Step counting methods

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

The technique is based on the premise that the capital cost is determined by a number of significant processing steps in the overall process. Factors are usually included to allow for the capacity, and complexity of the process material of construction, yield, operating pressure and temperature. 

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). 

Bridgwater, IChemE (1988), gives a developed relatively simple correlation for plants that are predominantly liquid and/or solid phase handing processes. 

Q = plant capacity, tonne per year s = reactor conversion 

IChemE (1988) gives a simple equation for gas phase processes updated to 1998  

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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. 

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. 

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... 

Figure 4.66 Reduced synthesis tree for synthesis of vincristine by Fukuyama method. Step counts are shown in parantheses.

Spectrex ILI-1000 Particle Counter combines the Prototron with a Particle Profile Attachment (multichannel analyzer). The instrument has been used [118] for examining volcanic ash. AC Fine Dust was used for calibration in eight 5 pm steps, which indicated that accurate data was obtained for sizes above 2 pm. It has also been shown to correlate well with the more tedious filtration and counting method for large volume parenteral liquids [119]. Although semi-transparent containers or liquids reduce the amount of transmitted light flux, the instrument gives valid data for particulates in oil [120]. 

Using the mass you calculated in step 2 and a balance, measure out another 200 small beads. Record the amount of time it takes you to count small beads when using this counting method. 

The direct count methods are dependent on the ability of the investigator to recover bacteria from the sample, to observe stained particles, and to identify such particles as bacteria. Each one of these steps could limit the accuracy of the method, depending on the circumstances. 

In the past 40 years, many attempts had been done to evaluate the ambulatory function and condition of humans. This kind of evaluation is considered as useful indicators of a person s condition. Most of the methods being developed are for the evaluation of the ambulatory function and condition of normal and healthy subject or certain patients like those who surfer coronary artery disease, multiple sclerosis, musculoskeletal disorders and etc. Their main focus is to find out about the static and dynamic activities, postural control, swaying motion, step counting, energy expenditure, fall risk of the elderly and etc. Yet, very little effort had been put in the research regarding the amputees ambulation with their prosthesis. 

An improvement of this method—the so-called biased sampling [55] (or inversely restrieted sampling)—suggests to look ahead at least one step in order to overcome the attrition. Consider a SAW of i steps on a -coordination number lattice. To add the / + 1st step one first checks which of the = q — neighboring sites are empty. If k qQ > k>0) sites are empty one takes one of these with equal probability 1 /A if A = 0 the walk is terminated and one starts from the beginning. This reduces the attrition dramatically. Now each A-step walk has a probability PAr( i ) = Ylf=i so that dense configurations are clearly more probable. To compensate for this bias, each chain does not count as 1 in the sample but with a weight... 

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