Design process historical perspective

Lever (1987) presents an excellent overview of the regulatory process involved in FDA oversight of drug development, and gives the historical perspective for the evolution of the conservative process that is designed to ensure that any new pharmaceutical is both safe and efficacious. 

The best source of design information on fouhng is to find someone who has had to deal with a similar situation in the past and can give a historical perspective on what happened and how it was dealt with. The literature, especially the book by Bott [66], can be a source of case studies and contacts, and this information is fairly freely shared in the profession. The specialty water treatment chemical suppliers have large files of recorded experience in that area, and there is increasing use of chemicals in controlhng fouling in process streams as well. 

The aim of this book is to provide a practical engineeting description of techniques and processes in widespread use and, where feasible, provide sufficiem design and operating data to permit evaluation of the processes for specific aj lications. Limited data on processes that were once, but are no longer coimnercially important, are also presented to provide an historical perspective. Sutgect matter is generally limited to the removal from gas streams of gas-phase impurities that are present in relatively minor proportions. The removal of discrete solid or liquid particles is not discussed, nor are processes that would more appropriately be classified as separation rather than purification. 

Current practices in industrial pharmacy can now be put in perspective. Typically, the method of choice is univariate one variable at a time (OVAT). One variable is examined for a few conditions, which, in practice, are selected within a safe subset of the permissible design space. A value of this parameter is selected and kept subsequently constant. Another variable is then examined, a value is chosen, and the process continues sequentially. Intuitively, unless the target function is essentially a plane, if the end result is anywhere near the global optimum, it is only by chance. A historical reason for this dated practice is that the regulatory framework greatly discouraged implementation of the virtuous cycle mentioned above, which... 

This section will be presented in a historical fashion from oldest to newest technology. This will demonstrate the effect of technology on the design and implementation of DSP systems and offer a perspective on the effect of underlying technology on architecture of audio signal processing systems. 

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