Simplicity, engineering design

The unit operations found in each area are discussed, covering control system design, instrument selection, and materials of construction. It is obvious that control systems engineers will have different opinions as to what controls, instruments, and materials are the best to be used for any application. The selections here emphasize simplicity of design and the use of quality equipment and materials of construction. This philosophy does not result in the lowest initial cost, but it has produced plants that are easy to start up and operate, with high onstream factors and long lives. 

Most modern manufacturing plants are complex pieces of engineering. In fact it seems that many chemical engineers judge the success of a design not by its simplicity but by its complexity. 

A kinetic model based on the Flory principle is referred to as the ideal model. Up to now this model by virtue of its simplicity, has been widely used to treat experimental data and to carry out engineering calculations when designing advanced polymer materials. However, strong experimental evidence for the violation of the Flory principle is currently available from the study of a number of processes of the synthesis and chemical modification of polymers. Possible reasons for such a violation may be connected with either chemical or physical factors. The first has been scrutinized both theoretically and experimentally, but this is not the case for the second among which are thermodynamic and diffusion factors. In this review we by no means pretend to cover all theoretical works in which these factors have been taken into account at the stage of formulating physicochemical models of the process... 

Because of its structural simplicity and instrumental role in protein function, the coiled coil is one of the most investigated protein folding motifs. Native coiled-coil sequences and their mutants have been synthesized and studied. Numerous model coiled-coil peptides have been designed de novo [22]. Although many theoretical questions remain unanswered, much has been learned about the sequence-structure relationship. It is even possible to design and engineer new coiled-coil sequences and structures that have never existed before [23]. 

Because of its simplicity, the straight-line method is widely used for determining depreciation costs. In general, design engineers report economic evaluations on the basis of straight-line depreciation unless there is some specific reason for using one of the other methods. 

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