System Synthesis + Design Flashcards
True or False: system synthesis is used to translate a functional architecture into and optimized physical software architecture.
True
Modular designs have low ____, and high _____.
Coupling, Cohesion
Modular designs have ____ coupling and ____ high cohesion. (High or Low)
Low, High
True or False: Robust designs exclusively meet a highly specific set of requirements.
False:
Robust designs generally meet a wide range of requirements.
What is the general systems engineering process?
- Requirements analysis
- Functional Allocation/Analysis
- Synthesis/Design
- Overall Analysis, Optimization, and Control.
Systems synthesis creates a ___ for every WHAT and HOW WELL.
HOW
True or False: Synthesis is generally NOT an iterative process.
False
Come on, everything in engineering centers around repetitiveness and iterativity.
A ______ solution considers overall system risk, cost, technical maturity, and robustness for each possible subsystem combination.
Balanced
List the Synthesis + Design Steps:
- Functional Analysis
- Allocated (derive) performance and resource reqs
- Define Alternatives (physical and software)
- Assess maturity levels of technology
- Define interfaces
- Estimate performance of combinations
- Use performance-resource curves to identify break points
- Determine driving reqs and reallocate if necessary
- Select preferred design architecture, implementation plans, allocations, and expectations.
Functional Analysis Steps:
- Define system reqs
- Functional Decomp
- Create FFBD
- Create TLA and assess functional durations
True or False: Different subsystems designs don’t typically have different performance/resource allocations.
False, duh
True or False: the first resource/performance allocations are usually optimal.
False, sub-optimal ITERATE
When defining subsystem alternatives: you should start with a comparable subsystem for comparison
Yes
What is TRL?
Technology Readiness Level:
a commonly used measure of technical maturity
True or False: Schematic Block Diagrams are not primarily used to check for redundancy, and completeness.
False, they are.
When defining interfaces, we should develop these two diagrams:
________
_________
- N-Squared Diagram
2. Schematic Block Diagram
True or False: cost utility curves have an asymptote
True
True or False: increasing budget proportionally increases performance.
False, the curve has rate decay to zero
The ____ _____ are those that are the most difficult to meet.
Driving Requirements
Difference between mission requirements and allocated/derived requirements:
Mission Requirements (driving):
- cannot be varied
- cannot be optimized
- ex: the space flight system shall have a mass of no more the 5500 kg.
Derived Requirements:
- can be varied without necessarily changing the performance
- Can be reallocated for performance enhancement
- ex: The communications subsystem shall have a mass of no more than 90 kg. (fraction of system mass and may be changed, not total system mass - driving if a constraint)
What is an MOE?
Measure of Effectiveness:
Metric used to assess risk, performance, lifecycle implications, and customer priorities to support decision making.
True or False: better is not the enemy of good enough.
FALSE:
Better wants to kill good enough with an axe
A good way to seek optimal system design is to ____ all subsystems _____.
Stress/test/push, equally
True or False: it is inadvisable to try and share the developmental ‘pain’ between the subsystems during synthesis.
FALSE
We want to spread the pain like peanut butter over that shit.
When seeking ‘balanced’ systems solutions: good _____ is required to acknowledge common goals of all team members.
Communication
List 4 Good Synthesis Heuristics:
- Low Coupling
- High Cohesion
- Low Connectivity
- Magical 7
Define: Low Coupling
Choosing subsystem boundaries so that each can be implemented independently.
Define: High Cohesion
Grouping strongly related functions, segregate the unrelated ones.
Define: Low Connectivity
Reducing the overall complexity and number of interfaces present.
Define: Magical 7
Each level of a partitioned hierarchy should have 7 +/- 2 elements.
True or False: it is generally easy to determine the boundary between hardware and software functions
False
True or False: finding the boundary between data management with spacecraft and ground control is very difficult.
True
A robust design reduces the effects of _____ and _______.
Uncertainty, variability
A robust design ____ the effects of uncertainty or variability without ______ the uncertainty or variability itself. (same word)
Reduces
What does sensitivity analysis do?
Assesses the performance of an element with variable input.
The following is an example of a robust design:
Input varies from 90 to 120V
Output varies from 16 to 20V
Not Robust
Highly sensitive when looking at percentage fluctuations of the output.
The following is an example of a robust design:
Input varies from 90 to 120V
Output varies from 17.9 to 18.05V
Not Robust
Percentage change of output very low.
Robust designs ______ utility to gain performance over a wide range or resources & environments.
Sacrifice
______ is a measure of the ability of a system to absorb changes in requirements, constraints or failures while reducing the impacts on the performance, functionality or composition of the mission or system.
Robustness
System synthesis produces a _____ architecture from the _______ architecture.
Physical, Functional
Name a good way to seek optimal design:
Stressing all subsystems equally.
True or False: Maintaining a decision database and formally reviewing it at milestones is a part of functional analysis.
False:
This is a part of system synthesis and design
We can ______ resources/performance to manage and meet the driving requirements.
Reallocate
True or False: subsystems should have high complexity, low cohesion, and low connectivity.
False
low comp, high cohesion
