Coefficient of uniformity

Ki. K2 coefficients of uniformity of cellular saturation density of gase phase... 

The concept uniformity of a material, however, has the following quantitative definition the coefficient of uniformity of a material, from the point of view of probability, is the ratio of some property (technical characteristic) of the material at a given value of probability (for a known integral distribution curve) to the arithmetic mean value of this property. 

The distribution of some important technical characteristics of plastic foams, e.g. stretch, is closer to the Weibull than to the Gaussian distribution due to nonuniformity . Kozlov obtained the analytical expression for the coefficient of uniformity K2 for the Weibull distribution and used it to estimate the uniformity of phenolic foams. 

Hence, Eq. (6) determines the coefficient of uniformity throu the parameters of the WeibuU distribution. 

It should be noted that up to now, quantitative estimates of the uniformity of gas-filled plastics have not been carried out, although the importance of this concept for the estimation of the morphology of foamed plastics is obvious. Indeed, for researchers and technologists the quantitative determination of the uniformity of foams should become one of the basic criteria of the quality of articles, along with other morphological parameters. On the other hand, for theoretical calculations, it should be remembered that the coefficient of uniformity is a brutto characteristic of foam heterogeneity and incorporates the total non-uniformity of the dis-... 

Awareness of attributes of particle size distribution (i.e. percentage passing through a 0.075 mm sieve, d- o, d Q and djo), either coefficient of uniformity, Cu, or coefficient of curvature, Cq, as well as plasticity index (PI), is required for the classification of soils in some subgroups. 

Given the angularity and coefficient of uniformity, an estimate of the minimum and maximum void ratio of a sand can be made based on Figure C.l. (Youd 1973). 

The findings of Lafleur (1999) and the recommendations of Holtz et al. (1997) were combined in the design approach pubUshed by the Canadian Geotechnical Society (CFEM, 2006). The threshold value for the application of the approach by Lafleur for widely graded soils was taken to Cu = 8 (instead of Cu = 6 in the original proposal) and for coefficients of uniformity 4 < Cu < 8 opening sizes O90 > I dgS re allowed (Table 12.1). 

Figure 12.2 Normalized retention criteria O dso versus coefficient of uniformity Cu including...

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