Margining

Thus an excess of ammonia in the reactor has a marginal eflFect on the primary reaction but significantly decreases the rate of the secondary reactions. Using excess ammonia also can be thought of as operating the reactor with a low conversion with respect to ammonia. 

These marginal costing approaches to costing steam are unsatisfactory. Within operating companies, few subjects generate more controversy than the value placed on different steam levels. 

In preliminary process design it mig] it be necessary to use marginal costs for steam, but the designer should keep in mind the dangers of using such costs. 

In practice, the user prefers the densest possible motor fuel that is compatible with the specifications, for it gives him the best volume NHV and highest fuel economy. It is estimated that an increase in density of 4 to 5% brings a reduction in consumption of 3 to 5%. Finally for the refiner, a margin of 50 thousandths accorded for the density of each type of gasoline, makes an acceptable compromise, while a tightening of the specification would be too constraining. 

The flroduction of No. 1 fuel oil is thus quite marginal whereas the BTS and TBTS products will be undergoing important development in the coming years. In applications as diesel fuel, ordinary No. 2 fuel, and No. 2 BTS fuel are the most commonly used. 

There are few coking units in the world, and the majority of them is found in the United States, such that coke production is marginal. Different coking processes have been described, but only two have survived (see Chapter 10) ... 

To lessen the risk of pumping sludges or slurries into a unit, the practice is to leave a safety margin of 50 cm (heel) below the outlet nozzle or install a strainer on the pump suction line. The deposits accumulate with time and the tanks are periodically emptied and cleaned. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

A comfortable margin is maintained between the flowing tubing head pressure (downstream of compression) and the minimum pressure required for export, since the penalties for not meeting contract quantities can be severe. The decision not to install a fourth stage of compression in the above example is dictated by economics. During the final part of the pressure decline above, the field production is of course also declining. 

Various types of subsea production systems are being used and their versatility and practicality is being demonstrated in both major and marginal fields throughout the world. 

The evolution of the defects is only acceptable if the materials are sufficiently ductile. Prior study of the acoustic emission of the materials used should show that detection of defects and their evolution take place at pressures with a sufficiently wide margin relative to the burst pressure. 

The defect was detected and located during the proof test, and acoustic emission could follow its evolution until 20 bars during the burst test. After the pressure, the evolution of defect stopped till the burst. This test confirm the capability of acoustic emission to detect the evolution of defect during a pneumatic test with a sufficiently wide margin relative to the burst pressure. 

In order to perform this procedure on all elements of matrix A a margin with constant values aj and a ,j and a length of X (left/right) or % (top/bottom) is added on each side of matrix A. The two new matrices A and Ai are combined to form a resulting matrix Ax for the filtering in x-direction ... 

As to inspections performed on light-alloy castings, the expert group agrees on the specifications of marginal conditions that should be met with regard to the required IQI detectability. 

The rupture process of a soap film is of some interest. In the case of a film spanning a frame, as in Fig. XIV-15, it is known that rupture tends to originate at the margin, as shown in the classic studies of Mysels [207, 211]. Rupture away from a border may occur spontaneously but is usually studied by using a spark [212] as a trigger (a-radia-tion will also initiate rupture [213]). An aureole or ridge of accumulated material may be seen on the rim of the growing hole [212, 214] (see also Refs. 215, 216). Theoretical analysis has been in the form of nucleation [217, 218] or thin-film instability [219]. 

We must now mention, that traditionally it is the custom, especially in chemo-metrics, for outliers to have a different definition, and even a different interpretation. Suppose that we have a fc-dimensional characteristic vector, i.e., k different molecular descriptors are used. If we imagine a fe-dimensional hyperspace, then the dataset objects will find different places. Some of them will tend to group together, while others will be allocated to more remote regions. One can by convention define a margin beyond which there starts the realm of strong outliers. "Moderate outliers stay near this margin. 

Model optimization is a further refinement of the secondary and tertiary structure. At a minimum, a molecular mechanics energy minimization is done. Often, molecular dynamics or simulated annealing are used. These are frequently chosen to search the region of conformational space relatively close to the starting structure. For marginal cases, this step is very important and larger simulations should be run. 

Margin notes direct students to colorplates located toward the middle of the book... 

Bold-faced Key Terms with Margin Definitions... 

---