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Structure of Complex Systems (Types of Environmental Interactions…
Structure of Complex Systems
Context Diagram
It describes the different ways in which a system interacts with other systems and its environment in general. it helps to:
evalaute and
communicate the boundaries of systems.
identify
A context diagram consists of three basic elements
Interactions
Interactions between the external entities and the system are represented by arrows. Arrowheads represent the direction or flow of a particular interaction.
The System
It is an oval, circle, or rectangle in the middle of the context diagram
Only the name of the system is written within.
This is the single geographic figure.
External Entities
These constitute all entities the system will interact with.
mainly sources for inputs and
destinations of outputs from the system
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External and Internal Interfaces
External interfaces
at the boundaries between the system and other external entites
Internal interfaces
between individual components within the system
A major theme of systems engineering is management of interfaces through:
Identification and description
concept definition phase
coordination and control
engineering development, production
Interaction
Communication between two or more elements in a system. Interactions are effected through the interface connecting the interacting entities.
Physical interface/interaction initiates functional interaction e.g.
[Traction rate/Velocity] Vs [tires of the car on the road]
[Car's travel directions] Vs [driver's hands on the steering]
Functional interactions and physical interfaces
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Interface Elements
Isolaters: Inhibit such interactions; and
Converters: Alter the form of the interaction medium
Connectors: Facilitate transmission of electricity, fluid, force etc between components
Basic Interaction media
mechanical
hydraulic and
electrical
human
Pneumatics
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Types of Environmental Interactions
Quasi-functional interaction
maintenance
Secondary interaction
Indirect non-functional interactions such as:
ambient temperature, Pressure, wind
external sound etc
physical supports
Primary Interaction
Direct interaction with the system's primary functions
outputs
controls (human control interface/autonomous control)
inputs
Functional Interaction (Primary) Environmental
[A passenger aircraft]
[Inputs and Outputs]
Primary function: to transport passengers and their belongings
input
Fuel
Passengers and their luggage
output
Heat
Vibration
Sound
light
[Control Systems]
Flight Control and guidance
Flight Operator
[Lecture Halls]
Inputs and Outputs
Primary function: to cater for academic related activities
inputs
Guest Lecturers etc
Students
Employed Lecturers
Quasi Funtional
Operational Maintenance: System readiness and operational reliability during the operating life.
testing, and
repair requirements
access for monitoring
Secondary Interaction/Non-functional Environmental
Support Systems
Infrastructure to support system's mission
System Housing
provides protection from temperature, humidity, and other external factors.
can occasionally constrain performance if not compatible
Non-Functional/Physical Environmental
Shipping and Handling Environment. Transportation from the manufacturing site to the operating site
Shocks and vibrations
Physical Damages
Inhibitors
Threats: This class of external entities can be man-made or natural.
Corrosive salt water environment for offshore engineering systems, naval fleets
(ATM) criminals
System threats need to be identified early to design counter measures into the system.