1. 1.3 Classifying Engineering Tasks
Knowledge Component 1: Theoretical Foundations
Computer-Aided Engineering
1.3 Classifying Engineering Tasks
2nd Edition
Ian F. C. Smith
EPFL, Switzerland

2. Module Information Intended audience Key words Author All
Engineering tasks
Inference
Well-defined tasks
Author
Ian Smith, EPFL, Switzerland

3. What there is to learn
At the end of this module, there will be answers to the following questions (see also the review quizzes):
What is the point of studying the links between logic and engineering tasks?
Should a computer provide single answers or choices?
What is the logical similarity between design and diagnosis?

4. Outline Engineering Tasks Inference Model of Information and Tasks
Well-defined and Poorly-defined tasks
(Newell 1960)

5. Definitions Structure (or Form)
Information represented in drawings (dimensions, location, topography, etc.) as well as properties of materials and environmental context. The scope of this definition is not limited to structural engineering!
Behavior
Includes parameters that describe how the structure reacts (deformations, stresses, buckling, creep, etc.)
Cause
External actions resulting in a change of behavior
Effect
Observed behavior under the influence of the cause

6. Engineering Tasks - Examples
Analysis
Structure Behavior
Simulation
Cause + Structure Effect
Diagnosis
Effect + Structure Cause
Synthesis
Required behavior Structure
= inference 6

7. Engineering Tasks (cont’d.)
Experimental Research or
Interpretation of Information
Structure
Behavior models
Behavior
Observe that synthesis is reverse analysis and diagnosis is reverse simulation

8. Outline Engineering Tasks Inference Model of Information and Tasks
Well-defined and Poorly-defined tasks

9. Inference
Inference is the reasoning involved in drawing a conclusion or making a logical judgment on the basis of evidence.
Rule: If cause then effect
Given cause, effect and rule, there are three types of inference
Deduction
Abduction
Induction

10. Types of Inference Type of Inference Given information
Inferred information
Deduction
Cause and rule
Effect
Abduction
Effect and rule
Cause
Induction
Cause and effect
Rule

11. Review Quiz I
What types of inference are more likely to have multiple answers?
What types of inference are more sensitive to missing information?
What types of inference can be associated with the five engineering tasks discussed earlier?

12. Answers to Review Quiz I
What types of inference are more likely to have multiple answers?
Abduction and induction. Their use is reliable only if it assumed that all possible rules are known
What types of inference are most sensitive to missing information?
Abduction and induction, since additional information may change answers
What types of inference can be associated with the five engineering tasks discussed earlier?
Analysis and simulation are deduction
Synthesis and diagnosis are abduction
Experimental research and interpretation of data are induction

13. Model of Information and Tasks
Outline
Engineering Tasks
Inference
Model of Information and Tasks
Well-defined and Poorly-defined tasks

14. Types of Information Three Categories Structure (S)
(dimensions, shapes, properties of materials, loads, temperature, etc.)
Behavior (B)
(deformations, shrinkage, creep, stress, displacements, corrosion, etc.)
Function (F)
(design criteria, specifications, desires of society, purpose, etc.)

15. Types of Information (cont’d.)
It is important to organize project information appropriately.
Good organization helps make modifications and additions without introducing update errors.
Modifications and additions always occur in large engineering projects.

16. Tasks and Types F = Function transformation B = Behavior S = Structure
Sas-designed
Brequired
synthesis
formulation
(standards)
F = Function
B = Behavior
S = Structure
transformation

17. Tasks and Types (cont’d.)F
Sas-designed
Bpredicted
Brequired
analysis
traditional evaluation
synthesis
formulation
(standards)
F = Function
B = Behavior
S = Structure
transformation
comparison

18. Tasks and Types (cont’d.)F
Sas-designed
Bpredicted
Brequired
analysis
traditional evaluation
synthesis
Sas-built
construction
formulation
(standards)
F = Function
B = Behavior
S = Structure
transformation
comparison

19. Tasks and Types (cont’d.)
monitoring F
Sas-designed
Bpredicted
Bmeasured
Brequired
analysis
traditional
evaluation
synthesis
Sas-built
construction
formulation
(standards)
prediction
improvement
of models
diagnosis
F = Function
B = Behavior
S = Structure
transformation
comparison

20. Tasks and Types (cont’d.)
The diagram in the previous slide is a representation of transformations. The iterative aspect is not shown. For example, if the traditional evaluation task fails, modifications to either F, Brequired or Sas-designed are carried out until traditional evaluation succeeds.
Analysis refers only to calculation. Improvements in analysis may also help the traditional evaluation task.
Creation of numerical models is a synthesis task
(creation of a model of Sas-designed).

21. Tasks and Types (cont’d.)
Some tasks are used to complement information.
For example, synthesis is used to add information concerning the structure.
It starts with assumptions about the environment in which the structure will be found.
Some tasks, such as synthesis and diagnosis, may have more than one possible solution.

22. Review Quiz II
What inference occurs at each task in the FBS schema ?

23. Answers to Review Quiz II
What inference occurs at each task in the FBS schema ?
deduction and abduction F
Sas-designed
Sas-built
deduction
abduction
abduction
deduction
deduction
abduction
Bpredicted
Bmeasured
Brequired
deduction
induction

24. Well-defined and Poorly-defined tasks
Outline
Engineering Tasks
Inference
Model of Information and Tasks
Well-defined and Poorly-defined tasks
(Newell 1960)

25. Well-defined Tasks
Carried out in closed worlds (all information is known)
and
Defined by goals explicitly expressed non-ambiguously by an objective function (for example, using a mathematical formula)
Described by algorithms that lead to identification and numerical quantification of a solution

26. Poorly-defined Tasks
Open world conditions prevail (not all information is known) or
Goals are defined only partially
Definitions of solutions are incomplete
Procedures for obtaining solutions are not known completely
Engineers are entrusted by society to perform poorly defined tasks. These tasks usually add the most value to society.

27. Questions
What is the point of studying the links between logic and engineering tasks?
Software requirements are similar for tasks that are associated with similar types of inference.
Should a computer provide single answers or choices?
It depends. Single answers are usually enough for deductive tasks whereas abductive tasks often require choices amongst many possibilities.
What is the logical similarity between design and diagnosis?
These tasks are both abductive. Therefore they require similar types of computer support.

28. Further Reading
Gero, J. S., Design Prototypes: A Knowledge Representation Schema for Design. AI Magazine, 11, 4 pp 26–48
Raphael, B. and Smith, I.F.C. Fundamentals of Computer-Aided Engineering, Wiley, 2003