Calculating a mean

Step 5. Calculate a mean diameter in preparation for calculating the compressor speed. Use Equation 6.18. 

In this calculation a mean area of surface might have been used with sufficient accuracy. It is important to note the great importance of the scale terms which together form a major part of the thermal resistance. 

Possibly, the most difficult aspect of determining particle size is selecting initially the correct or relevant definition and then calculating a mean or average diameter to represent the complete bulk solid. To some extent, this will depend on the following. 

In the present case, which is concerned with power consumption per unit mass, the mass mean diameter is probably of the greatest relevance. For the purposes of calculation a mean value of 4.0 mm will be used, which agrees with the value obtained by Bond s method. 

In a tube we use the volumetric flow rate, Q, to calculate a mean velocity along the tube and we have... 

Statistics frequently involve calculations of the mean of a sample. In order to be able to calculate a mean, there must be at least two values present. For this reason, when describing sample size, the term n— 1 is often used instead of the actual number. One of the sample points must be present in order that each of the other points can be used in the mean calculation. In other words, the size of the freely chosen sample must always be one less than are actually present. 

One person suggested that maybe the best thing in calculating a mean is to exclude less than figures. Dr. Mitchell concurs "That s correct. In a majority of cases the less than values are beyond the limit of determination and are statistically supposedly invalid."... 

Now, we can calculate a mean volume element that a dye occupies in the zeolite crystal, and if we consider this volume element as a cube, we can calculate the length of the cube. If we use a 1 1 mixture of donor D and acceptor A, this length is approximately the mean distance between D and A ... 

Dilution by merging rivers. The rate constant is given by Eq. 24-69. Of course, the discharge Q(t) increases stepwise along the Rhine, not continuously. However, we still can calculate a mean dilution rate, dj, by solving Eq. 24-68 for constant km ... 

The use to the described scheme to calculate a mean value in equation (7.1.40) leads to the expresion... 

Our microscopic formalism cannot give the distribution function over aggregate sizes, but having calculated a mean number of particles within aggregate, equation (7.2.8), we can assume approximate validity of the Poisson distribution (for the moderate aggregation efficiency)... 

The mechanism of deposition in the size range 0.1-1 /tm, and the appropriate vg values, have been the subject of some dispute. Sulphate particles in the urban and suburban atmosphere have median diameters of about 0.5 /um (Heard Wiffin, 1969 Whitby, 1978). Using the results of Fig. 6.9, and weighting vg according to the mass of sulphate in various size ranges, Garland (1978) calculated a mean value of vg for sulphate aerosol of 1.0 mm s-1. Nicholson Davies (1987) measured the profile of SO4- concentrations, and also wind speed, above agricul-... 

The QDC calculates a mean and the covariance for each class, allowing the classifier to find more accurate discriminative functions. Each sample is assigned to the class with the highest log-likelihood calculated following Equation (7.2), with the class mean /x and the class covariance . 

Now, one can calculate a mean displacement R of the particle after N steps... 

Sometimes when comparing two methods in analytical chemistry we are unable to obtain true replicates of each specimen or aliquot, due to limited availability of the test material or the requirements of the analytical method. In these cases, each test object or specimen has to be treated independently for the two methods, i.e., it is not possible to calculate a mean and standard deviation for the samples as each... 

Mathematically, it is perfectly possible to calculate a mean or a median among these score changes and these are shown on Figure 2.4. However, neither indicator remotely encapsulates the situation. The mean (—0.77) is particularly unhelpful as it indicates a value that is very untypical - very few patients show changes close to zero. We need to describe the fact that, in this case, there are two distinct groups. 

By this technique an average value is measured. From this the authors calculated a mean amplitude 02 = 18.3° in H20 HF which is lower than the corresponding values for rare gas atom HF complexes Ar HF, 02 = 41.1° and Kr HF, 02 = 39.2°49,50). As expected, hydrogen bonding introduces some rigidity into the complex However, the isotope effect on 02 in H20 HF is not yet clear48 . 

When an observable value was missing, no collocated difference was obtained for that observable. However, to calculate a mean value if one of the observables was missing, the valid collocated measurement was taken as the mean. For a week which contained one or more missing daily samples the derived weekly and the corresponding measured weekly samples were discarded from the comparison only if the precipitation of the missing daily sample(s) accounted for more than 20% of the week s total. This was done to maximize the number of data points and the power of the statistical tests. 

Figure 8.6). Bennett (1983) calculated a mean PCB exposure of 24)ag/day for a US adult calculated from food concentrations and food intake rates measured in the US in the early to mid-1970s. He compared this with exposures of 5-100 pg/day estimated by WHO in 1976. About 10 years later, Davies (1988) estimated an adult PCB intake of 0.09)ag/day from a... 

When scanning in the absorbance mode the total error is, according to Jork 54), 2-4% (variation coefficient), in the fluorescence mode < +1%. Grimm 55) has calculated a mean variation coefficient of 2.5% from numerous data in the literature and from his own analyses the variations lie between 0.7 and 5.2% the statistical data relate to the total analysis with manual evaluation. 

In this exercise, we have learned to calculate a mean, using both the built-in Excel AVERAGE function and a formula of our own design. In Chapter 6, we will use STDEV and other functions to complete our analysis of the data from the gravimetric determination of chloride that we began in Chapter 2. You may now close Excel by typing File/Exit or proceed to Chapter 6 to continue with the spreadsheet exercises. 

With respect to response time we want to address both static, long-term service properties and dynamic, short-term characteristics. Static properties are usually determined by the complexity of the task performed by the service, the capacity of the server and the network between client and server. They are usually accounted for by calculating a mean value, in this case the average response time. 

For complex or critical calculations, a means should be provided for recording the result. 

Sea and the Levantine Basin. The deep waters of these basins used to be very homogenous in temperature and salinity displaying only small horizontal gradients (Fig. 4.2 Schlitzer etal., 1991). Roether and Schlitzer (1991) computed an annual mean formation rate of 0.3 Sv for LDW formed in the Adriatic. Using freon and tritium measurements, Roether etal. (1996) calculated a mean residence time of LDW in the eastern basin which was 50-80 years. 

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