Collect Online Data for the Whole Operation Cycle

2 COLLECT ONLINE DATA FOR THE WHOLE OPERATION CYCLE 

The normal distribution is the most commonly known as it represents the typical variation pattern in the process industry Most data are close to the average representing the normal operation while a small fraction of data corresponds to campaign operation or turndown operation. Therefore, the normal distribution is widely used to describe variations of real data that cluster around the single mean value as a simple model for complex phenomena. The normal distribution can be described by a probability density function as 

DETERMINE THE TRUE BENEEIT FROM PROCESS VARIATIONS 

FIGURE 21.3. Probability density function of normal distribution. 

The mean determines the location of the peak of the distribution in relation to the y-axis. If the mean is zero, the central line of the profile overlaps with the y-axis. The standard deviation determines the width of the distribution profile. A large a implies a wide variation featuring a short and fat profile, while a small a indicates a narrow variation corresponding to a long and thin profile. 

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