Four Factors

We have already discussed the four factors which characterise NDT inspection. In Table 1 we summarise the influence of these factors on the use of each of the three main AI techniques. 

This experiment describes a fixed-size simplex optimization of a system involving four factors. The goal of the optimization is to maximize the absorbance of As by hydride generation atomic absorption spectroscopy using the concentration of HCl, the N2 flow rate, the mass of NaBH4, and reaction time as factors. 

The most widely used and best known resistance furnaces are iadirect-heat resistance furnaces or electric resistor furnaces. They are categorized by a combination of four factors batch or continuous protective atmosphere or air atmosphere method of heat transfer and operating temperature. The primary method of heat transfer ia an electric furnace is usually a function of the operating temperature range. The three methods of heat transfer are radiation, convection, and conduction. Radiation and convection apply to all of the furnaces described. Conductive heat transfer is limited to special types of furnaces. 

A key parameter in determining the possibiUty of a self-sustained chain reaction is the value of k for an infinite medium, k. In the four-factor formula,... 

Casting is used foi kiegulai external and internal shapes that are impractical, impossible, or too cosdy to produce using other methods. The choice of an aEoy for any casting usuaEy depends on four factors metal cost, castabEity, properties, and final cost. A cost analysis determines the most economical method of producing a casting, although frequently the choice can be based on experience. 

Theoretical Formulation of the Separative Efficiency. The separative efficiency E of a countercurrent gas centrifuge maybe considered to be the product of four factors, all but one of which can be evaluated on the basis of theoretical considerations. In this formulation the separative efficiency is defined by... 

Active attack is commonly caused by microorganisms. Four factors must be present for a diagnosis of microbiologically influenced corrosion ... 

The natural structural frequencies of most large systems are also in the low-frequency range, and care must be exercised to avoid resonant couplings between the structure and the foundation. The excitation in rotating machinery comes from rotating unbalanced masses. These unbalances result from four factors ... 

In considering either multiple payments or cash into and out of a company, the present values are additive. For example, at 6 percent interest, the present value of receiving both 1,000 in one year and 1,000 in three years would be 943.40 + 839.62 = 1,783.06. Similarly, if one were to receive 1,000 in one year, and pay 1,000 in 3 years the present value would be 943.40 - 839.62 = 103.78. It is common practice to compare investment options based on the present-value equation shown above. We may also apply one or all of the following four factors when comparing investment options Payback Period Internal Rale of Return Benefit-to-cost Ratio and Present Value of Net Benefit. But as we will see later, it is rate of return that is usually the most enlightening when considering an investment. 

It is eommon praetice to eompare investment options based on the present-value equation shown above. We may also apply one or all of the following four factors when comparing investment options Paybaek period Internal rate of return Benefit-to-cost ratio and Present value of net benefit. 

This is defined as the tendency to inhibit emotional responses during a crisis (Roger and Nesshoever, 1987). The scale which measures this concept has four factors, namely ... 

The cost of PV electricity is largely determined by four factors cost of the PV modules, the efficiency of converting sunlight to electricity, the balance-of-sys-tem costs, and the lifetime of the systems. There are many combinations of these factors that provide about the same cost of electricity. Modules are now available that are designed to last at least thirty years. 

This chart is useful, although it is often misused. Four factors must be understood before using the chart ... 

Considering the effects of the four factors described above, the amount of luciferin required to obtain highly reliable data would be... 

For the model formulated by the above postulates, the specific desorption rate rd, i.e. the molar rate of release of the adsorbed species under consideration from the unit surface, is in general given by the product of four factors ... 

Solution This problem illustrates the adjustment of Kthermo for temperature. Equation (7.35) expresses it as the product of four factors. The results in Examples 7.10 and 7.11 are used to evaluate these factors. 

Oral Isotretinoin (13-cis-retinoic acid) efficacy is based on its specific actions against all four factors implicated in acne pathogenesis. Isotretinoin targets are 1) sebum suppression ... 

Now that we have seen each of the four factors individually, we need to consider what order of importance to place them in. In other words, what should we look for first And what should we do if two factors are competing with each other ... 

There are, of course, other exceptions, but the one explained above is the most common. In most cases, you should be able to apply the four factors and provide a qualitative assessment of acidity. 

Now we can compare them and ask which negative charge is more stable, using our four factors ... 

Remember the four factors, and what order they come in ... 

Four factors are used to determine which reaction takes place. These four factors make perfect sense when we understand the mechanisms. So, it makes sense to start off with the mechanisms. 

We mentioned before that we need to consider four factors when choosing whether a reaction will go by an SnI or Sn2 mechanism. These four factors are electrophile, nucleophile, leaving group, and solvent. We will go through each factor one at a time, and we will see that the difference between the two mechanisms is the key to understanding each of these four factors. Before we move on, it is very important that you understand the two mechanisms. For practice, try to draw them in the space below without looking back to see them again. 

Now that we have seen all four factors individually, we need to see how to put them all together. When analyzing a reaction, we need to look at all four factors and make a determination of which mechanism, SnI or Sn2, is predominating. It may not be just one mechanism in every case. Sometimes both mechanisms occur and it is difficult to predict which one predominates. Nevertheless, it is a lot more common to see situations that are obviously leaning toward one mechanism over the other. For example, it is clear that a reaction will be Sn2 if we have a primary substrate with a strong nucleophile in a polar aprotic solvent. On the flipside, a reaction will clearly be SnI if we have a tertiary substrate with a weak nucleophile and an excellent leaving group. 

In Chapter 3, we learned how to analyze the four factors that stabilize a negative charge (ARIO). The I in ARIO stood for induction. We saw that neighboring halogens can withdraw electron density and stabilize the negative charge ... 

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