The Engineering Method

EGR 3380

Engineering Design I

Based on “Discussion of the Method” by Billy Vaughn Koen

What is an Engineer?

• An Engineer is not defined by her product– Nano-robots– Airplanes– Embedded Computers

• An engineer is defined by her method– Finding the best change– Using available resources– In an environment of uncertainty

“To Engineer”

• The clergy in Iran engineered the firing of the president.

• The chessmaster engineered a perfect countermove.

• The general engineered a coup d'état without the loss of life.

Why is Engineering Such a Mystery?

• The Scientific Method– Well-understood, even by the layperson.– “Science is theory corrected by experiment.”– All variables held constant except one.– “Answer in the back of the book.”

• Extensively analyzed by philosophers

• None of these are true for the Engineering Method– Although engineers often employ science

and scientific reasoning

Four Key Elements of Engineering Problems:

• Change: the situation requires a change.

• Best: the best change is desired...

• Resources: using the available resources.

• Uncertainty: knowledge about the situation is incomplete and sometimes inconsistent

Four Key Elements of Engineering Problems:

• Change: the situation requires a change.

• Best: the best change is desired...

• Resources: using the available resources.

• Uncertainty: knowledge about the situation is incomplete and sometimes inconsistent

Change

time

Mea

sure

of C

hang

e

A

B

Change

• Four practical difficulties in getting from A to B:– Engineer lacks complete knowledge of the

world at A– The exact final state, B, is unknown and

cannot be anticipated– There is no single path from A to B– Engineering goals can change during the

process (the location of B floats!)

Change

• Is all change caused by engineers good?

– What about unintended consequences?• Aswan High Dam in Egypt• Can you name any others?

– Can you think of any engineering disasters?• Tacoma Narrows Bridge, WindBelt• Kansas City Hyatt Regency• Chernobyl Nuclear Power Plant in U.S.S.R.

The Final State (B) Cannot Be Fully Known!

Unforeseen Consequences

• Increased salinity of the Nile by 10%– Led to collapse of sardine industry

• Caused Coastal Erosion

• Displaced 100,000 Nubians– Drastically altering their way of life

• BUT provides ½ of Egypt’s electrical needs

Four Key Elements of Engineering Problems:

• Change: the situation requires a change.

• Best: the best change is desired...

• Resources: using the available resources.

• Uncertainty: knowledge about the situation is incomplete and sometimes inconsistent

Best

• Best for whom?– Westerners are conditioned to accept Plato’s

notion of the Ideal– A new concept of “best”

• Optimization theory– The Optimum compromise– Apollo Program

• Leapfrog learning• Political vs. Economic tradeoffs

Television Example: Best

Consider a television with only one knob:Increased knob setting results in sharper picture,Increased knob setting also results in worse sound.

Television Example: Best

Assuming Picture and Sound are Equally Weighted

Television Example: Best

With Picture is half as important as Sound (for a person with hearing problems)

Four Key Elements of Engineering Problems:

• Change: the situation requires a change.

• Best: the best change is desired...

• Resources: using the available resources.

• Uncertainty: knowledge about the situation is incomplete and sometimes inconsistent

Available Resources

• Tangible Resources– Money available for project– Time to complete project– Raw materials like steel, concrete, silicon– Computer resources– Number and education of engineers

• Intangible Resources– Past experience with similar projects– Engineer’s interests, passions, etc.

Time as a Resource

• Problem: estimate number of ping-pong balls that can fill the room in– 60 seconds– 2 days– Unlimited time

• Each time limit defines a new engineering problem because the time resource is different

• Each solution would be valid from an engineering point of view because it was done within the time constraints imposed.

Four Key Elements of Engineering Problems:

• Change: the situation requires a change.

• Best: the best change is desired...

• Resources: using the available resources.

• Uncertainty: knowledge about the situation is incomplete and sometimes inconsistent

Uncertainty

• Engineers are asked to find a solution to a problem while lacking complete information

• In Change: both the starting and ending points (A & B) are not fully known

• Resources: intangible resources cannot be quantified, yet they affect the outcome

• Best: the best design is not always clear, best for whom?

What is an Engineer?

• An Engineer is not defined by her product– Electrical Engineer– Computer Engineer– Mechanical Engineer

• An engineer is defined by her method– Finding the best change, using available

resources in an environment of uncertainty

• Engineering Degree great training for…– Business, Medicine, Law, Politics, Development