Lecture-03

Question 1

System Life Cycle

Answer 1

Concept Dev > Engineering Dev > Post Development

Question 2

Concept Dev: 3 Steps
1. Needs Analysis
2. Concept Exploration
3. Concept Definition

Answer 2

1. Needs Analysis: System Studies, Tech Assessment and Operational Studies.
2. Concept Exploration: Requirement Studies, Concept Synthesis, Feasibility experiments
3. Concept Definition: Analysis of Alternatives, Functional & Physical Architecture

Question 3

Needs Analysis + Concept Exploration = Feasibility Studies

Answer 3

So, System life cycle starts with Feasibility Studies

Question 4

2nd Stage of Life cycle is Engineering Development. It has 3 parts.

Answer 4

1. Advanced Development
2. Engineering Design
3. Evaluation and Integration

Question 5

2nd Stage of Life cycle is Engineering Development. It has 3 parts.
1. Advanced Development
2. Engineering Design
3. Evaluation and Integration

Answer 5

1. Advanced Development: Risk Management, Subsystem Def, Component Specs.
2. Eng Design: Component Eng, Compo tests, Specialty Tests
3. Eval & Integration: System integration and Testing, Operational Evaluation.

Question 6

2nd Stage of Life cycle is Engineering Development. Its first step Advanced Development finishes with Component Specifications.

Answer 6

In Its second Step (Engineering Design), the specifications are turned into Prototypes (Component testing and engineering)

Question 7

The Last and 3rd Stage of Life Cycle is Post Development.

Answer 7

In Post Development, Operational and Maintenance Documentation and Installation is covered.

Question 8

Evolution of Systems Materialization through System Life Cycle: Slide 14 (Very Important)

Answer 8

For Example, Requirement Analysis and Feasibility are done in Subsystem Level in Concept Exploration Substage.
Concept is validated in Advanced Development Substage in System Level and Specification is defined in Component Level.

Question 9

System Engineering Method has 4 Basic Steps.

Answer 9

I. Requirements analysis : identifies why requirements are needed.
II. Functional definition: translates requirements into functions.
III. Physical definition: synthesizes alternative physical implementations
IV. Design validation: models the system environment

Question 10

First Step of System Engineering Method: Requirements Analysis

(i) Operational Requirements Analysis:
*Understand the operational requirements
*Identify and resolve problems with the operational requirements.

Answer 10

–Conflicts
–Incomplete requirements
–Obviously expensive/impossible
(ii) Provide feedback to the users:
*Request clarifications
*Recommend changes

Question 11

First Step of System Engineering Method: Requirements Analysis
(i) Operational Requirements Analysis: Mission and purpose of the system.

Answer 11

Requirements elicitation: is the practice of researching and discovering the requirements of a system from users, customers, and other stakeholders.
* Users and operators (via market survey and interviews)
* Subject matter experts
* Previous studies and system development efforts
 Requirements analysis:-
*Check if the requirements are “valid”, “feasible”, “vague” or “inconsistent”
*Avoid any “redundant” requirements.

Question 12

Requirements Elicitation Techniques:
1. Interviews
2. Surveys/Questionnaires
3. Document Analysis
4. Observation
5. Brainstorming

Answer 12

6. Prototyping
7. Use Cases
8. Scenarios
9. Workshops
10. Storyboarding

Question 13

2nd Step of System Engineering Method: Functional Definition (there are four steps in sys eng method)

Answer 13

Functional Definition
–Determine System requirements: Go to 1st subsystem level if needed.
–Determine required performance
–Define top level scope of system.

Question 14

2nd Step of System Engineering Method: Functional Definition (there are four steps in sys eng method)

Answer 14

Translate requirements (why) into functions (actions and tasks) that the
system must accomplish (what)
* Partition (allocate) requirements into functional building blocks
* Define interactions among functional elements to lay a basis for their organization into a modular configuration.

Question 15

The distinctions among objectives, requirements and functions are tedious.

Answer 15

Objective : tends to be at higher level
Requirement : tends to be more technical with various types
Function : context of functional build blocks

Question 16

2nd Step of System Engineering Method: Functional Definition.
Definition of performance requirements:
–How well the system should perform its requirements and affect its environment.
–Provide numerical thresholds (should be objective and quantitative)

Answer 16

System performance characteristics:
–Define what the system must do, and how well, but not how the system should do it.
–Define characteristics in engineering terms that can be verified by analytical means or experimental tests.
–If a system possesses the stated characteristics, it will satisfy the operational requirements.

Question 17

2nd Step of System Engineering Method: Functional Definition.
Functions:
Help to interpret the information of operational and performance requirements with more engineering contents.
Help to explore different system concepts.

Answer 17

How to identify system functions-
**Functional media: signals, data, material and energy
**Ask the questions

Question 18

2nd Step of System Engineering Method: Functional Definition.

Functions:

Three function categories: input,
transformative and output.

Answer 18

Input function: the processes of sensing and inputting “functional media” into the system.
Output function: the processes of interpreting, display, synthesizing and output “functional media” out of the system.
Transformative function: transforming inputs to outputs.

Question 19

2nd Step of System Engineering Method: Functional Definition.
How to identify system functions-

Ask question:
Are there operational objectives that require sensing or communications?

Answer 19

Does the system require information to control its operation?

Does system operation involve structures or machinery to house, support, or process materials?
Does the system require energy to activate, move, power, or otherwise provide necessary motion or heat?

Question 20

Functional Media VS Functional Category (Slide 22)

Answer 20

Functional media: signals, data, material and energy.

Function categories: input,
transformative and output.

Question 21

2nd Step of System Engineering Method: Functional Definition.
Functional Analysis:
Steps to Develop functional building blocks-

Answer 21

1. Identification of functional media
2. Identification of functional elements
3. Relation of performance requirements to element attributes
4. Configuration of functional elements
5. Analysis of integration of all external interactions

Question 22

2nd Step of System Engineering Method: Functional Definition.

Answer 22

Functional block diagramming tools:

A representation tool for better communication

Question 23

A Coffee Maker Example How System Works;
Identify Input and Output Functions.
Identify Functions (Input Function, Output Function and Transformative Function.

Answer 23

Make Function List.
Draw Function Block Diagram

Question 24

3rd Step of System Engineering Method: Physical Definition.
—Define candidate implementation concepts(solutions)
*Define functions
*Assign to candidate subsystems
*Define necessary subsystem requirements and performance characteristics.

Answer 24

–Provide feedback to Functional Definition
–System requirements need to change?

So, 3 processes/work.

Question 25

3rd Step of System Engineering Method: Physical Definition.
Synthesize a number of alternate system components representing a variety of design approaches to implementing the required functions.
* Define the most simple practicable interactions and interfaces among structural sub-divisions.

Answer 25

.* Select a preferred approach by trading off a set of predefined
and prioritized criteria (measures of effectiveness [MOE]) to obtain the best “balance” among performance, risk, cost and schedule.
* Elaborate the design to the necessary level of detail

Question 26

4th and last Step of System Engineering Method: Design Validation.
—Validate Requirements
*Ensure requirements are consistent and complete
*Ensure concepts are feasible.

Answer 26

–Provide feedback to Design Implementation.
*Correct deficiencies in candidate concepts
*Change system requirements
*Recommend changes to operational requirements.

Question 27

4th and last Step of System Engineering Method: Design Validation.

Answer 27

Important:
Simulate or test and analyze.
check the solution via experimentation on models