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1 – CONCEPT OF SYSTEM
1 – CONCEPT OF SYSTEM
2 – BASIC MODELING TECHNIQUES
3 – CONCEPT OF SYSTEMS ENGINEERING
ISO/IEC 15288 definition
ISO/IEC 15288 definition
A system is a combination of interacting elements organized to achieve one or more stated purposes.
NOTE 1: A system may be considered as a product or as the services it provides.
NOTE 2: In practice, the interpretation of its meaning is frequently clarified by the use of an associative noun, e.g. aircraft system.
A "System" is primarily an abstract concept which includes a purpose (final goal)
A "System" is primarily an abstract concept which includes a purpose (final goal)
It is defined by an intended use (a mission) and a boundary
“A system is
“A system is
a collection of components such as people, hardware, software, materials, procedures or services
that are gathered, and synchronized
so that the mutual interactions, using resources in a given environment
satisfies the needs and expectations
that are derived from the mission and the objectives
* themselves derived from its purpose”.
Purpose : provide people transportation for various destinations
Purpose : provide people transportation for various destinations
Mission : transport people, goods or both, from one point to another
Objectives : 1 to 6 persons at the same time – distances of 30 km max.
The Needs & Requirements" view
The Needs & Requirements" view
Purposes = enrich a nation or sets of people, or allows the exchange of goods, energy and services between humans, etc.
Missions = production of goods or energy, or provision of services, or transportation of goods and humans, or maintenance of products, or disposal of infrastructures, etc.
Objectives = all quantitative and qualitative aspects that are associated to missions: how many goods to produce per day, or how many people to transport per month, or how many students to teach per year, etc.
The logical / functional architecture view
The logical / functional architecture view
high level functions such as "develop new products"; product products; sell products; manage the internal means and make the link with external social administrations and laws, etc.
these functions are decomposed into processes, the processes into activities, the activities in tasks, etc.
a process or an activity is no more than a function
Functional interfaces & limits = the enterprise defines its activities around its core business, subcontracts enabling services to acquire necessary resources and/or subcontracts part of its activities
The physical architecture view
organizational entities of Personnel, Experts, Managers, Executives structured in Services, Departments, Divisions, Corporate, etc.
Each physical entity of the enterprise (Corporate, Divisions, Departments, Services) can be seen in its turn as a system.
At lower levels of decomposition, an entity is physically composed of "human roles", written procedures, tools and other means.
Developing a new product is generally achieved via a "project team" that can be viewed also as a system.
1 – CONCEPT OF SYSTEM
1 – CONCEPT OF SYSTEM
2 – BASIC MODELING TECHNIQUES
3 – CONCEPT OF SYSTEMS ENGINEERING
For analyzing complex systems, we use modeling techniques with formal and graphical representations.
For analyzing complex systems, we use modeling techniques with formal and graphical representations.
A model is a representation of reality (physical phenomenon, process…) with symbols organized according to conventions
A "logical" model is independent from any implementation
A model is a restricting abstraction of a real system
(e.g. : a map, a mock-up, mathematical laws ...)
Restricting the reality is not a model defect; this allows :
to remove useless details for comprehension
to focus on main points
Several models of the same system are necessary for its understanding.
Several models of the same system are necessary for its understanding.
Different model kind:
Semantic model (static aspect, data structure, …)
Functional model (transformation, processing of inputs)
Dynamic model (functions control and linking, state/transition, events)
Temporal model (function execution and decision making within time)
Physical model (components and physical connexions)
Complementary models :
Performances (mock-up)
Human-System interfaces
Dependability ...
We model at least on two levels to understand a system :
To describe the "Needs" within its context (The system as a black box in its operational environment)
The candidate solutions (How the system is built inside)
Set of interrelated of interacting activities which transforms inputs to outputs
Set of interrelated of interacting activities which transforms inputs to outputs
The Systems Engineering Process is not sequential. It is parallel and iterative.
The Systems Engineering Process is not sequential. It is parallel and iterative.
The complex interrelationship between creating and improving models throughout the process of developing and selecting alternatives is a good example of the dynamic nature of the systems engineering process.
NASA
NASA
DOD (US Departement Of Defense):
Documentation Model
IEEE
ISO (International Organization for Standardization)
IEC (International Electrotechnical Committee).
ISO/IEC 15504 / SPICE (Software Process Improvement and Capability dEtermination)
SEI (Software Engineering Institute)
CMMI defines the essential elements of effective processes for engineering disciplines based on best industry experiences.
CMMI defines the essential elements of effective processes for engineering disciplines based on best industry experiences.
CMMI models provide guidance when developing and evaluating processes.
CMMI models are not actually processes or process descriptions.
1 – CONCEPT OF SYSTEM
1 – CONCEPT OF SYSTEM
2 – BASIC MODELING TECHNIQUES
3 – CONCEPT OF SYSTEMS ENGINEERING
Set of interrelated of interacting activities which transforms inputs to outputs
Set of interrelated of interacting activities which transforms inputs to outputs
The Systems Engineering Process is not sequential. It is parallel and iterative.
The Systems Engineering Process is not sequential. It is parallel and iterative.
The complex interrelationship between creating and improving models throughout the process of developing and selecting alternatives is a good example of the dynamic nature of the systems engineering process.
NASA
NASA
DOD (US Departement Of Defense):
Documentation Model
IEEE
ISO (International Organization for Standardization)
IEC (International Electrotechnical Committee).
ISO/IEC 15504 / SPICE (Software Process Improvement and Capability dEtermination)
SEI (Software Engineering Institute)
CMMI defines the essential elements of effective processes for engineering disciplines based on best industry experiences.
CMMI defines the essential elements of effective processes for engineering disciplines based on best industry experiences.
CMMI models provide guidance when developing and evaluating processes.
CMMI models are not actually processes or process descriptions.
A requirement is a condition to be satisfied in order to respond to:
A requirement is a condition to be satisfied in order to respond to:
A contract
A standard
A specification
Any other document and / or model imposed.
User’s Requirements
User’s Requirements
Statements in natural language of the system services.
Described by the user
System Requirements
Structured document setting out detailed description of system services.
Part of the contract
A customer must be able to abort a transaction in progress by pressing the Cancel key instead of responding to a request from the machine.
A customer must be able to abort a transaction in progress by pressing the Cancel key instead of responding to a request from the machine.
The washing machine will be used in the following countries: UK, USA, Europe, Eastern Europe
The System shall provide ........
The System shall provide ........
The System shall be capable of ........
The System shall weigh ........
The Subsystem #1 shall provide ........
The Subsystem #2 shall interface with .....
A good requirement states something that is necessary, verifiable, and attainable
A good requirement states something that is necessary, verifiable, and attainable
To be verifiable, the requirement must state something that can be verified by:
analysis, inspection, test, or demonstration (AIDT)
User Requirement
User Requirement
Minimum levels of noise and vibration are desirable.
System Requirement
Requirement 03320: The noise generated shall not exceed 60 db
Functional requirements
Functional requirements
Functional requirements capture the intended behavior of the system.
This behavior may be expressed as services, tasks or functions the system is required to perform
Non-Functional requirements
All others
Constraints
The System Architecture identifies all the products (including enabling products) that are necessary to support the system and, by implication, the processes necessary for development, production/construction, deployment, operations, support, disposal, training, and verification
The System Architecture identifies all the products (including enabling products) that are necessary to support the system and, by implication, the processes necessary for development, production/construction, deployment, operations, support, disposal, training, and verification
System : Abstraction
System : Abstraction
Functional model
Dynamic model
Semantic Model
Object model
Physical Model
Interfaces Model
Model Views
The Functional Architecture
The Functional Architecture
identifies and structures the allocated functional and performance requirements.
The Physical Architecture
depicts the system product by showing how it is broken down into subsystems and components
Functional : Discover the system functions
Functional : Discover the system functions
Washing Machine
What it does ?
Washes
How it does ?
Agitates
Physical Component : Agitator
How to fly ?
How to fly ?
Look at birds: Physical Model
So I need: Legs, Eyes, Brain, and Wings.
But I can not fly !!!
Why ?
I have to find the flight functional model !
Functional decomposition of flying function:
Functional decomposition of flying function:
Produce horizontal thrust,
Produce vertical lift.
Takeoff and land,
Sense position and velocity,
Navigate,
Physical decomposition:
Physical decomposition:
physical components that birds used to fly: Legs, Eyes, Brain, and Wings.
But can not be applied to system directly
Multi-criteria decision-aiding techniques are available to help discover the preferred alternatives.
Multi-criteria decision-aiding techniques are available to help discover the preferred alternatives.
This analysis should be repeated, as better data becomes available.
Integration means bringing things together so they work as a whole.
Integration means bringing things together so they work as a whole.
Interoperability means loose coupling between components thus flexibility
System-of-systems paradigm deals with temporary loose coupling and emergent behaviour
Integrate :
Integrate :
Build the system
Verification :
Ensures that you built it right
Validation :
Ensures that you built the right thing
Certification :
Ensure that the system is safe
Acceptance :
Ensures that the customer gets what he wants and the company get paid.
