148
Chapter 3
rication become critical in holding down costs. In power units the emissions
due to burning of fossil fuel becomes a challenge and are not readily solved.
Vibration becomes a problem.
1. Criterion function
Maximize performance
Minimize cost
2. Function constraints
All equations describing the system
3. Regional constraints
Volume and weight
Emissions
D. Instruments and Optical Sights
The operating
character
of the main equipment (tanks,
ships,
helicopters... ) is important and becomes a design parameter for the auxiliary equipment. Servo systems that control them have natural frequencies
generating instabilities in the system. The design criterion is based on frequency and small deflections and rotations to minimize instrument and sight
errors. Note: With this criterion the stress is seldom large and does not present a problem but is present mostly in the computation of frequency
and optical errors.
1. Criterion function
Maximize functional performance
Minimize weight as unit must fit in a confined space
Minimize cost but not sacrifice performance
2. Functional constraints
Frequencies, deflections, and functional performance are critical
3. Regional constraints
Sizes and weight
Optical rotational and deflection limits
E. Buildings or Bridges
The design criterion requires that on unsupported spans, deflections are less
than L/360 where "L" is in inches (keeps drywall, tile, etc. from cracking).
Bridges are arched to minimize deflections (imagine watching a car or truck
in front of you sinking relative to you on a bridge and what your reaction
would be!). Buckling and wind loads affect building complexes and bridges.
Earthquakes also are a major concern, such as the 1994 Northridge
earthquake which cracked many welded joints in steel structures (the fixes
Chapter 3
rication become critical in holding down costs. In power units the emissions
due to burning of fossil fuel becomes a challenge and are not readily solved.
Vibration becomes a problem.
1. Criterion function
Maximize performance
Minimize cost
2. Function constraints
All equations describing the system
3. Regional constraints
Volume and weight
Emissions
D. Instruments and Optical Sights
The operating
character
of the main equipment (tanks,
ships,
helicopters... ) is important and becomes a design parameter for the auxiliary equipment. Servo systems that control them have natural frequencies
generating instabilities in the system. The design criterion is based on frequency and small deflections and rotations to minimize instrument and sight
errors. Note: With this criterion the stress is seldom large and does not present a problem but is present mostly in the computation of frequency
and optical errors.
1. Criterion function
Maximize functional performance
Minimize weight as unit must fit in a confined space
Minimize cost but not sacrifice performance
2. Functional constraints
Frequencies, deflections, and functional performance are critical
3. Regional constraints
Sizes and weight
Optical rotational and deflection limits
E. Buildings or Bridges
The design criterion requires that on unsupported spans, deflections are less
than L/360 where "L" is in inches (keeps drywall, tile, etc. from cracking).
Bridges are arched to minimize deflections (imagine watching a car or truck
in front of you sinking relative to you on a bridge and what your reaction
would be!). Buckling and wind loads affect building complexes and bridges.
Earthquakes also are a major concern, such as the 1994 Northridge
earthquake which cracked many welded joints in steel structures (the fixes