Selection from alternatives

Types and Accuracy of Estimates Capital-cost estimates may be required for a variety of reasons, among others to enable feasibility studies to be carried out, to enable a manufacturing company to select from alternative investments, to assist in selection from alternative designs, to provide information for planning the appropriation of capital, and to enable a contractor to bid on a new project. It is therefore essential to achieve the greatest accuracy of estimation with a minimum expenditure of time and money. 

CFSU Control of the functions of system units. Depending on the availability of needed information in the database about correlations between various processes, a version is selected from alternative versions that does not contradict the database. 

There are a number of predecessors for group decision support technology. Decision rooms, or situation rooms, where managers and boards meet to select from alternative plans or courses of action, are very common. The first computer-based decision support facility for group use is attributed to Douglas C. Engelbart, the inventor of the (computer) mouse, at Stanford in the 1960s. A discussion of this and other early support facilities is contained in Johansen (1988). 

A problem is the tendency of designers to be satisfiers rather than optimizers. That is, designers tend to stop as soon as they have one feasible solution. For example, when designing an assembly line, the designer may stop as soon as there is a solution. For an optimum solution, there must be a number of alternatives to select from. Alternatives tend to suggest further alternatives, so stopping too soon can limit solution quality and acceptance. 

The thermodynamics and physical properties of the mixture to be separated are examined. VLE nodes and saddles, LLE binodal curves, etc, are labeled. Critical features and compositions of interest are identified. A stream is selected from the source Hst. This stream is either identified as meeting all the composition objectives of a destination, or else as in need of further processing. Once an opportunistic or strategic operation is selected and incorporated into the flow sheet, any new sources or destinations are added to the respective Hsts. If a strategic separation for dealing with a particular critical feature has been implemented, then that critical feature is no longer of concern. Alternatively, additional critical features may arise through the addition of new components such as a MSA. The process is repeated until the source Hst is empty and all destination specifications have been satisfied. 

Isolation procedures for many biochemicals are based on chromatography. Practically any substance can be selected from a crude mixture and eluted at relatively high purity from a chromatographic column with the right combination of adsorbent, conditions, and eluant. For bench scale or for a small pilot plant, such chromatography has rendered alternate procedures such as electrophoresis nearly obsolete. Unfortunately, as size increases, dispersion in the column ruins resolution. To produce small amounts or up to tens of kilograms per year, chromatography is an excellent choice. When the scale-up problem is solved, these procedures should displace some of the conventional steps in the chemical process industries. 

Often an organization will strive for the elimination of a specific toxic material from a given process. Alternatives will also have other hazards and risks that require an informed choice. The industrial hygienist, chemist, and safety engineer play an important role in developing the information for making the selection between alternatives. 

Provide at least three, and perhaps four feed nozzles in addition to the one theoretically calculated to be the optimum location. Select these feed locations approximately two and four trays above and below the design basis or theoretical location. These extra nozzles must be oriented on the column so they have proper feed entry spargers or distributors (entry can be onto the tray or into the downcomer) and can be valved from a feed manifold to select the alternate desired location for testing purposes. 

The situation is quite different for the excess properties of one particular mixture A + B, where it is now — ( bb/ aa) 1 and p = (r B/r A) — 1 which are required (and not simply bb/ aa and Tbb/ aa) it is essential here to get values which are as accurate as possible for these quantities. We shall therefore deduce 8 and p (or alternatively bb/ aa and bbAaa) from different source data, see how far these values agree with each other, and finally select from them an average value. The following experimental data were used ... 

Acid gas removal is the removal of sulfur compounds and CO2 (acid gas) from process gas streams. The following sections describe available process alternatives, design options, and guidelines for selection among alternatives. 

The report (5) on the study recommended that a less active charcoal be tested. A literature survey did not yield any conclusive evidence for successful collection by recovery from alternative sorbents. On the basis of the little information available, we selected petroleum charcoal and three porous polymers to test (petroleum charcoal is less active than coconut charcoal). All the porous polymers were based on aromatic monomers, and they should be good collectors for nonpolar aromatics. Aliquots of 113 pg diphenyl were spiked onto these sorbents, and the samples were desorbed with various solvents. The results are given below. 

Informed substitution enables the move from the use of chemicals of concern to safer chemicals, while minimizing the likelihood of unintended consequences. This technique has been demonstrated to be an effective tool and is recognized [8] for guiding the evaluation of chemicals or products in the context of functional need. The options for meeting a functional need can be arrayed along a spectrum of preference based on environmental and human health characteristics. Decisions based on informed substitution will avoid an inclination to select an alternative that may appear more benign only because it is poorly characterized. 

An alternative route starting from serine 73 or threonine 68 74 makes use of diethoxy-triphenylphosphorane. Attempts to asymmetrically synthesize (25)-aziridine-2-carboxylic acid (1) by treating a, 3-dibromopropanoates with chiral amines 75 or by the Staudinger reaction from oxirane-2-carboxylic acid ester 70,76 leads to optically impure products, whereas 3-alkyl derivatives of tert-butyl aziridine-2-carboxylates can be prepared with high cis-selectivity from a-halo ester enolates and jV-trimethylsilyl imines. 77 Moreover, when optically... 

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