Logic of Engineering Designing

1
Logic of Engineering Designing

• iga Turk

2
Contents

• Short introduction to modeling
• Reference models
• structure function behavior model
• Short introduction to logic
• Logic of the SFB model

3
Literature

• Books
• Eastman, C.M. (1999). Building Product Models,
  CRC press, ISBN 0-8493-0259-5.
• Sowa, J.F. (2000). Knowledge representation,
  Brooks/Cole, ISBN 0-534-94965-7.
• Sowa, J.F. (1984). Conceptual Structures
  Information Processing in Mind and Machine,
  Addison Wesley, ISBN
• Raphael, Smith Computer Aided Engineering.

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Definitions

• model
• reproduction of something m-w
• perfect deserving to be imitating
• modelling a process during which models are
  created
• modeller a person who is modelling
• examples
• model railroads, model buildings, finite elements
  models

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Evolution of modelling in construction

• construction is about big 3D objects
• communication is essential
• communication through drawings
• contributors
• Brunelleschi, 15th century, scaled drawings
• Monge, 18th century, projections
• exchange of drawings vital information
  technology!
• drawing is also a model

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Philosophical foundations of modelling

• how we understand the world around us
• the meaning triangle
• Aristotle
• things
• words
• experiences in the psyche
• Ogden and Richards
• object
• symbol
• concept

OBJECT
SYMBOL
CONCEPT
B-E-A-M
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Meaning triangleObject

• The object is any entity from some real or
  imagined world about which an idea is held. for
  example the beam in the Nada Ward Museum of
  Modern Art in Kobe damaged by an earthquake

OBJECT
SYMBOL
CONCEPT
B-E-A-M
8
Meaning triangleSymbol

• The symbol is an auditory, visual, or other form
  of utterance that is taken to stand for the
  object when communicated as part of a language

OBJECT
SYMBOL
CONCEPT
B-E-A-M
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Meaning triangleConcept

• The concept is the idea or thought of the object
  as held in the mind of a person, for example a
  structural concept of a beam. as illustrated.

OBJECT
SYMBOL
CONCEPT
B-E-A-M
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Mind and machine

• It has been suggested that intelligent systems
  achieve their intelligence by manipulating
  symbols of real world objects. Humans do it by
  manipulating "experiences in the psyche",
  concepts or "mind models". Computers could
  manipulate symbolic representations of the
  models. Therefore, computers could achieve
  intelligence, just as humans do, if only the
  models and the manipulation rules could be
  complex enough.humans are intelligent, because
  they and computers handle symbols.

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Mental models

• when we think, we create a model of the messy
  real world situation
• we manipulate the model
• we solve a problem
• models can be represented as semantic networks

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Semantic networks
wall

• nodes concepts
• arches relations between concepts
• example
• PS similar tohypertextnetworks!

has
has
door
window
is-an
is
is-an
opening
white
reduces
strength
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Moving semantic networks into a computer

• repetition, reuse, frames or similar
• computer program should be good at helping in
  several situations
• instances - unique
• 11 mapping to real world problem
• this wall in this room
• concepts - generic
• one generic concept corresponds to several real
  world items
• walls in general

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Reference models

• reference model
• impose certain perspective on the world to be
  modelled
• define how to model
• how to decompose the model
• GARM
• RATAS
• form, function, behaviour

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GARM

• General AEC Reference Model
• Describes a Product Definition Unit (PDU)
• PDU has characteristics that refer to aspect of
  the product. Aspects
• strength, cost, safety, durability...
• PDU has stage discriminator to include life
  cycle
• as required, designed, planned, built, used
  altered, demolished

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GARM Functional Units and Technical Solutions

• defined and required characteristics
• one functional unit, several technical solutions
• each technical solution, several functional units

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GARM FU/TS Example
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GARM Building example
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Form, function, behaviour (fit, working principle)

• popular with design sciences
• form the structure of the design as captured by
  the parts hierarchy.
• function the intended behaviour of the artifact
  that is designed as might be found in a
  functional classification of parts.
• behaviour the causal relationships between
  different parts of the artifact.
• fit how do the parts of the design fit together?
• working principle hydraulic, electro-mechanic
  etc.

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Form, function, behaviour model

• products or their parts have
• form or structure
• function ... the purpose they server
• behaviour ... how they react to environment
• for example a wall
• form x,y,z,w,d,h
• function load bearing,heat insulating, sound
  insulating
• behaviour what happens

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Inference

• deduction
• abduction
• induction

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Types of inference
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and inference

• cause environment
• structure structure (cause?)
• function effect
• behaviour effect
• working principle rule
• fit ???

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Formulation
formulation
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Formulation synthesis

Sas-designed
F
synthesis
formulation
Brequired
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Formulation, synthesis, analysis, evaluation

Sas-designed
F
synthesis
analysis
formulation
evaluation
Brequired
Bpredicted
27
construction

construction
Sas-designed
F
synthesis
analysis
formulation
evaluation
Brequired
Bpredicted
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measuring, monitoring

construction
Sas-designed
F
Sas-built
prediction
synthesis
analysis
formulation
monitoring
induction of new models
evaluation
Brequired
Bpredicted
Bmeasured
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Engineering tasks

• analysis deduction
• structure cause rules ? effect
• structure cause working principle ? function
• simulation deduction
• structure cause rules ? effect
• structure cause working principle ? behaviour
• diagnosis abduction
• structure effect rules ? cause
• structure behaviour working principle ? cause
• synthesis abduction
• effect rule ? structure
• function behaviour working principle ?
  structure
• interpretation induction
• cause effect rule
• cause structure behaviour working principle

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Tasks by Newell

• well defined
• closed worlds
• explicit goals
• described by algorithms
• ideal situation

• ill defined
• open world
• partially defined goals
• procedures to obtain solutions not known
• reality of engineering tasks