Step count

Step Count Methods These methods, used for order-of-magnitude estimates, are based on the definition of the functional units required to carry out the process. A functional unit is a signifi-... 

In general, the step count method of estimation can be apphed to any special situation to derive a model equation for that particular industry or group of processes. 

Figure 4.35 Reduced synthesis tree for Khorana-Todd synthesis of co-enzyme A. Step counts are shown in parentheses.

Figure 4.39 Reduced synthesis tree for Novartis synthesis of discodermoiide. Step counts are shown within parentheses.

Step counting estimating methods provide a way of making a quick, order of magnitude, estimate of the capital cost of a proposed project. 

A number of workers have published correlations based on a step counting approach Taylor (1977), Wilson (1971). These and other correlations are reviewed and compared in the Institution of Chemical Engineers booklet, IChemE (1988). 

Clearly, step counting methods can only, at best, give a very approximate idea of the probable cost of a plant. They are useful in the conceptual stage of process design, when comparisons between alternative process routes are being made. 

Step-counting methods are based upon a number of processing steps or functional units. The concept was first introduced by H. E. Wessel, Chem. Eng., 1952, p. 209. Subsequently, R. D. Hill, Petrol. Refln., 35(8) 106-110, August 1956 P C. Zevnik and R. L. Buchanan, Chem. Eng. Progress, 59 2) 70-77, Pebruary 1963 and J. H. Taylor, Eng. Process Econ., 2 259-267, 1977, further developed the stepcounting method. 

Overall MCRs are a big step towards the ideal synthesis, which, according to Wender et al. can be measured by parameters such as the step count, overall yield, selectivity, cost, scale, resource requirements, waste stream, development time, execution time and personnel [8], The discovery of novel IMCRs are explained and several conceptually different approaches towards this goal, with an emphasis on our recent contributions in this area are shown. 

Your goal would be to increase the number of steps taken each day to ten thousand. Remember that all steps count, whether you re out for a brisk walk or simply climbing a flight of stairs at home or at work. Wearing that pedometer acts as a reminder and a motivator. Most men and women find it fun to see each day s... 

The code has taken about Iwork(21) steps (counted as Iwork(ll) — Iwork(lO)) on this call. If you want to continue, set Info(l)=l in MAIN and call DDAPLUS again another Iwork(21) steps will be allowed. 

Step-count methods such as Bridgewater s method were developed for chemical plants and do not extend well to other types of manufacturing. For large-scale production (>500,000 pieces per year) a rule of thumb is... 

The experimental pattern was collected with a 0.02° step from 7 to 50° 20 and a counting time of 60 sec/step, and from 50 to 69° 20 with a counting time of 90 sec/step. The high Bragg angle intensities were scaled to the 60 sec/step counting time for all calculations. The following initial parameters were used in the model completion and refinement ... 

Every effort should, of course, be made to measure line positions precisely. If one aims at a precision of 3 parts in 100,000, equivalent to +0.0001 A in the lattice parameter, then Eq. (11-1) shows that the 29 position of a line at 29 = 160° must be measured to within 0.02° and lower angle lines even more closely. It is better to determine the line profile by step-counting with a scaler than by chartrecording with a ratemeter. In parameter measurements it is usual to take the 29 value of maximum intensity as the line position strangely, curve-fitting techniques for establishing line position, which are standard in the field of stress measurement (Sec. 16-4), are practically never used. 

Atom environment descriptors are calculated by a two-step procedure in the first step, the Sybyl atom types are assigned to all heavy atoms in the second step, count vectors of the atom... 

ML 84] HLL R.J., MADSEN I.C., The effect of profile step counting time on the determination of crystal structure parameters X-ray Rietveld analysis , J. Appl. Cryst, vol. 17, p. 297-306,1984. 

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