| We know that the particles do bad to the global climate, the quality of industrial production and especially the health of human. So, it is important to pay attention to the concentration of particles in the air. The single particle scattering method is widely employed due to fast, high precision, non-intrusive and suitable for on-line measurement. At the present time, our central tasks are to enhance the precision of measurement and investigate the character of the pulse distribution.It's founded that the pulse is a log-normal distribution no matter it follows with the time or the pulse height. In this paper, we research the log-normal function from many aspects. And then, we conclude that the productive property is a character of log-normal function. It means that the product of two independent log-normal variables still is a log-normal variable. But we can not say that this function has the character of summative property, because we just can use another log-normal function approach the distribution of the sum of two independent log-normal variables on some condition.In this paper, we also use two methods:the numerical simulation and the academic method to prove that the superposition of two log-normal distribution figures is still a log-normal distribution figure. This explains why sometimes the dates are log-normal distribution. In addition, when the mass increases, the mean value of logarithm increases, and finally the discrete value of logarithm increases. So, we should find the relationship between the mean value of logarithm and the discrete value of logarithm, and we get that--- it is a exponential relationship. It supplies some warrants for designing.Because of noises of the apparatus, the pulse will be inspired to a higher signal-shelve, when the highest shelve is confined, we can know the biggest pulse signal which represents the biggest particle diameter. The detailed procedure will be presented in this paper. It can supply some warrants for limiting the noise. |
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