Shortcut methods experience

The first step is to assume a set of temperatures Tj and vapor flows Vj. The temperatures can be obtained by linear interpolation between the condenser and reboiler temperatures, determined by dew point and bubble point calculations of products estimated by shortcut methods or on the basis of past experience with similar columns. The vapor rates are estimated from the specified distillate and reflux rates. Constant vapor rates are assumed above and below the feed. The... 

A heuristic is a statement concerning equipment sizes, operating conditions, and equipment performance that reduces the need for calculations. A shortcut method replaces the need for extensive calculations in order to evaluate equipment sizes, operating conditions, and equipment performance. These are referred to as back-of-the-envelope calculations. In this text, we refer to both of these experience-based tools as guidelines or heuristics. 

In this appendix, shortcut design methods will be defined to include rules of thumb and safety or experience factors. The following discussions catalog shortcut design methods according to their origin. This breakdown is useful in developing the perspective of the field. 

Often in the field, designs must be done quickly, for example, during an unexpected plant shutdown. For such cases, shortcut design methods are invaluable. The field invariably has the best perspective on how designs will perform for startup, shutdown, upset, or offload conditions. Experience factors come into play for field review of these design aspects. 

Demirplak and Rice developed the counter-diabatic control protocol while studying control methods that efficiently transfer population between a selected initial state and a selected target state of an isolated molecule [11-13]. The protocol has been studied for manipulation of atomic and molecular states [11, 12, 19] and spin chain systems [20, 21]. Experiments with the counter-diabatic protocol have been demonstrated for the control of BECs [22] and the electron spin of a single nitrogen-vacancy center in diamond [23]. The counter-diabatic field (CDF) protocol is identical with the transitionless driving protocol, independently proposed by Berry a few years later [24]. A discussion of the relationship between these approaches and several of the other proposed shortcuts to adiabaticity can be found in the review by Torrontegui and coworkers [10]. 

So what is to become of computational quantum chemistry under this new, unpleasant epistemology The finite store of computer power is compelling in the interest of speed, we must make assumptions, some of which will be unphysical (that is, unsupported by the Schrodinger equation). Some of these postulates, such as the apparent trivialities listed above, are largely upheld by experimental evidence. Other theories are more questionable, but the experiments that could incontrovertibly verify or refute them are not easily undertaken. In the end, many of the computational shortcuts taken today are known to be untrue, but it is hoped—not shown, albeit inductively supported—that the magnitude of the error will be within an acceptable margin. This final case is aesthetically distasteful but sometimes necessary (and, at times, surprisingly accurate). This chapter aims to demonstrate how each of these methods can be jointly and separately used to practically answer chemical questions in medicinal chemistry. 

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