Sample mean INDEX

Where Nvi is the observed number of particles per unit volume in the ith sample and "Nv is the arithmetic mean number of particles in n samples. (The index i refers to the ith sample in a set of n samples, and not to the particle size class). Maximum homogeneity is characterized by a minimum standard deviation other hand, special separating or agglomerating tendencies exist among the particles, the value of [Pg.33]

The refractive index of a medium is the ratio of the speed of light in vacuo at a given wavelength to the speed of light in the medium. Measurement is done by means of a suitable refractometer at a specihed temperamre for a particular sample. Refractive index is useful for identihcation of fats and the observation of progress in reactions during hydrogenation. 

The method described by Hirsch et al. (H4) uses intact male rats previously maintained on a low-calcium diet for 4 days. Standard and unknown preparations are injected subcutaneously into parallel groups of test animals, and after 1 hour blood samples are collected by cardiac puncture under ether anesthesia. The plasma calcium levels are measured, and the relative potencies of the preparations are calculated by standard statistical procedures. The mean index of precision of ten consecutive assays was reported as 0.23 0.025. 

Values obtained from the analysis of 25 natural samples. An increase in the mean index values was eorrelated with a decrease in both the Si/(Si + A1 + Fe ) and monovalent/total exchangeable cation ratios. 

We have now dropped the time index t in the ICA model, we assume that each mixture Xj as well as each independent component S/j is a random variable, instead of a proper time signal [3]. Without loss of generality, we can assume that both the mixture variables and the independent components have zero mean If this is not tme, then the observable variables Xi can always be centered by subtracting the sample mean, which makes the model zero-mean ... 

Source sampling of particulates requites isokinetic removal of a composite sample from the stack or vent effluent to determine representative emission rates. Samples are coUected either extractively or using an in-stack filter EPA Method 5 is representative of extractive sampling, EPA Method 17 of in-stack filtration. Other means of source sampling have been used, but they have been largely supplanted by EPA methods. Continuous in-stack monitors of opacity utilize attenuation of radiation across the effluent. Opacity measurements are affected by the particle size, shape, size distribution, refractive index, and the wavelength of the radiation (25,26). 

There exist two geometrically different varieties of these sites, which are referred to as B5 sites because both can be made to accommodate a nitrogen molecule, which is then coordinated by five atoms. They occur at steps on the (100) and (111) planes, and particularly on (110), (311), and other high-index planes. A later paper by van Hardeveld and van Montfoort (10) contains additional evidence showing that the B5 sites are indeed responsible for the infrared-active form of nitrogen adsorption, and also that the number of B5 sites in the sample can be estimated with fair accuracy from the intensity of the 2200 cm-1 band. This means that infrared study of nitrogen adsorption can give valuable information about the structure of the surface of metal particles. 

The relationship between the refractive index and the amount of dry substance content is well known for sucrose and is the basis for the degree Brix (°Brix) scale. It is arbitrarily set such that 1° Brix is equal to a concentration of 1% sucrose. In other words, the °Brix scale indicates the number of grams of sucrose per 100 g of solution. This relationship also holds for a large number of similar substances and finds extensive use in the food industry. For example, a reading of 40° Brix would mean that the sample contained 40 g of solid per 100 g of solution. 

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