Xian H. Li

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—this paper addresses on design of an optimal proportional integral derivative (PID) controller by applying Lyapunov approach. The optimal PID controller is acquired through minimizing an augmented integral squared error (AISE) performance index that contains control error and at least first order error derivative, and even may contain n orders error(More)
The S transform filtering methods are restricted by a fixed window function, so generalized S transform filtering methods are put forward. Firstly, generalized S transform whose time frequency resolution can be adjustable is achieved by altering normal S transform. The numerical implementation of generalized S transform is introduced later. Secondly,(More)
In order to get a certain fine structure of the seismic signal spectrum and improve the frequency resolution, this paper puts forward the frequency refining technology. Based on the complex modulation shift, digital low-pass filter, resample, complex FFT processing and frequency adjustment, this paper successfully achieves the ZFFT of the seismic signal,(More)
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