapping, converted to an encryption key sequence and constructed as Hash table for message authentication. The communication experiment used in the letter proves that the combination of combined chaotic encryption and conventional encryption is safe, feasible, and easy to implement by software.展开更多
文摘This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principles, features and design steps of the threshold method. Rigrsure, heursure, sqtwolog and minimization four kinds of threshold selection method are compared qualitatively, and quantitatively. The wavelet analysis toolbox of MATLAB helps to realize the computer simulation of the signal noise reduction. The graphics and calculated standard deviation of the various threshold noise reductions show that, when dealing with the actual pressure signal of the oil pipeline leakage, sqtwolog threshold selection method can effectively remove the noise. Aiming to the pressure signal of the oil pipeline leakage, the best choice is the wavelet threshold noise reduction with sqtwolog threshold. The leakage point is close to the actual position, with the relative error of less than 1%.
文摘This letter presents a new type of chaotic encryption system based on combined chaotic mapping pseudo-random number generator, Hash table, and elliptic curve. In this program, the elliptic curve algorithm is used for the key distribution. After the linear transformation, the original chaotic sequence generated by drive system will be combined to chaotic mapping, converted to an encryption key sequence and constructed as Hash table for message authentication. The communication experiment used in the letter proves that the combination of combined chaotic encryption and conventional encryption is safe, feasible, and easy to implement by software.
