Work summary of week 4

In the last week, we obtained the frequency f of the signal by fast fourier transform (fft) method. However, the resolution ratio of the frequency is 10kHz. This is because resolution ratio equals to sampling frequency (2*10^9Hz) divided by sampling points(2*10^5). Thus, we regarded f as 40kHz. In week 2, the smooth Q-U Lissajous was achieved. That graph contains about three and a half periods of data, so there are three curves mixed with each other. What we want is the Q-U Lissajous figure with just one period, so we modified the program. If we use the former 57000 data points to plot the graph, it seems like a closed curve for one period as shown below.

 

 

Next, the total work of one period, i.e. the area surrounded by the curve, could be calculated by the following equation,

According to the above equation, we wrote a program to compute the work and the result is 0.0016J. Then, the discharge power of the DBD plasma reactor could be gained according to

So far, the most important part of the project was completed. To make it more impeccable, some characteristics of the input signals should be showed. In week 1, the waveform of the applied voltage and the capacitor voltage had been displayed. Thus, we wrote a program to gain the maximum value, minimum value, mean value, rms value and peak-to-peak value of the input signals. Matlab has the ready-made functions of these characteristics, so it was easy to compile the program.  

 

Finally, to display the information intuitively, it was essential to create an interface to integrate all the results and figures together. This could be done by GUI of Matlab, but we had never used it before. Hence, further work should be done to learn how to use GUI to make the interface. The main task of the 5^th week is to show all the information on one interface.