Chapter 2 Flashcards
What is a system?
An organised or complex whole, which consists of interdependent and interacting parts with a specific purpose
An assemblage of thins/parts interacting in a coordinated way
When it is taken apart, it loses its essential property and so do the parts
A system is not the sum of its parts; it is the products of their interactions
3 features of a system
1) The parts of the system affect the system and are affected by it
2) The assemblage of parts does something (serves a purpose)
3) The assemblage is of particular interest
Difference between natural systems and human-made systems
Natural systems came into being by natural processes (e.g., animal organisms and planetary systems)
Human-made systems are designed and operated by people (e.g., communication systems)
Human-made systems need a clear goal/objective
Purpose of projects
Projects exist for the purpose of creating new systems, or changing human-made systems, or altering natural systems
Name the smaller parts that a system can be broken down into
system –> subsystem –> subsubsystem –> … —> element
What is a subsystem?
A system that functions as a component of a larger system
Attributes
Describe or express the condition of a system/subsystem/element in a quantitative or qualitative terms
Purpose of attributes
Designed into the system so that the system performs as required
Environment
anything that influences the behaviour/outcome of the system yet lies beyond the control of the decision maker
Boundary
Separates the system from its environment
Tool used to determine the scope
“Picture Frame” tool
Inside the picture frame = in scope
On the frame = unsure
Outside of the picture frame = outside of the scope
Ask 2 questions to distinguish the system from its environment
1) is it relevant to the system?
2) can the decision maker control it?
What is a system structure?
Name 2 examples
The system structure is the form of the relationship that links elements and subsystems
1) Hierarchical systems
2) Network systems
How do human-made systems achieve their goals/objectives?
By converting inputs into outputs through a defined process
Definition of systems constraints
Limitations that inhibit the ability of a system to reach goals and objectives
Examples of system constraints
time
money
Conflict within a system
Objectives of the subsystems sometimes conflict with each other –> reduces the ability for them or the overall system to realise their objectives
Integration in systems
Removing conflicts between the objectives of subsystems to enable the overall system to meet its objectives
Definition of integration
Designing, implementing, and operating a system to achieve pre-specified objectives through the coordinated functioning of its elements and subsystems is called system integration
Definition of a closed system
Viewed as self-contained
Focusses on the operation, structure, and processes of a system without regard to the environment
Definition of an open system
Interacts with and adapts to its environment
Examples
- human organisations
- social systems
The systems approach
- Acknowledges that the behaviour of any one element affects the behaviour of others and that no single element can perform effectively without help from the others
- Recognises interdependencies and cause-effect relationships among elements
- Keeps focus on the bigger picture and ultimate goal
- Avoids actions that focus exclusively on parts of the system (suboptimal for the total system)
What is the Systems Approach Methodology?
A methodology for solving problems and managing systems
What does the Systems Approach account for?
1) Objectives and the performance criteria of the system
2) Environment and constraints of the system
3) Resources of the system
4) Elements of the system, their functions, attributes, and performance measures
5) Interaction among the system
6) Management of the system
7) Methodology commonly employs models
A model
A simplified representation of the world
It abstracts the essential features of the system under study
A physical model
A scaled-down abstraction of the real system
Includes some aspects of the system and excludes others
e.g., model airplane
A conceptual model
Depicts the elements, structure, and flows in a system in terms of a schematic diagram/mathematical model
e.g., population dynamics schematic
What is the system life cycle?
The basic life cycle of human-designed systems
The series of logical, structured steps called the systems development cycle
Phases of the systems development cycle (systems engineering)
1) Conception
2) Definition
3) Design
4) Development
5) Fabrication
6) Testing
7) Installation or launch
8) Production
9) Operation and Maintenance
10) Enhancement, replacement or termination
Definition of Systems Engineering
The science of designing complex systems in their totality to ensure that the components and subsystems making up the system are designed, fitted together, checked and operated in the most efficient way
What are the 3 dimensions of Systems Engineering?
1) Multidisciplinary time
- -> SE is a multidisciplinary, interdisciplinary, concurrent effort
2) System modularisation
- -> It addresses the system’s structure and elements (its functional and physical design)
3) System life cycle
- -> takes into account the way the system will be produces, operated, maintained, and disposed of
Define dimension 1 of Systems Engineering: Multidisciplinary team
Systems engineers work with the system’s stakeholders to determine their needs and what the system must do to fulfil them
The needs become the basis for defining the system requirements, which specify what the system will do
Define dimension 2 of Systems Engineering: System modularisation
System elements and subsystems are designed to perform the functions necessary to satisfy stakeholder objectives and requirements
Design effort focuses on how the system will meet the requirements
Define dimension 3 of Systems Engineering: System life cycle
Helps ensure that the system will be economical to develop, build, operate, and maintain , and that it will be friendly to users and the environment
Creating a system concept
The process is an iterative cycle of
1) Top-down analysis of details (decomposing system into smaller parts)
2) Bottom-up synthesis (building up and integrating the parts into successively larger parts)
3) Evaluation (checking to see that the results meet the requirements)
