The George Boole Foundation
The Decision Analysis Initiative





The design and construction of complex engineering products like an aircraft carrier or jet engine make use of decision analysis systems centred on a sequence of structured calculations. These help guide the design process and provide a transparent and documentated audit trail of all design decisions.



Decision analysis procedures can integrate information on known lead arial and costs associated with alternative component supply chains (including in-plant supply) enabling a reasonable determination of the cost and time implications of changes in design arising from customer requests, from suggestions from design engineers or changing circumstances. Simulation of the implications of design modifications can provide a very low cost means of assessing the relative risks associated with the introduction of different design changes, including changes in project lead arial, feasibility of meeting deadlines and assessing the cost implications before any final decision is taken to commit resources to a proposed change in design.
Structured calculations

Calculations are the most common operations used in decision-making in most product and process engineering design. Decision analysis systems centred on structured calculations involve the arrangement of a sequence of relevant coded formulae (algorithms) arranged in the order of the sequential logic of necessary design decisions. The formulae are based upon knowledge of known relationships between the key determinants of each stage of a design. For example the required strengths of structural beams in a civil engineering design will change according to the overall configuration of a building, its height, number of floors and known likely loads each type of beam will be required to support. In addition, depending upon the materials used in construction, architects can achieve different desired visual impacts without compromising safety.

In order to achieve an error-free design sequence which takes into account a large number of possible "materials options" the correct formulae need to be applied in order to achieve accurate calculations. Structured calculations are an array of formulae which can be accessed according to the specific aspect of a design being managed and expert systems support including decision trees (see Deduction) help guide the designer through the appropriate "design route". In such design processes the output of one calculation represents the input of the next one. Rather than create a single integrated formula the stepwise approach provided by structured calculations arrays permit intermediate checks to be made on such things as costs, specific component lead arial and other issues. In addition structured calculation processes permit an audit trail of design decisions in order to record the design process and to facilitate subsequent trouble-shooting of designs should the need arise or to introduce the redesign of specific product components with the minimum of adjustment.

Sequencing calculations

The sequences and types of algorithms (formulae) to be used are defined by the type of design process, be this a jet engine, an aircraft carrier or building. Each calculation covers a range of possible values whose limits are dependent upon a fund of knowledge concerning the cause and effect relationships within the domain in question. The correct sequence of relevant calculations follows a process of "component specification" and then "component integration" to build up the product design step by step. Such a system can be considered to be a highly sophisticated "professional calculator".

Applications

Most manufacturing and industrial sector design processes can be greatly assisted through dedicated online decision analysis systems so as to enable identified corporate staff have oversight of the critical design elements of relevance to their activities.












Construction design involves a structured sequence of calculations to accommodate several design requirements (decision criteria) to identify optimal combinations of appearance, safety, materials & costs.
This can ensure appropriate collaboration between key design staff providing transparency and a productive exchange on information on technical, economic, financial and legal aspects of designs. Onlien system also permit alternative proposals for design improvements to be simulated (see simulations) and costed without committing any resources.

How DAI can help

We will assist practitioners to develop appropriate online structured calculation packages as a central component for online decision analysis systems. This involves a review of current design practice and identifying those process components which can be transferred to an online operation. Essentially this is an automation of current practice. At a subsequent stage we can assist in providing guidance in the process of integration of other key decision analysis components which influence overall design outcomes.

By using easy-to-follow visual modelling techniques, cross-disciplinary transparency and understanding is maximised so as to gain acceptance on each decision analysis model construction stage and in accordance with the specific sequence of decision tasks to be automated.

Our systems engineering economists are are accustomed to assessing and encoding all relevant technical, economic, financial, regulatory and legal criteria into operational models.

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