Editing Systems engineering (section)

==Concept==
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! style="background:#ccc;"| Some definitions
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| style="text-align: left;" | [[Simon Ramo]], considered by some to be a founder of modern systems engineering, defined the discipline as: "...a branch of engineering which concentrates on the design and application of the whole as distinct from the parts, looking at a problem in its entirety, taking account of all the facets and all the variables and linking the social to the technological."<ref>{{Cite book|title=Conquering Complexity: lessons for defence systems acquisition, The Defence Engineering Group|publisher=[[University College London]]|date=2005}}</ref> — ''Conquering Complexity, 2005.''
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| style="text-align: left;" | "An interdisciplinary approach and means to enable the realization of successful systems"<ref>{{Cite book|title=Systems Engineering Handbook, version 2a|publisher=INCOSE|date=2004}}</ref> — ''[[INCOSE]] handbook, 2004.''
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| style="text-align: left;" | "System engineering is a robust approach to the design, creation, and operation of systems. In simple terms, the approach consists of identification and quantification of system goals, creation of alternative system design concepts, performance of design trades, selection and implementation of the best design, verification that the design is properly built and integrated, and post-implementation assessment of how well the system meets (or met) the goals."<ref>{{Cite book|title=NASA Systems Engineering Handbook|id=SP-610S|date=1995|publisher=[[NASA]]}}</ref> — ''[[NASA]] Systems Engineering Handbook, 1995.''
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| style="text-align: left;" | "The Art and Science of creating effective systems, using whole system, whole life principles" OR "The Art and Science of creating optimal solution systems to complex issues and problems"<ref>{{cite web|url=http://incose.org.uk/people-dkh.htm|title=Derek Hitchins|publisher=INCOSE UK|access-date=2 June 2007}}</ref> — ''Derek Hitchins, Prof. of Systems Engineering, former president of INCOSE (UK), 2007.''
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| style="text-align: left;" |"The concept from the engineering standpoint is the evolution of the engineering scientist (i.e. the scientific generalist who maintains a broad outlook). The method is that of the team approach. On large-scale-system problems, teams of scientists and engineers, generalists as well as specialists, exert their joint efforts to find a solution and physically realize it...The technique has been variously called the systems approach or the team development method."<ref>{{Cite book|title=System Engineering: An Introduction to the Design of Large-scale Systems|last1=Goode|first1=Harry H.|author2=Robert E. Machol|publisher=McGraw-Hill|date=1957|page=8|lccn=56011714}}</ref> — ''Harry H. Goode & Robert E. Machol, 1957.''
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|style="text-align: left;" | "The systems engineering method recognizes each system is an integrated whole even though composed of diverse, specialized structures and sub-functions. It further recognizes that any system has a number of objectives and that the balance between them may differ widely from system to system. The methods seek to optimize the overall system functions according to the weighted objectives and to achieve maximum compatibility of its parts."<ref>{{Cite book|title=Systems Engineering Tools|last=Chestnut|first=Harold|date=1965|publisher=Wiley|isbn=978-0-471-15448-8|url-access=registration|url=https://archive.org/details/systemsengineeri0000ches}}</ref> — ''Systems Engineering Tools by Harold Chestnut, 1965.''
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Systems engineering signifies only an approach and, more recently, a discipline in engineering. The aim of education in systems engineering is to formalize various approaches simply and in doing so, identify new methods and research opportunities similar to that which occurs in other fields of engineering. As an approach, systems engineering is holistic and interdisciplinary in flavor.

===Origins and traditional scope===
The traditional scope of engineering embraces the conception, design, development, production, and operation of physical systems. Systems engineering, as originally conceived, falls within this scope. "Systems engineering", in this sense of the term, refers to the building of engineering concepts.

===Evolution to a broader scope===
The use of the term "systems engineer" has evolved over time to embrace a wider, more holistic concept of "systems" and of engineering processes. This evolution of the definition has been a subject of ongoing controversy,<ref>{{cite conference|title=The Case for Evolving Systems Engineering as a Field within Engineering Systems|first1=Donna|last1=Rhodes|first2=Daniel|last2=Hastings|conference=MIT Engineering Systems Symposium|date=March 2004|citeseerx=10.1.1.86.7496}}</ref> and the term continues to apply to both the narrower and a broader scope.

Traditional systems engineering was seen as a branch of engineering in the classical sense, that is, as applied only to physical systems, such as spacecraft and aircraft. More recently, systems engineering has evolved to take on a broader meaning especially when humans were seen as an essential component of a system. [[Peter Checkland]], for example, captures the broader meaning of systems engineering by stating that 'engineering' "can be read in its general sense; you can engineer a meeting or a political agreement."<ref name="Checkland">{{cite book|last=Checkland|first=Peter|editor-last=Pyster|editor-first=Authur|title=Systems Thinking, Systems Practice|publisher=John Wiley & Sons|date=1999}}</ref>{{Rp|10}}

Consistent with the broader scope of systems engineering, the [[Systems Engineering Body of Knowledge]] (SEBoK)<ref>{{cite book|last=Checkland|first=Peter|editor-last=Pyster|editor-first=Authur|title=Systems Thinking, Systems Practice|publisher=John Wiley & Sons|date=1999}} 2012. Systems Engineering Body of Knowledge. 1.0 ed: Stephens Institute and the Naval Postgraduate School.</ref> has defined three types of systems engineering:
* Product Systems Engineering (PSE) is the traditional systems engineering focused on the design of physical systems consisting of hardware and software.
* Enterprise Systems Engineering (ESE) pertains to the view of enterprises, that is, organizations or combinations of organizations, as systems.
* Service Systems Engineering (SSE) has to do with the engineering of service systems. Checkland defines a service system as a system which is conceived as serving another system.<ref name="Checkland"/> Most civil infrastructure systems are service systems.

===Holistic view===
Systems engineering focuses on analyzing and [[Requirements elicitation|eliciting]] customer needs and required functionality early in the [[development cycle]], documenting requirements, then proceeding with design synthesis and system validation while considering the complete problem, the [[system lifecycle]]. This includes fully understanding all of the [[Project stakeholders|stakeholders]] involved. Oliver et al. claim that the systems engineering process can be decomposed into:
* A ''Systems Engineering Technical Process''
* A ''Systems Engineering Management Process''

Within Oliver's model, the goal of the Management Process is to organize the technical effort in the lifecycle, while the Technical Process includes ''assessing available information'', ''defining effectiveness measures'', to ''create a behavior model'', ''create a structure model'', ''perform trade-off analysis'', and ''create sequential build & test plan''.<ref name="Okk">{{Cite book|last1=Oliver|first1=David W.|author2=Timothy P. Kelliher|author3=James G. Keegan Jr.|date=1997|title=Engineering Complex Systems with Models and Objects|url=https://archive.org/details/engineeringcompl00oliv|url-access=limited|publisher=McGraw-Hill|pages=[https://archive.org/details/engineeringcompl00oliv/page/n100 85]–94|isbn=978-0-07-048188-6}}</ref>

Depending on their application, although there are several models that are used in the industry, all of them aim to identify the relation between the various stages mentioned above and incorporate feedback. Examples of such models include the [[Waterfall model]] and the [[VEE model]] (also called the V model).<ref>{{cite web|url=http://www.gmu.edu/departments/seor/insert/robot/robot2.html|title=The SE VEE|publisher=SEOR, George Mason University|access-date=26 May 2007|archive-url=https://web.archive.org/web/20071018220159/http://www.gmu.edu/departments/seor/insert/robot/robot2.html|archive-date=18 October 2007|df=dmy-all}}</ref>

===Interdisciplinary field===
System development often requires contribution from diverse technical disciplines.<ref>{{Cite book|last1=Ramo|first1=Simon|author2=Robin K. St.Clair|author1-link=Simon Ramo|title=The Systems Approach: Fresh Solutions to Complex Problems Through Combining Science and Practical Common Sense|date=1998|location=Anaheim, California|publisher=KNI|url=http://www.incose.org/ProductsPubs/DOC/SystemsApproach.pdf|archive-date=6 August 2012|access-date=18 August 2007|archive-url=https://web.archive.org/web/20120806055606/http://www.incose.org/ProductsPubs/DOC/SystemsApproach.pdf|url-status=dead}}</ref> By providing a systems ([[holistic]]) view of the development effort, systems engineering helps mold all the technical contributors into a unified team effort, forming a structured development process that proceeds from concept to production to operation and, in some cases, to termination and disposal. In an acquisition, the holistic integrative discipline combines contributions and balances tradeoffs among cost, schedule, and performance while maintaining an acceptable level of risk covering the entire life cycle of the item.<ref>{{Cite book|chapter-url=https://acc.dau.mil/docs/dag_pdf/dag_ch4.pdf| title=Defense Acquisition Guidebook|chapter=4. Systems Engineering|publisher=[[Defense Acquisition University]]|access-date=12 August 2015|title-link=Defense Acquisition Guide}}</ref>

This perspective is often replicated in educational programs, in that systems engineering courses are taught by faculty from other engineering departments, which helps create an interdisciplinary environment.<ref>{{cite web|url=http://systemseng.cornell.edu/people.html|title=Systems Engineering Program at Cornell University|publisher=Cornell University|access-date=25 May 2007}}</ref><ref>{{cite web|url=http://esd.mit.edu/people/faculty.html|title=ESD Faculty and Teaching Staff|publisher=Engineering Systems Division, MIT|access-date=25 May 2007}}</ref>

===Managing complexity===
The need for systems engineering arose with the increase in complexity of systems and projects, in turn exponentially increasing the possibility of component friction, and therefore the unreliability of the design. When speaking in this context, complexity incorporates not only engineering systems but also the logical human organization of data. At the same time, a system can become more complex due to an increase in size as well as with an increase in the amount of data, variables, or the number of fields that are involved in the design. The [[International Space Station]] is an example of such a system.

[[File:STS-134 International Space Station after undocking.jpg|thumb|The [[International Space Station]] is an example of a very complex system requiring systems engineering.]]

The development of smarter control [[algorithms]], [[microprocessor design]], and [[Environmental systems analysis|analysis of environmental systems]] also come within the purview of systems engineering. Systems engineering encourages the use of tools and methods to better comprehend and manage complexity in systems. Some examples of these tools can be seen here:<ref>{{cite web|url=http://systemseng.cornell.edu/CourseList.html|title=Core Courses, Systems Analysis&nbsp;– Architecture, Behavior and Optimization|publisher=Cornell University|access-date=25 May 2007}}</ref>
* ''[[System architecture]]''
* ''[[System model]], [[Scientific modelling|modeling]], and [[simulation]]''
* ''[[Mathematical optimization]]''
* ''[[System dynamics]]''
* ''[[Systems analysis]]''
* ''[[Statistical analysis]]''
* ''[[Reliability engineering]]''
* ''[[Decision making]]''

Taking an [[interdisciplinary]] approach to engineering systems is inherently complex since the [[behavior]] of and interaction among system components is not always immediately [[well defined]] or understood. Defining and characterizing such [[system]]s and subsystems and the interactions among them is one of the goals of systems engineering. In doing so, the gap that exists between informal requirements from users, [[Sysop|operator]]s, [[marketing]] organizations, and [[technical specifications]] is successfully bridged.

===Scope===
[[File:SE activities (en).svg|thumb|left|upright=1.2|The scope of systems engineering activities]]<ref name="SEF01">{{cite web|title=Systems Engineering Fundamentals|url=http://www.dau.mil/publications/publicationsDocs/SEFGuide%2001-01.pdf|year=2001|archive-url=https://web.archive.org/web/20170131231503/http://www.dau.mil/publications/publicationsdocs/sefguide%2001-01.pdf<!--archive url isn't ideal-->|archive-date=2017-01-31|url-status=dead|publisher=Defense Acquisition University Press|language=en}}</ref>

The principles of systems engineering&nbsp;– holism, emergent behavior, boundary, et al.&nbsp;– can be applied to any system, complex or otherwise, provided [[systems thinking]] is employed at all levels.<ref>{{cite web|last=Adcock|first=Rick|url=http://incose.org.uk/Downloads/AA01.1.4_Principles%20&%20practices%20of%20SE.pdf|title=Principles and Practices of Systems Engineering|publisher=INCOSE, UK|access-date=7 June 2007|archive-url=https://web.archive.org/web/20070615160805/http://incose.org.uk/Downloads/AA01.1.4_Principles%20%26%20practices%20of%20SE.pdf|archive-date=15 June 2007|df=dmy-all}}</ref> Besides defense and aerospace, many information and technology-based companies, [[software development]] firms, and industries in the field of [[Electronics & Communications Engineering|electronics & communications]] require systems engineers as part of their team.<ref>{{cite web|url=http://www.gmu.edu/departments/seor/insert/intro/introsal.html|title=Systems Engineering, Career Opportunities and Salary Information|date=1994|publisher=George Mason University|access-date=7 June 2007|archive-url=https://web.archive.org/web/20070922213853/http://www.gmu.edu/departments/seor/insert/intro/introsal.html|archive-date=22 September 2007|df=dmy-all}}</ref>

An analysis by the INCOSE Systems Engineering Center of Excellence (SECOE) indicates that optimal effort spent on systems engineering is about 15–20% of the total project effort.<ref name="SEvalue" /> At the same time, studies have shown that systems engineering essentially leads to a reduction in costs among other benefits.<ref name="SEvalue">{{cite web|url=http://www.incose.org/secoe/0103/ValueSE-INCOSE04.pdf|title=Understanding the Value of Systems Engineering|access-date=7 June 2007|archive-date=15 June 2007|archive-url=https://web.archive.org/web/20070615160805/http://www.incose.org/secoe/0103/ValueSE-INCOSE04.pdf|url-status=dead}}</ref> However, no quantitative survey at a larger scale encompassing a wide variety of industries has been conducted until recently. Such studies are underway to determine the effectiveness and quantify the benefits of systems engineering.<ref>{{cite web|last=Elm|first=Joseph P.|title=Surveying Systems Engineering Effectiveness|url=http://www.splc.net/programs/acquisition-support/presentations/surveying.pdf|publisher=[[Carnegie Mellon University]]|location=Pittsburgh, Pennsylvania|archive-url=https://web.archive.org/web/20070615160805/http://www.splc.net/programs/acquisition-support/presentations/surveying.pdf|archive-date=15 June 2007|access-date=16 March 2023}}</ref><ref>{{cite web|url=http://www.valerdi.com/cosysmo/rvalerdi.doc|title=Systems Engineering Cost Estimation by Consensus|access-date=7 June 2007}}</ref>

Systems engineering encourages the use of [[modeling and simulation]] to validate assumptions or theories on systems and the interactions within them.<ref>{{Cite journal|doi=10.1177/003754970107600207|first1=Andrew P.|last1=Sage|author1-link=Andrew P. Sage|first2=Stephen R.|last2=Olson|title=Modeling and Simulation in Systems Engineering|page=90|volume=76|date=2001|journal=Simulation|url=http://intl-sim.sagepub.com/cgi/content/abstract/76/2/90|archive-url=https://web.archive.org/web/20071021061349/http://intl-sim.sagepub.com/cgi/content/abstract/76/2/90|archive-date=21 October 2007|access-date=2 June 2007|issue=2|s2cid=3016918}}</ref><ref>{{Cite journal|last=Smith|first=E.C. Jr.|title=Simulation in Systems Engineering|journal=IBM Systems Journal|publisher=IBM Research|date=September 1962|volume=1|pages=33–50|doi=10.1147/sj.11.0033|url=http://www.research.ibm.com/journal/sj/011/ibmsj0101D.pdf|archive-url=https://web.archive.org/web/20070604221716/http://www.research.ibm.com/journal/sj/011/ibmsj0101D.pdf|archive-date=4 June 2007|access-date=16 March 2023}}</ref>

Use of methods that allow early detection of possible failures, in [[safety engineering]], are integrated into the design process. At the same time, decisions made at the beginning of a project whose consequences are not clearly understood can have enormous implications later in the life of a system, and it is the task of the modern systems engineer to explore these issues and make critical decisions. No method guarantees today's decisions will still be valid when a system goes into service years or decades after first conceived. However, there are techniques that support the process of systems engineering. Examples include soft systems methodology, [[Jay Wright Forrester]]'s [[System dynamics]] method, and the [[Unified Modeling Language]] (UML)—all currently being explored, evaluated, and developed to support the engineering decision process.