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4. Methods, Theories, and Tools
Pages 20-43

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From page 20...
... An additional set of h-~31s address variability, quality, and uncertainty in the design process (Projected Latent Structure, the ~raguchi method, and Six Sigma)
From page 21...
... System and component trades must be made concurrently, which requires effective methyls for flow-down and tracking of requirements, as well as flow up and tracking of status. The tight schedules resulting from reduced cycle times require disciplined scheduling and monitoring of key decisions as well as management of the required sequencing and the downstream impact of design decisions.
From page 22...
... In the Pugh method a decision matrix is prepared with columns to identify design concepts Variant) and the rows to represent criteria.
From page 23...
... Quality Function Deployment is used to identity critical customer attributes and to create a specific link between customer attributes and denim parameters. Matrices are used to organize information to help marketers and design engineers ~ tsualize and answer three primary questions: · What attributes are critical to our canners?
From page 24...
... DECISION MATRIX TECHNIQUES Decision matrix techniques are used to define attributes, weight them, and appropriately sum the weighted attributes to give a relative ranking among designs. An example of the framework for such a process is shown in Figure 4-3.
From page 25...
... The "Weighted Sum of Attributes" decision remix shown in Figure 4-4 is an example typical of frequently encountered design decisions in which ~ Variety of concepts are viable but vary considerably in their ability to meet conflicting r~Luitements. In the example, for instance, all the concepts will provide attachment, but only one has lr;~;ose parts.
From page 26...
... The t'\\reighted Sum of Attributes" decision matrix is an important decision tool, but its limitations need to be~ well understood by the decision maker. ANALYTIC HIERARCHY PROCESS The Analytic Hierarchy Process (AMP)
From page 27...
... Unfortunately, it can be shown that the addition of a new alternative may change the ranking of existing alternatives, a property seen as undesirable in a decision process. The analytic hierarchy process luaus
From page 28...
... . The strategy in the design decision process for controllable design parameters is to use analysis, including statistical tools such as "Design of Experiments," to select values (settings; for these parameters such that the product performance is within acceptable limits.
From page 29...
... In chemometrics the X factors Controllable variables) may include the many spectroscopic measures taken on samples drawn from a chemical process, along with associated measures of temperatures, pressures, concentratio~i&' and flow rates.
From page 30...
... , in two recent proceedings of the biennial International Conference on Artificial Intelligence in Design, provide a broad view of the many efforts in this area, which include design processes (decision-driven process models, cognitive theories of design decision making) , knowledge management (representation, acquisition, sharing)
From page 31...
... This much more focused design support tool combines intelligent support with multi-stakeholder, multi-~ttr~bute market models and quality function deployment representations of relationships among product functions/features and stakeholders' attributes. The Product Planning Advisor has been employed in hundreds of product planning efforts, many involving top high-technology companies.
From page 32...
... FORMAL METHODS FOR REPRESENTING DESIGN PROBLEMS This section covers some limited formal meth<~UL$ and theories for representing design problems. They are selected as representatives from different schools of thought in approaching design problems: traditional engineering, decision theory and artificial intelligence.
From page 33...
... ; and continuo~slv variers n~rameterS in deign calculations or within algorithms representing a Different languages are used to represent engineering and design knowledge at different times, and the same knowledge is often cast in different Trudges in order to serve different purposes. For example, fundamental structural-mechanics knowledge can be expressed analytically, as in formulas for the vibration frequencies of structural columns, numerically, as in discrete minimum values of structural dimensions or in finite element meshing algorithms for calculating stresses and displacements; and in terms of heuristics or rules of thumb, as in the knowledge that the first-order earthquake response of a tall, slender building can be modeled as a cantilever beam whose foundation is excited.
From page 34...
... This could be why the best practical applications to date use axiomatic design in combination with other design methods. One can use the independence axiom in combination with robust Taguchi methods to examine which design parameters to use in achieving a robust design.
From page 35...
... fiche framework recognizes some key aspects of design, in the context of decision theory, that other methods fail to consider: (1) that all design decisions are made under conditions of significant uncertainty and risk; (2)
From page 36...
... Economists use techniques from constrained optimization, decision theory, game theory, and microeconomics (the stud off resource allocation) in general to solve such problems.
From page 37...
... (Ilhe case of a multi-product ilirm is more difficult to analyze, but the same principles can be applied.) Decision making in economics, whether for Hers or firms, is based on constrained optimization; however, the objective functions and constraints faced by consumers are different from those for firms.
From page 38...
... Some decision analysis and applied decision theories are also included in this comparison. Concurrent engineering is included here as a tool: bt~t it is more of an operating philosophy.
From page 39...
... " One could use Table 4-2 and the discussion in this chapter as a guide to choosing approaches for design application. For example, effective choices include: market; Concurrent engineering as an overall homework for decreasing costs and time to TRIZ for generating alternatives;
From page 40...
... A variety of tools, methods, and theories have been developed over time to help describe and facilitate decision making processes, and some of these have been applied to various aspects of design, but none approach a general and useful theory fundamental to all areas off design. In current practice each of these formal apprr:~e:hes to representing design processes is valuable yet individualistic.
From page 41...
... 1996. Artificial Intelligence in Design '96.
From page 42...
... 1987. The analytic hierarchy process—what it is and how it is used.
From page 43...
... 1981. General design theory and a (:-hD system.


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