Factored estimates

A 2 factorial design with two factors requires four runs, or sets of experimental conditions, for which the uncoded levels, coded levels, and responses are shown in Table 14.4. The terms Po> Po> Pfc> and Pafc in equation 14.4 account for, respectively, the mean effect (which is the average response), first-order effects due to factors A and B, and the interaction between the two factors. Estimates for these parameters are given by the following equations... 

The accuracy of a fixed capital estimate tends to be a function of the design effort involved. As the project definition is refined, the estimates evolve from the various preliminary phases, ie, order of magnitude, predesign, factor estimates, etc, into the more detailed estimates used for budget authorization, project control, and contracts. At the same time, the uncertainty in the estimate decreases from 50% to as Htfle as 5%. 

Study estimate (factored estimate). Better than order-of-magnitude requires knowledge of major items of equipment used for feasibihty surveys probable error up to 30 percent. 

Factor Estimations Most factor methods for estimating the total installed cost of a process plant are based on a combination of materials, labor, and overhead cost components. These can be conveniently grouped as... 

An alternative to a factored estimate, in some cases, can be a scaled estimate if the battery limits cost of a similar plant is known, but the size is different. The cost of the new plant, C , is equal to the known plant cost, C, times the ratio of the two plants capacity raised to a fractional power. That is ... 

Regardless of the estimating method, a process contingency should be added to the total plant cost for feasibility studies. As discussed earlier, this contingency depends on the status of the project. For most factored estimates, on a first of a kind process that is fairly well defined, the process contingency should be 30%. 

Organotin End-point Uncertainty factor Estimated PNEC (ug/i)... 

For the factored estimate a list is made of all pieces of equipment, and the delivered cost of each item is obtained. This could be determined by inquiring from manufacturers, from past records, or from published data. The delivered cost of all the equipment is summed and multiplied by an appropriate factor. According to Lang this factor would be 3.10 for a solids process plant, 3.63 for a solid-fluid plant, and 4.74 for a fluid plant. These factors are referred to as Lang factors. This estimate is often used in the preliminary stages of engineering, but is not extremely accurate. 

The factored estimate has one obvious drawback. It is very easy in the early phases of a process engineering study to forget some items. Since this will always... 

Similar arguments can be made for high-pressure and low-temperature apparatus. It can also be shown the Lang factor is dependent on the size of the equipment. As the size increases the proportionate cost of all other items decreases, and therefore the Lang factor should be smaller. The net result of the above inaccuracies is that the factored estimate as previously discussed cannot be very accurate. In 1951 W. T. Nichols estimated that the error could easily be as great as 60% of the cost of the plant. 

Source Miller, C.A. Factor Estimating Refined for Appropriation of Funds, American Association of Cost Engineers Bulletin, Sept. 1965, p. 92. 

Table 4.6 gives a few representative values for Kow and Kp for non-polar organic substances on typical soil material and Table 4.7 gives estimates on typical retardation factors estimated for an aquifer. The data show that many non-polar organic substances, with the possible exception of very lipophilic substances such as hexachlorobenzene, are not markedly retarded in aquifers that contain little organic material (foe = 0.001 - 0.005). On the other hand, such substances are effectively retained in soils rich in organic carbon. 

In the spirit of Eq. 3.39 and neglecting the ongoing decay of Schain(Q>0 due to local reptation, from the heights of the achieved plateaus we may obtain a first estimate for the amount of confinement. Identifying the plateau levels with a Debye-Waller factor describing the confinement we get d=44 A, a value that is a lower estimate for the true tube diameter since S ° (Q,t) is not fully relaxed. The horizontal bars in Fig. 3.16 are the predictions from this Debye-Waller factor estimate. 

Fig. 3.16 Scaling presentation of the dynamic structure factor from a M =36,000 PE melt at 509 K as a function of the Rouse scaling variable. The solid lines are a fit with the reptation model (Eq. 3.39). The Q-values are from above Q=0.05,0.077,0.115,0.145 A The horizontal dashed lines display the prediction of the Debye-Waller factor estimate for the confinement size (see text)...

In the classical statistical literature, one of the two qualitative factors is referred to as the treatments and the other qualitative factor is referred to as the blocks . Hence, the term block designs . In some studies, one of the qualitative factors might be correlated with time, or might even be the factor time itself by carrying out the complete set of experiments in groups (or blocks ) based on this factor, estimated time effects can be removed and the treatment effects can be revealed... 

Increasing attention is being given to developing methods to predict failure rate data for process equipment and systems. Such methods are beginning to appear in published literature. These methods include correlations, factored estimation procedures, and analogies to predict equipment failure rates. They are desirable because they offer efficient means of providing equipment failure rate data for risk assessments, and they can be conveniently incorporated into computer software. 

Kramer, H.J., W.A. van den Ham, W. Slob, and M.N. Pieters. 1996. Conversion factors estimating indicative chronic no-observed-adverse-effect levels from short-term toxicity data. Regul. Toxicol. Pharmacol. 23 249-255. 

Study estimate (factored estimate). This type requires knowledge of preliminary material and energy balances as well as major equipment items. It has a probable accuracy of-25 to -1-30 percent. 

Many companies have developed their own factored estimates using computer spreadsheets based upon their in-house experience and cost database information that they have built from company project history. For detailed estimates, the job is outsourced to design-construction companies that have the staff to perform those estimates. 

Table 1 Infiltration factors estimated as regression slope for the relationships between indoor and outdoor 24-h average concentrations of different particle metrics from RUPIOH study [13]...

Factored Estimates for Western Coal Commercial Concepts, C.F. Braun and Company, Project 4568-NW, ERDA-AGA (1976). 

MSC-E, 2002. EMEP workshop on Emission and Emission Factor Estimates, MSC-E Note... 

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