Systems Engineering and Life Cycle Processes

What is Systems Engineering?

The purpose of systems engineering

• Systems engineering guides engineers develop complex systems or a system of systems
• It focuses on a system as a whole
• It relies on qualitative on top of quantitative judgments used by electrical, mechanical, chemical or software engineers
• It coordinates the different engineers of different disciplines

A. Kassiakoff, S. Seymour, D. Flanigan, and S. Biemer, “Systems Engineering and the World of Modern Systems”, Systems Engineering and Management, Wiley, 2020, ch. 1, pp. 3.

The qualitative approach

Systems engineering uses a methodical and disciplined approach for the specification, design, development, realization, technical management, operations, and retirement of a system.

Office of the Deputy Director for Engineering, Office of the Under Secretary of Defense for Research and Engineering, December, Systems Engineering Guide, 2021, sec. 1.2, pp. 2 and Figure 1-2 Systems Engineering Processes

The quantitative approach

• Reaches out to all stakeholders
• Quantifies tasks
• Works along with the Configuration Management team
• Works with the Data Management team
• Performs technical reviews
• Works with the Scheduling Team
• Assists with creating the Concept of Operations (ConOps) and System Architecture
• Defines system boundaries
• Performs design trade-off studies

Systems engineering workflow

1. Define stakeholder's needs
2. Derive system requirements
3. Characterize the system context
4. Define the system context
5. Define the expected system behavior
6. Build out the subsystems underneath the parent system
7. Define relationships and values that can be exchanged between subsystems ports, constraints, value properties, interfaces, and flow properties
8. Define actual system behavior using state diagrams, activity diagrams, and parametric diagrams
9. Tie the requirements to the system elements
10. Make sure the containment tree is clean

Systems engineering and project Management

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What is a system?

What is a system?

A system is a member of a set of elements. These member elements include hardware, software, data humans, processes, procedures, facilities, materials, and natural occurring entities such as weather. A System element is a discrete part of a system that can be implemented to fulfill specified requirements.

Systems Engineering Handbook 2.0, Fundamentals of Systems Engineering, https://www.nasa.gov/reference/2-0-fundamentals-of-systems-engineering/, 2025-09-05

System elements

The responsibility of any system element may be delegated to parties through agreement.

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See section 4.1.47 of IEEE 15288-2015

An enabling system

A system that supports the system of interest during its life cycle stages but does not necessarily contribute directly to its function during operation.

Examples include training systems, maintenance systems, and mass-production systems. Every enabling system has a life cycle of its own.

See section 4.1.18 and 5.2.3 of IEEE 15288-2015