Lecture 1: Introduction

Lecture 1: Introduction

Content • Course objectives • Systems Engineering (SE) definitions • Benefits of SE • A Universal Ontology for SE • System, Function, and Concept

Course Objectives • Study about systems and their development: • How to analyze systems • How to model systems • How to architect systems • How to design systems • How to test systems • This is a course about How to think, not What to think • Focus: Model-Based Systems Engineering –MBSE • Via a critical review of OPM Second Edition book

Systems Engineering Defined INCOSE – International Council on Systems Engineering Systems Engineering Handbook

What is Systems Engineering? • Systems Engineering (SE) is a comprehensive approach to the development of any complex, multidisciplinary system. • The quality of the system resulting from SE impacts the cost and value of the entire project.

More Systems Engineering Definitions “The top level process of engineering a system to meet overall requirements.” www.tso.co.uk/demo/itil2/cd/content/ss/ss_apdx_a_02.htm “The application of engineering to solutions of a complete problem in its full environment by systematic assembly and matching of parts in the context of the lifetime use of the system.”www.ichnet.org/glossary.htm Engineering Systems At MIT http://techtv.mit.edu/collections/esd/videos/9379-the-engineering-systems-division-at-mit

Yet another SE Definition “Systems engineering is the branch of engineering concerned with the development of large and complex systems. Systems engineering focuses on the real-world goals for, services provided by, and constraints on such systems; the precise specification of system structure and behavior, and the implementation of these specifications; the activities required in order to develop an assurance that the specifications and real-world goals have been met; the evolution of such systems over time and across system families. It is also concerned with the processes, methods and tools for the development of systems in an economic and timely manner.” http://www.mssl.ucl.ac.uk/syseng/pages/sedef.html

Engineering Systems At MIT Related to systems engineering, which is an important profession and practice, engineering systems is a field of scholarship that includes systems engineering as well as a broader set of disciplines. Engineering systems has an added focus on social, environmental, technological, and political contexts. Watch some of the 7 min. video: http://techtv.mit.edu/collections/esd/videos/9379-the-engineering-systems-division-at-mit

SE and Engineering Systems in Context Society country Engineering Systems • Conceptual modeling is not limited to any of the borders on the left. • It can be applied to systems in any domain and at any level of complexity.

Software Design Mechanics Design Electronics Design System Engineering Phases SYSTEM ENGINEERING DETAILED DESIGN PRODUCTION INTEGRATION TEST • Systems Engineering encompasses: • Requirements engineering • System architecture • Subsystem integration design • System testing design • Project oversight & management Accounts for ~15% of the Development Budget

SYSTEM DESIGN DETAILED DESIGN PRODUCTION INTEGRATION TEST • Mistakes at this stage • affect all downstream phases, • are the most difficult and costly to correct, • determine project cost, timetable, overall success Why is Systems Engineering important? Much of the system or product’s value, cost and risk are determined here.

Better system quality and value Lower cost Shorter time-to-market Traditional Design Risk SYSTEM DESIGN DETAIL DESIGN PRODUCTION INTEGRATION Time TEST Risk Saved Time & Cost “System Thinking” Design Time Potential benefits of Systems Engineering

Total Program Overrun 32 NASA Programs NASA Tracking 1980s % Investment in System Engineering Effort (SEE)

Time-Phased Sensitivity of SE to Total System Lifecycle Cost Commitment to Technology, Configuration, Performance, Cost, etc. % 100 75 Cost Incurred 50 System-Specific Knowledge 25 Ease of Change N E E D Conceptual- Preliminary Design Detailed Design and Development Construction And/or Production System Use, Phase out, and Disposal Commitment, System-Specific Knowledge, and Cost Systems Engineering is important early in a program to influence the design, when incurred costs are low and design changes are easy.

Concept and Technology Development Detailed Design and Development Phase Preliminary System Design Phase Conceptual System Design Phase Systems Engineering High Individual Design Disciplines Design Influence Low Systems Design and Development Progress

Clicker QuestionWhat statement is incorrect? Systems Engineering is multi- and interdisciplinary. Early discovery of design errors saves expenses down the road. Systems Engineering deals only with requirements definitions. Focus on individual disciplines increases as we move from conceptual to detailed design.

Systems Engineering effort improves development quality Cost & schedule improved Hypothesis is supported by the data Optimum Systems Engineering effort is 10-15% Matches data from NASA projects Cost & schedule overruns are minimized Systems Engineering must have its ontology and modeling language! Like any engineering discipline, SE must be based on solid foundations of a modeling language InterimConclusions

Questions?

Benefit and Cost • Benefit is anything that increases the physical or mental well-being of a human or a group of humans. • Benefit usually come at some cost. • Cost is the sum of resources and efforts needed to extract or gain benefit.

Value • Value is benefit at a cost. • Value = Benefit – Cost • If the benefit is larger than the cost, then the value is positive and the cost is worth spending (and vice versa). • Value is subjective – it is in the eyes of the beholder, who is the beneficiary. • Some processes provide value to some beneficiaries. • Such processes are called functions.

Function • A function is a process that delivers value to a beneficiary. • Function is also an attribute of an object, which describes: • the rationale behind the existence of that object • the intent for which it was built • the purpose for which it exists • the goal it serves, or • the set of phenomena or behaviors it exhibits.

Examples of Functions • Function: Print a document. • Function: Frame a picture. • Function: Show the time of day. • Function:Cross a river. • Function: Carry at least 2000 tons of wheat every week across a distance of 400 Km. • Function: Protect a large civilian passenger aircraft from a terrorist missile attack.

Phrasing a Function as a Process • Given a function, we convert it to a processphrasing by using the gerund form at the end of the process name. • Example: • Function: Show the time of day. • Process: Time of Day Showing • Continue the example with these functions • Function: Cross a river. • Function: Carry at least 2000 tons of wheat every week across a distance of 400 Km. • Function: Protect a large civilian passenger aircraft from a terrorist missile attack.

Exercise: Phrasing a Function as a Process • Given a function, convert it to a processphrasing by using the gerund form at the end of the process name. • Function:Cross a river. • Process: • Function: Carry at least 2000 tons of wheat every week across a distance of 400 Km. • Process: • Function: Protect a large civilian passenger aircraft from a terrorist missile attack. • Process:

Exercise • Phrase three functions and their corresponding processes • Function: • Process: • Function: • Process: • Function: Protect a large civilian passenger aircraft from a terrorist missile attack. • Process:

System • Performing a function (and extracting value) requires the operation of some object. • That object is called system. A system is a function-carrying object. The function is the main process the system performs.

Stakeholders: Beneficiary, User, Owner • Beneficiary is the agent (human or group of humans) who benefitsfrom the system’s operation • User, or operator, is the agent who uses and operates the system. • Owner is the agent who orders, acquires, and owns the system. • In small systems, the three are the same. • In large systems, they may be different.

Clicker Question • For which of the following systems the Beneficiary, User, andOwner are different? • Scissors • Car • Lightweight rail • National Missile Defense System

Preliminary Stakeholders Model • Agent: A human or group of humans who handle the process and enable it but are not affected by it. • Denoted by the “black lollipop”. • The double arrow is the effect link – denotes that the process changes the object’s state. • Why is the model not quite correct?

Other Stakeholders • Supplier, Contractor, Subcontractors • Government, Legislator • The Public Specific systems have specific stakeholders. Any more stakeholders? For what systems?

The Three Main System Aspects • Natural and artificial systems alike exhibit three major aspects: • Function: why is the system built; what value is it expected to create? • Structure: what are the system’s parts; how are they combined to provide the function? • Behavior: how does the system operate; how does it change over time?

The Concept Behind a System • Functionpertains to the goal the system is designed for. • In order to function (and provide value) the system must operate based on some idea. • This idea often makes use of the laws of nature and logic in some clever way. • Concept is the idea or working principles underlying the functioning of the system.

Examples for System Concepts • Given a function, propose at least twoconcepts for the system to be architected. • Function: Show the time of day. • Function:Cross a river from one bank to the other. • Function: Carry at least 2000 tons of wheat every week across a distance of 400 Km. • Function: Protect a large civilian passenger aircraft from a terrorist missile attack.

System Architecture System architecture is the overall system’s structure-behaviorcombination, which enables it to attain its function while embodying the architect's concept. • In terms of architecture, conceptis the system architect’s strategy for a system’s architecture. • Examples: • Time Keeping system • River Crossing system

Product vs. Service • Product is a system that is produced by an entity with the intent of selling it to another entity for a profit. • It is a system that has a commercial value to its manufacturer. • Service is a function provided by an entity to another entity for a profit. • It is a function that has a commercial value to its provider • The provided uses a system to provide the service.

Clicker QuestionWhat statement is incorrect? System architecture combines structure and behavior to provide function. Every function has exactly one concept by which it can be achieved. Product is to object what service it to process. For simple systems or products, the owner, user and beneficiary are one and the same.

Questions?

Model: An Abstraction • A model is an abstraction of a system, aimed at understanding, communicating, explaining, or designing aspects of interest of that system. • Modeling approaches and methods: • Natural Language • Mathematics • Graphics-based: sketch, map, drawing … • Physical • …

A Language for Systems Engineering • Systems engineering is the youngest engineering discipline • Like any field of engineering, systems engineering needs to have a language for accurately and unambiguously specifying the system of interest. • In this language, system engineers and other stakeholders should be able to express the design concepts of the system under development in a concise and easily communicable way.

A Universal Ontology for Systems Science & Engineering • Things, and links that connect them, are the elements of any system • Just two types of things: • Object, which can be possibly stateful – a Stateful Object – Object with States • Process • Each thing stands alone as a concept in its own right • Things and states are called entities. • A Link connects two entities. • Links and things are elements

Object An object is a thing that exists or can exist physically or informatically. • The object's existence can be physical or informatical (or conceptual, or logical). • It can be as simple as a block of ice or a record in a file, or as complex as an organization, a human brain, or a galaxy.

Object Naming • Object naming is simple—it is the noun. • It can be a phrases with more than one word: • Apple Cake • Automobile Crash – note that every word is capitalized • The object singularity OPM principle: A name of an object must be singular. Plural has to be converted to singular. • Convert a plural object to singular by adding the word "Set" • Ingredients(e.g., of a Cake) becomes Ingredients Set. • "Set" is an OPM reserved word used for loops and iterations on the set members.

Object State A state is a possible situation at which an object can be, or a value it can assume, for some positive amount of time. • A state does not stand alone • It has a meaning only within, and in the context of, an object. • Examples: • States of the object Organizationcan be private or public • States of the object Recordcan be locked or unlocked • State names are not capitalized • Exercise: Model these examples

Transformation • Transformation is the • creation(generation, construction) ofan object or • consumption(elimination, destruction) of an object or • changingthe state of an object. • Transformation takes a positive amount of time.

Process A process is a thing that transforms an object. In other words: A process is a pattern of objecttransformation. • By definition, a process must be associated with at least one object, the one which the process transforms. • For example • Freezingis a process that creates an Ice Block • Meltingis a process that destroys an Ice Block • Exercise: Model these assertions.

Process Naming • The gerund process naming mode A process name is a phrase whose last word should be the gerund form of a verb, a verb with the "ing" suffix. • If there are several choices, such as in Construction vs. Constructing, the latter is preferable. • This naming convention has two advantages • clarifies the dynamic nature of the process as a thing that happens rather than a thing that exists. • The ingsuffix enables automated detection of processes. • An object name can precede the gerund. • In Engine Igniting, the process Ignitingtransforms the object Engine by changing its state from shut down to running. • Adding an object before the process qualifies the process. • For example, Wall Painting, Roof Painting, and Car Painting are similar yet different processes.

Gerund process naming mode versions • The verb version: the gerund form of the verb • verb + ing, as in Making or Crossing. • The noun-verb version: • noun + verb + ing, as in Cake MakingorRiver Crossing. • The adjective-verb version: • adjective + verb + ing, as in Quick Making or Assisted Crossing. • The adjective-noun-verb version: a concatenation of an adjective with a noun with the gerund • adjective + verb + ing, as in Quick Cake Making or Assisted River Crossing. • In these examples, the adjective qualifies the process (the gerund, which is a noun). • However it can also qualify the object (the noun), as in Sweet Cake Making orWide River Crossing. • Where do we place the adjective of the process if we want also an adjective for the object? QuickSweet Cake Making

The Emergence of MBSE • Systematic specification, analysis, design and implementation of new systems and products are becoming ever more challenging and demanding • Contradicting requirements of shorter time-to-market, rising quality, and lower cost are on the rise. • These realizations have provided the basis for Model-Based Systems Engineering (MBSE) as a foundational field of study within systems engineering.

MBSE Methodology • MBSE calls for the development of a comprehensive methodology, capable of tackling the mounting challenges that the evolution of new systems and products poses. • An MBSE methodology is a collection of related processes, methods, and tools that support systems engineering. • Modeling is a foundational engineering activity in an MBSE methodology. • The evolving model resulting from this activity is a central infrastructural entity • The model supports systems development, evolution, and lifecycle in a “model-based” or “model-driven” context.

Model Based Systems Engineering Benefits • Shared understanding of system requirements and design • Validation of requirements • Common basis for analysis and design • Identification of risks • Basis for managing complex system development • Separation of concerns via multiple views of an integrated model • Support for traceability through hierarchical system models • Facilitation of impact analysis of requirements and design changes • Support for incremental development & evolutionary acquisition • Improved design quality • Reduced errors and ambiguity early on • More complete and consistent representation

Lecture 1: Introduction