Study on center frequency of tomato water stress based on virtual instrument

In this paper,developed are a method and correspondent software for calculating formation permeability from the center frequency shift and travel time delay in direct Stoneley wave.

This paper derives the universal formulas for three characteristic parameters, center frequency, gain of center frequency and quality factor of bandpass filter, calculates the theoretical values of the three characteristic parameters; analyzes the effects of center frequency migration of bandpass filter on logs.

The result shows the percent determination is increased along with force and compared with the median frequency and found the relation of them.

To acquire the median frequency from surface myoelectric signal spectrum,we designed a measuring system which could display the time course of the median frequency in real time so as to monitor local muscle fatigue, and used classic fast Fourier transform (FFT) algorithms to perform the estimation of the median frequency.

The main method is combined the square wave circuit with the switch capacitor filter MAX268BCNG to realize the automatic tracking filtering at the central frequency,which is form1Hz to 15Hz.

The central energy variation of electron bunch is obtained by measuring the central frequency, which is in agreement with the result from measuring closed orbit and horizontal dispersion function.

The key technique of this new filter is how to achieve the extreme narrow band-pass width and a slight deviation of central frequency.

Relation between changes of sEMG s mean frequency and changes of blood lactate content with different loads during exercise;