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APPENDIX C WO RD U SAGE Analysis A discrete answer derived from a set of equations. The validity of the answer depends critically on whether the equations properly represent phenomena of concern and their conditioning. Computers are helpful tools for making complex calculations; however, if the results are not validated (usually by experiments), they may be erroneous due to discretization or numerical process problems, which cannot be anticipated. Decision A choice made by the design engineer regarding a particular solution for the problem at hand. Decision theory A conceptual, complete view of decision making that can apply to virtually any decision. Design (noun) The process by which human intellect, creativity, and passion are translated into useful artifacts. The plans or specifications for a product or service in the form of drawings, layouts, detail specifications, patterns, _ outlines, and processes that provide details of shape, materials, structure, layout, process steps, and configuration. Design (verb) To methodically apply science and engineering principles so as to convert ideas into useful products. The stages of design range from developing requirements. through svnthesizin~. analvzin~. and testing. to defining 1 7 "7 ~ 4,,7.' ., ~ ~ ~ ~ ~ and creating a final product design definition in the form of drawings, for instance. Design ability Mastery of scientific, engineering, and mathematical fundamentals, including analysis and experimental techniques in the presence of uncertainty. This encompasses such skills as conceiving, inventing, planning, and integrating, as they are applied to useful products in real environments. Design engineer (1) A person trained or professionally engaged in the application of science, mathematics, and design methods to create useful and economical products and services. Design engineer (2) A nerson or team responsible for assuring the functionality of devices or systems (i.e., that the performance and operations meet desired objectives reliably and efficiently); the people who do the "how" part of design. Designer Anyone who intentionally influences the function or form of an evolving artifact, including, especially in complex system, managers, specialists, and others. Engineering design Application of lore, empiricisms, intuition, and technical knowledge bases together with the use of scientific methods to the creation of useful and economical products. s
54 g APPROA CHES TO IMPRO BE ENGINEERING DESIGN Frame The relevant environmental elements and factors that may influence a decision, judgment, or conclusion. Key characteristics The small number of factors and tolerances considered crucial to the performance or assembly of a product. Knowledge bases The accumulated intuition, past experience, empirical data, and/or data extrapolations on which engineering designs are primarily based. Almost all industrial processes were developed by these means. In general, traditional knowledge bases are inadequate, given the additional societal, political, environmental, economic, and resource constraints confronting today's designers. Model A structure or equations containing all the appropriate physics, chemistry, and system characteristics. Physical A numerical constrained optimization technique for engineering design programming that emphasizes the physical attributes of the product and the physical constraints applied. Risk The possibility of loss or a bad outcome; the degree of probability of such an outcome. Risk assessment Estimate of the probability of a bad outcome. Risk evaluation Establishing the importance of the risk. Risk management Decision making to balance risk and risk mitigation. Robustness The ability to provide required performance independent of the variability encountered in manufacturing and use. Uncertainty An estimate of the amount by which a calculated value may differ from the true value. This is the result of the limited knowledge about a phenomenon, and is described by the designer or design team assigning a probability or probability distribution based on their level of knowledge. Validation of a result The proving of some result conclusively according to principles of logic and usually with the use of mathematics. This requires that the result and any associated assumptions or definitions be stated precisely. Validation of a model Testing the reasonableness of a model empirically by statistical hypothesis testing for lack of fit, ability to forecast, and parsimony or the attempt to judge whether the model coincides qualitatively and quantitatively with reality based on one or more case studies. o