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This work is licensed under Creative Commons Attribution-

  • This work is licensed under Creative Commons Attribution-

  • NonCommercial-ShareAlike 3.0 available online at

  • http://creativecommons.org/licenses/by-nc-sa/3.0/











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.
    • Physical boundary = Partners, customers, suppliers, competitors, geographic levels of intervention (local, national, international), administrations


The "hierarchical" aspect

  • The "hierarchical" aspect

    • 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.





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