Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.10 $; site uiucme Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!uiucme!keith From: keith@uiucme.UUCP Newsgroups: net.cog-eng Subject: Knowledge and Design Message-ID: <11800003@uiucme> Date: Tue, 21-Jan-86 12:44:00 EST Article-I.D.: uiucme.11800003 Posted: Tue Jan 21 12:44:00 1986 Date-Received: Thu, 23-Jan-86 21:50:11 EST Lines: 66 Nf-ID: #N:uiucme:11800003:000:3020 Nf-From: uiucme.UUCP!keith Jan 21 11:44:00 1986 The fallacy of specialism and the chaos in design knowledge Third of a series The most important lesson I have learned from the structured analysis and programming crowd is the importance of the interactions between functional units of a design. In fact, the "data flow diagram" approach concentrates on those interactions; the functional parts themselves are almost incidental. In mechanical design we blithely ignore interactions unless they really are obvious. Material is selected for a heat exchanger for its creep and corrosions resistance - and only after they've purchased and bent millions of Pounds worth of tube into platens do they discover the material cannot be welded properly to put in small support pieces. A large pressure vessel is designed from a high-strength material which has terrible fracture resistance - and fails during testing at half the design pressure. The cost of correcting an error is a function of the time between the error and the correction. The "best" errors, the ones that cost a lot of money and company prestige, are made very early in the design. They are then discovered during manufacturing, when material order times and budgets have been used up. These can be incredibly expensive to correct, costing not only money, jobs and sometimes companies are lost in the process. Researchers, in order to "advance knowledge", are becoming more and more specialized. Greater detail and depth is required to be able to make a substantial change in what is known. As specialists dig their own holes deeper into the knowledge base, they lose sight of the other disciplines, who are digging adjacent holes. They ignore the interactions between the disciplines. The only problem is that tomorrow's engineers, today's students, are being taught mostly by researchers at universities. The interactions between disciplines are critically important in design, especially in the early stages. Most really expensive design failures are due to overlooked interactions (this, I think, can be documented from case studies). Most innovation in design comes from looking at these interactions in a new way - or noticing one that has traditionally been ignored (this is not so easy to prove, but to me at least it makes intuitive sense). We rely heavily on the interactions between components to insure the design serves its function. We rely on the interactions between subject areas in engineering for innovative ideas in design. But we rely on specialists, who for the most part ignore these interactions, to teach those who will design tomorrow. Small wonder almost every engineering firm has a 107-year-old consultant to advise them on their design problems. keith U of Illinois Mech Eng { stuff I don't know } uiucdcs!uiucme!keith Next instalment: A brief pause for philosophy p.s.: I have been delinquent in posting this instalment because Software Improvements have kept me off the net. p.p.s.: Sorry if this repeats an instalment, I have lost track.