Difference between revisions of "Systems Engineering and Management"

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This part of the SEBoK focuses on the general knowledge of ''how'' systems are engineered. It builds on [[Systems|Part 2]] which discusses ''what'' systems are. Part 3 provides a basis for the engineering of [[Product System (glossary)|product systems (glossary)]],  [[Service System (glossary)|service systems (glossary)]], [[Enterprise System (glossary)|enterprise systems (glossary)]], and [[System of Systems (SoS) (glossary)|systems of systems (glossary)]], as described in [[Applications of Systems Engineering|Part 4]]. Part 3 defines [[Systems Engineering (glossary)|systems engineering (glossary)]] and also provides an overview of the common [[Life Cycle Models|life cycle model]] uses in systems engineering (SE). The commonly-used SE processes are also described, along with references to the common methods, tools, and techniques used within these processes. Finally, the [[Systems Engineering Management|management]] aspects of SE are discussed.
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'''''Lead Authors:''''' Jeffrey Carter and Caitlyn Singam
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Systems Engineering and Management (SE&M) articles provide system lifecycle best practices for defining and executing interdisciplinary processes to ensure that customer needs are satisfied with a technical performance, schedule, and cost compliant solution. The figure below depicts the context of SE&M processes and practices guidance within the SEBoK.
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[[File:SEBoK_Context_Diagram_Inner_P3_Ifezue_Obiako.png|centre|thumb|600x600px|'''Figure 1: SEBoK Part 3 SE&M Context [SEBoK Original]''' for more detail see [[Structure of the SEBoK]]]]
  
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It is important to note that Part 3 provides an overview of how systems are engineered in a generic sense. [[Applications of Systems Engineering|Part 4]] provides specific information on how the principles discussed in Part 3 are applied differently depending on the type of system (product, service, enterprise, or system of systems (SoS)) being engineered. [[Enabling Systems Engineering|Part 5]] then explains how an organization may approach utilizing these principles in a holistic manner. [[Related Disciplines|Part 6]] provides references to other/related disciplines which may be utilized in the various SE processes described in Part 3, but which do not fall under the umbrella of SE.
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The SE&M materials are currently being updated to provide system design practitioners with Digital Engineering [DE] and Model-Based Systems Engineering [MBSE] implementation guidance employing the Systems Modeling Language (SysML).
  
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To download a PDF of Part 3, please [http://www.sebokwiki.org/075/images/0/07/SEBoK075_Part3.pdf click here].
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* DE conducts Agile system-software development based on industry open standards by employing MBSE.
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* MBSE develops and integrates SysML design models with simulation capabilities for cross-domain collaboration across the lifecycle.
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* SysML is an industry standard graphical notation with formal semantics (meaning) to define system requirements, constraints, allocations, behavior and structure characteristics
  
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==Knowledge Areas in Part 3==
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==SE&M Knowledge Areas==
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Each part of the SEBoK is divided into knowledge areas ([[Acronyms|KAs]]), which are groupings of information with a related theme. Part 3 contains the following knowledge areas:
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The SE&M articles are organized into the following Knowledge Areas [KAs].
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*[[Life Cycle Models]]
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*[[Systems Engineering STEM Overview]]
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*[[Concept Definition]]
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*[[Model-Based Systems Engineering (MBSE)]]
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*[[System Definition]]
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*[[Systems Lifecycle Approaches]]
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*[[System Lifecycle Models]]
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*[[Systems Engineering Management]]
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*[[Business and Mission Analysis]]
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*[[Stakeholder Needs Definition]]
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*[[System Architecture Definition]]
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*[[Detailed Design Definition]]
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*[[System Analysis]]
 
*[[System Realization]]
 
*[[System Realization]]
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*[[System Deployment and Use]]
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*[[System Implementation]]
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*[[Systems Engineering Management]]
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*[[System Integration]]
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*[[Product and Service Life Management]]
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*[[System Verification]]
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*[[System Transition]]
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*[[System Validation]]
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*[[System Operation]]
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*[[System Maintenance]]
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*System Specialty Engineering
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*[[Logistics]]
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*[[Service Life Management]]
 
*[[Systems Engineering Standards]]
 
*[[Systems Engineering Standards]]
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The SE&M articles provide exemplar processes and practices which are tailorable for an engineering organization to satisfy strategic business goals and individual project objectives including:
  
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==Systems Engineering Definition==
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*How engineering conducts system development
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There is no community consensus on the definition of "systems engineering"; the term has many different connotations in many different domains. One of the more commonly recognized definitions in the field is that of the International Council on Systems Engineering ([[Acronyms|INCOSE]]):
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*The purpose of each engineering artifact generated
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*How systems are integrated, and requirements verified
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*How new product designs are transitioned to production operations
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*How the resulting system is employed and sustained to satisfy customer needs
  
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<blockquote>''An interdisciplinary approach and means to enable the realization of successful systems. It focuses on defining 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:
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==Systems Engineering & Management Overview==
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*''Operations
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The role of Systems Engineering [SE] is to define system requirements, constraints, allocations, behavior and structure characteristics to satisfy customer needs.  The system is defined in terms of hierarchical structural elements and their behavior interactions.  The interactions include the exchange of data, energy, force, or mass which modifies the state of the cooperating elements resulting in emergent, discrete, or continuous behaviors.  The behaviors are at sequential levels of aggregation [bottoms-up] or decomposition [top-down] to satisfy requirements, constraints, and allocations.  SE collaborates within an integrated product team with electrical, mechanical, software, and specialty engineering to define the subsystem and component detailed design implementations to develop a holistic technical solution.  
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*''Performance
 
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*''Test
 
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*''Manufacturing
 
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*''Cost & Schedule
 
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*''Training & Support
 
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*''Disposal
 
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''Systems engineering integrates all the disciplines and specialty groups into a team effort forming a structured development process that proceeds from concept to production to operation. Systems engineering considers both the business and the technical needs of all customers with the goal of providing a quality product that meets the user needs.''</blockquote> (INCOSE 2010, 1)
 
  
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This definition is frequently referenced throughout the SEBoK. SE is the application of a combination of traditional engineering and holistic systems thinking working ''with'' domain engineering, human sciences, management, and commercial disciplines to support the engineering of one or more systems of interest ([[Acronyms|SoI]]). It may also be an interdisciplinary approach governing the total technical and managerial effort required to transform a set of customer needs, expectations, and constraints into a solution, and to support that solution throughout its life cycle. Each of these perspectives is valuable for gaining a holistic view of SE.
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SE has traditionally applied intuitive domain-specific practices emphasizing processes and procedures with good writing skills to manually organize information in a disparate collection of documents including textual system requirement specifications, analysis reports, system design descriptions, and interface specifications.  Traditional SE is often referred to as a document-centric approach.  System design practitioners have cultivated model-based techniques since the late 1990s to facilitate communications, manage design complexity, improve product quality, enhance knowledge capture and reuse. MBSE is defined as the formalized application of graphical modeling with precise semantic definitions for operational analysis, requirements definition, system design development and verification activities beginning in the conceptual phase and continuing throughout later lifecycle phases [INCOSE, 2015]. MBSE conducts system development employing an engineering ecosystem consisting of commercially available tools to create a system design model with SysML compliant semantics that represents the system requirements, constraints, allocations, behavior and structure characteristics. The system design model provides an Authoritative Source of Truth [ASoT] for the project technical baseline with integrated end-to-end simulation capabilities to evaluate system key performance parameters in digital computing environments.  MBSE includes the creation, development, and utilization of digital design models with domain product-specific analyses including aerospace, automobile, consumer, defense, and software.  
  
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==Generic Systems Engineering Paradigm==
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The recent adoption of DE practices [Roper, 2020] broadens the MBSE transformation based on the following principals:
  
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Figure 1 identifies the general goal of any SE effort; that is, the understanding of stakeholder value, the selection of a specific need, the transformation of that need into a system product or service that provides for the need, and the use of that product or service to provide the stakeholder value. This paradigm has been developed according to the principles of a [[Applying the Systems Approach|systems approach]] as discussed in Part 2. This paradigm was used to establish a basis for the KAs in Part 3 and Part 4 of the SEBoK.  
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* Agile System and Software Development to prioritize capability development and respond to evolving threats, environments, and challenges.
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* Modular Open System Approach [MOSA] to develop product-lines based on industry standards that can adapt to evolving customer needs with new, modified, and existing [reuse] capabilities.
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* Digital Engineering [DE] to develop, integrate, and employ MBSE design models with simulation capabilities to realistically emulate systems in digital computing environments for cross-domain collaboration across the system design development, verification, production, and sustainment lifecycle.
  
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[[File:062211_BL_Paradigm.png|thumb|center|700px|Figure 1. Generic Systems Engineering Paradigm (Figure Developed for BKCASE).]]
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The system design model includes functional, logical, and physical system design representations with capabilities that are integrated with electrical, mechanical, software, and specialty design disciplines for system functional and performance assessments. Design model scripts can export functional (SSS, B1, B2, B5) specifications, interface (IRS, ICD, IDD) specifications, design & requirements traceability reports, and design descriptions (SADD, SSDD, SWDD). The integrated simulations provide a digital twin with digital threads of system key performance parameters to evaluate design alternatives in digital computing environments to discover and resolve design defects before the expense of producing physical prototypes.
  
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On the left hand side of Figure 1, there are three [[System of Interest (SoI) (glossary)|systems of interest (glossary)]] identified in the form of a [[System Breakdown Structure (glossary) |system breakdown structure (glossary)]]. System of interest (SoI) 1 is decomposed into its elements, which in this case are systems as well (SoI 2 and SoI 3). These two systems are composed of [[Element (glossary)|system elements (glossary)]] which are not further refined.
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* Digital threads are analytical frameworks providing end-to-end system simulations to evaluate logical operations and key performance parameters in digital computing environments by exchanging information between different engineering modeling tools across the lifecycle.  Evaluation of the digital thread simulations ensure that requirements, interactions, and dependencies are commonly understood across engineering disciplines.  Design changes are automatically reflected in all design model usages to assess compliance, with any issue(s) flagged for corrective action.
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* Digital twins are authoritative representations of physical systems including the digital thread end-to-end connections with all the data, models, and infrastructure needed to define and optimize a system’s lifecycle digitally. Digital twins enable project team collaboration, system simulation functional performance assessments, design change impact evaluations, and product-line management reuse libraries
  
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On the right-hand side of the figure, each SoI has a corresponding [[Life Cycle Model (glossary)|life cycle model (glossary)]] composed of stages that are populated with processes. These processes are used to define the work to be performed. Note that some of the requirements defined to meet the need are distributed in the early stages of the life cycle for SoI 1, and some to the life cycles of SoI 2 or SoI 3. This decomposition of the system illustrates the fundamental concept of [[Recursion (glossary)|recursion (glossary)]] as defined in the ISO/IEC 15288 standard. That standard is reapplied for each SoI. It is important to note that stakeholder requirements may be allocated to different system elements, which may be integrated in different life cycle stages of any of the three SoIs, but together they form a cohesive system. For example, SoI 1 could be an embedded system composed of a hardware system (SoI 2) composed of a chasis and a motor, and a software system (SoI 3).  
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MBSE enhances the ability to capture, analyze, share, and manage authoritative information associated with the complete specification of a product compared to traditional document-based approaches. MBSE provides the capability to consolidate information in an accessible, centralized source, enabling partial or complete automation of many systems engineering processes, and facilitating interactive representation of system components and behaviors. The legacy SE&M materials are all impacted by the adoption of MBSE practices, and the SEBoK is updating its materials accordingly to reflect best practices and principles in an integrated model-based engineering environment.  The updated materials to specify system behavior and structure characteristics with traceability to the associated requirements are organized in accordance with the ISO/IEC/IEEE-15288:2015 ''Systems Lifecycle Processes'' Standard shown in the figure below.
  
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When performing SE processes in stages, [[Iteration (glossary)|iteration (glossary)]] between stages is often required; e.g., in successive refinement of the definition of the system or in providing an update or upgrade of an existing system. The work performed in the processes and stages can be performed in a [[Concurrent (glossary)|concurrent]] manner within the life cycle of any of the systems of interest and concurrently among the multiple life cycles.
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[[File:15288_Standard_Outline_-_Model.png|thumb|center|750px|'''Figure 2.''' ISO/IEC/IEEE-15288:2015 Standard Outline (SEBoK Original)]]
  
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This paradigm provides a fundamental framework for understanding generic SE (seen in Part 3), as well as for the application of SE to the various types of systems described in [[Applications of Systems Engineering|Part 4]].
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Figure 3 depicts a generic example of the model-based system design process.  The approach is consistent with INCOSE’s Systems Engineering Handbook guidance with the addition of a system design model repository to manage the project technical baseline. The MBSE design process is independent of any specific design methodology (e.g., structured analysis, object orientated, etc.) employed. Each design model element has a single definition with multiple instantiations on various diagrams depicting system structure and behavior characteristics including traceability to the associated requirements. The model-based design process may be tailored for projects dependent on the domain-area, development, and lifecycle approaches.
  
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==Applying Iteration and Recursion to Systems Engineering in the Life Cycle==
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[[File:Model-Based_System_Design_Process_Part3.png|thumb|center|600px|''Figure 3: Model-Based System Engineering Process.'' (SEBoK Original)]]
  
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The concept of iteration is also applied for processes. Figure 2 below gives an example of iteration in three processes as defined in ISO/IEC 15288. The processes in this example are further discussed in the [[System Definition]] Knowledge Area.  
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Product domain-area system design knowledge and expertise are still mandatory with the implementation of an MBSE approach, which employs integrated modeling tools instead of legacy drawing tools (e.g., Powerpoint, Visio), textual-based specifications (e.g., DOORS), and engineering analysis reports and design descriptions (Word).  
  
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[[File:Wiki_CR_Placeholder.png|thumb|center|400px|Figure 2. Example of iterations of processes related to system definition (ISO/IEC 2003,p. 21, Figure 12) Source available at http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=33898]]
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The SE&M model-based system design guidance enables a multi-disciplinary team to manage a project’s technical baseline within a single, consistent, and unambiguous system design model. The integrated MBSE design model contains system functional and logical representations with the physical detailed design implementation to specify, analyze, design, and verify that requirements are satisfied. The guidance defines conventions for developing design models to specify system behavior and structure characteristics with traceability to the project’s requirements. The design models provide a digital authoritative source of truth information repository for a project’s technical baseline. Model simulation with test cases facilitate initial design verification in digital computing environments to discover and resolve design defects before incurring the expense of producing physical prototypes.
  
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The complete definition of a SoI is generally achieved using decomposition layers and [[System Element (glossary)|system elements (glossary)]]. Figure 3 presents a fundamental schema of a system breakdown structure.  
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MBSE practices transform SE from the current document-based approach to employing computer aided design tools comparable to the evolution of the EE, ME, SW, and SP disciplines years ago.  The value-added benefit is employment of integrated modeling tools instead of traditional static drawing tools [e.g., PowerPoint, Visio] for product development, integration, and verification across the system lifecycle. 
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The SE&M model-based system design guidance provides MBSE best practices for implementing a digital engineering strategy to develop system design models for specifying and simulating behavior / structure characteristics with traceability to the associated requirements based on the following principles:
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#Develop, integrate, and employ digital system design models for cross-domain collaboration throughout the product lifecycle [i.e., engineering development, production, and sustainment].
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#Manage product-lines based on industry open standards with libraries of customized variants adapted for customers with new, modified, and existing [reuse] system design capabilities.
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#Maintain a digital authoritative source of truth information repository for each product variant’s approved technical baseline throughout the product lifecycle to facilitate collaboration and inform decision making.
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#Conduct model simulations with verification test cases to evaluate system behavior and structure in digital computing environments to discover design defects before the expense of producing physical prototypes.
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#Define digital threads of technical key performance parameters and synchronize information across SE, EE, ME, SW, and SP design modeling tools to ensure system requirements, interactions, and dependencies are commonly understood.  Design changes are automatically reflected in all model usages across engineering discipline tools and assessed for compliance, with any issue(s) flagged for corrective action.
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#Utilize “Agile” development processes to provide consistent methods for developing system design models and identifying digital threads for data synchronization across engineering disciplines within the integrated model-based engineering environment.
  
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[[File:Wiki_CR_Placeholder.png|thumb|center|400px|Figure 3. Hierarchical decomposition of a system-of-interest (ISO/IEC 2008) Source available at http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=43564]]
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The SE&M model-based system design approach has a theoretical scientific foundation based on the system phenomenon defined by Hamilton’s Principle: a system is composed of hierarchical elements which interact by exchanging data, energy, force, or mass to modify the state of cooperating elements resulting in emergent, discrete, or continuous behaviors at progressive levels of aggregation or decomposition as shown in Figure 4.
  
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In each decomposition layer and for each system, the [[System Definition]] processes are applied recursively because the notion of a system is recursive; the notions of a SoI, system, and system element are based on the same concepts (see [[Systems|Part 2]]). Figure 4 shows an example of the recursion of three processes as defined in ISO/IEC 15288.
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[[File:The_System_Phenomenon.png|thumb|center|750px|''Figure 4: The System Phenomenon – Hamilton’s Principle.'' (SEBoK Original)]]
  
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[[File:Wiki_CR_Placeholder.png|thumb|center|400px|Figure 4. Recursion of processes on layers (ISO/IEC 2003, p.20, Figure 11) Source available at http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=33898]]
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==References==
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===Citations===
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OMG Systems Modeling Language [SysML®] Standard – v1.6, November 2019
  
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==Value of Ontology Concepts for Systems Engineering==
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INCOSE. 2015. ''[[INCOSE Systems Engineering Handbook|Systems Engineering Handbook]] - A Guide for System Life Cycle Processes and Activities'', version 4.0. Hoboken, NJ, USA: John Wiley and Sons, Inc, ISBN: 978-1-118-99940-0.
  
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Ontology is the set of entities presupposed by a theory (Collins English Dictionary). SE, and in particular system development, is based on concepts related to mathematics and proven practices. A SE ontology can be defined considering the following path.
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Roper, W. 2020. ‘’There is No Spoon: The New Digital Acquisition Reality.’’ Arlington, VA: US Space Force, US Air Force, Assistant Secretary of the Air Force. 07 October 2020. Accessed May 25, 2023. Available at https://software.af.mil/wp-content/uploads/2020/10/There-Is-No-Spoon-Digital-Acquisition-7-Oct-2020-digital-version.pdf.
  
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SE provides engineers with an approach based on a set of [[System Concepts|concepts]] (i.e., stakeholder, requirement, function, scenario, system element, etc.) and generic processes. Each process is composed of a set of activities and tasks gathered logically around a theme or a purpose. A process describes “what to do” using the concepts. The implementation of the activities and tasks is supported by methods and modeling techniques, composed themselves of elementary tasks; they describe the “how to do” of SE. The activities and tasks of SE are transformations of generic data using the predefined concepts. Those generic data are called entities, classes, or types. Each ''entity'' is characterized by specific ''attributes'', and each attribute can get different values. All along their execution, the activities and tasks of processes, methods, and modeling techniques exchange instances of generic entities according to logical ''relationships''. These relationships allow the engineer to link the entities between themselves (traceability) and to follow a logical sequence of the activities and the global progression (engineering management). Cardinality is associated with every relationship, expressing the minimum and maximum number of entities in order to make the relationship valid. Additional information may be found in ''Engineering Complex Systems with Models and Objects'' (Oliver, Kelliher, and Keegan 1997).
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ISO/IEC/IEEE 15288:2015. ''Systems and Software Engineering -- System Life Cycle Processes''. Geneva, Switzerland: International Organization for Standardization / International Electrotechnical Commissions / Institute for Electrical and Electronics Engineers. ISO/IEC/IEEE 15288:2015.
  
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The set of SE entities and their relationships form an ontology, also often called an engineering meta-model. Such an approach is used and defined in the standard (ISO 2007). There are many benefits to using an ontology. The ontology allows or forces
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Schindel, B. 2016. “Got Phenomena? Science-Based Disciplines for Emerging Systems Challenges,” International Council on Systems Engineering (INCOSE), 2016 INCOSE International Symposium Proceedings, Edinburgh, Scotland.
  
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*the use of a standardized vocabulary, with carefully chosen names that avoid the use of synonyms in the processes, methods, and modeling techniques;
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Schindel, B. 2018. “The System Phenomenon, Hamilton’s Principle, and Noether’s Theorem as a Basis for System Science,” International Council on Systems Engineering (INCOSE), 2018 INCOSE International Workshop Proceedings, Torrance, California.
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*reconciliation of the vocabulary used in different modeling techniques and methods;
 
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*the automatic appearance of the traceability of requirements when implemented in databases, SE tools or workbenches, and also the quick identification of the impacts of modifications in the engineering data set;
 
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*checks of the consistency and completeness of engineering data; etc.
 
  
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Readers are encouraged to read the "ontology" discussions embedded within articles in Part 3. Reviewer comments regarding ontology are encouraged as they will be particularly helpful for the development of version 1.0 of the SEBoK.
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===Primary References===
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INCOSE. 2015. ''[[INCOSE Systems Engineering Handbook|Systems Engineering Handbook]] - A Guide for System Life Cycle Processes and Activities'', version 4.0. Hoboken, NJ, USA: John Wiley and Sons, Inc, ISBN: 978-1-118-99940-0.
  
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==Terminology: Process, Architecture and Requirement ==
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ISO/IEC/IEEE. 2015. [[ISO/IEC/IEEE 15288| Systems and Software Engineering -- System Life Cycle Processes]]. Geneva, Switzerland: International Organization for Standardization / International Electrotechnical Commissions. ISO/IEC/IEEE 15288:2015.
  
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There are terms with multiple definitions used in this Part 3 and the rest of the SEBOK.   Understanding how and where they are used is important. This section will disambiguate them for different contexts within SEBOK to minimize confusion.
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===Additional References===
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U.S. DOD. 2018. ‘’Digital Engineering Strategy.’’ Arlington, VA: Office of the Deputy Assistant Secretary of Defense for Systems Engineering. June 2018.
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The terms ''process'', ''architecture'', and ''requirement'' will be defined in general, partially elaborated and outlined how they are used in different parts of SEBOK for further reference.
 
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'''Process'''
 
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A process is a series of actions or steps taken in order to achieve a particular end; as a verb it is the performing of the operations. Processes can be performed by humans or machines transforming inputs into outputs.
 
  
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In SEBOK processes are interpreted in several ways such as technical, lifecycle, business, or manufacturing flow processes.  Many of the Part 3 sections are structured along technical processes (e.g. design, verification), but [[Life Cycle Models]] applies the concept at the high level of a program lifecycle sequence (e.g. RUP, VEE model, etc.).
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Wasson, C. 2006. System Analysis, Design, and Development – Concepts, Principles, and Practices.’’ Hoboken, NJ: John Wiley & Sons.
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[[Applications of Systems Engineering|Part 4: Applications of Systems Engineering]] and [[Enabling Systems Engineering|Part 5: Enabling Systems Engineering]]  use processes referring to services and business enterprise operations.  See [[Process (glossary)]] for various interpretations of the term.  
 
  
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'''Architecture'''
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Madni, A. M. and Sievers, M. 2018. ''Model‐based systems engineering: Motivation, current status, and research opportunities'', Systems Engineering. 2018; 21: 172– 190. <nowiki>https://doi.org/10.1002/sys.21438</nowiki>
  
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An architecture is the organizational structure of a system, whereby the system can be defined in different contexts. Architecting is the art or practice of designing the structures.
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Estefan, J. 2008. ''A Survey of Model-Based Systems Engineering (MBSE) Methodologies'', rev, B. Seattle, WA: International Council on Systems Engineering.  INCOSE-TD-2007-003-02. Accessed April 13, 2015. Available at http://www.omgsysml.org/MBSE_Methodology_Survey_RevB.pdf.  
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Architectures can apply for a system, product, enterprise, or service. For example, Part 3 mostly considers product related architectures that systems engineers create, but an enterprise architecture describes the structure of an organization.  [[Enabling Systems Engineering|Part 5: Enabling Systems Engineering]] interprets enterprise architecture as much broader than an IT system used across an organization, which is a specific instance of an architecture.  More complete definitions are in [[Architecture (glossary)]].  
 
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Related to architectures are frameworks, which are ways of representing architectures. The terms architecture framework and architectural framework both refer to the same. Examples include DoDAF, MoDEF for representing systems in defense applications, the TOGAF open group architecture framework, and the Federal Enterprise Architecture Framework (FEAF) for information technology acquisition, use and disposal. See [[Framework (Glossary)]] for more examples.
 
  
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'''Requirement'''
 
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A requirement is something that is needed or wanted, so it isn’t compulsory in all circumstances.  Requirements may refer to product or process characteristics and constraints.  Different understandings of requirements depend on process state, level of abstraction and type (e.g. functional, performance, constraint).  An individual requirement may also have multiple interpretations over time.
 
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[[System Definition]] has further descriptions of requirements and their types (e.g. system requirement, stakeholder requirement, derived requirement).  It discusses how different process roles or states, levels, and the nature of requirements matter in understanding what a requirement is.  Also see [[Requirement (glossary)]].
 
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Furthermore, these terms are intertwined and linked in additional concepts.  For example, processes are used to generate architectures and requirements.  Processes are architectures themselves, since the activities form a structure with connections between them.  There are process and architecture requirements.  A requirement depends on the process state.  These are some of the ways the terms and concepts tie together in systems engineering.
 
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==Mapping of Topics to ISO/IEC 15288, System Life Cycle Processes==
 
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Figure 5, below, shows the relative position of the Technical Knowledge Areas (KA) of the SEBoK with respect to the processes as stated in the ISO/IEC 15288 (2008) standard.
 
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[[File:SEBoKv05_KA-SystDef_Mapping_of_technical_topics_of_Know_080711.png|thumb|center|600px|center|Figure 5. Mapping of technical topics of Knowledge Areas of SEBoK with ISO/IEC 15288 Technical Processes (Figure Developed for BKCASE)]]
 
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==References==
 
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===Works Cited===
 
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Collins English Dictionary, s.v. "Ontology." 2011.
 
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INCOSE. 2011. ''Systems Engineering Handbook'', version 3.2.1.  San Diego, CA, USA: International Council on Systems Engineering (INCOSE).
 
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ISO/IEC. 2003. ''Systems Engineering — A Guide for The Application of ISO/IEC 15288 System Life Cycle Processes.'' Geneva, Switzerland: International Organization for Standardization (ISO)/International Electronical Commission (IEC), ISO/IEC 19760:2003 (E).
 
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ISO/IEC 2008. ''Systems and Software Engineering -- System Life Cycle Processes''. Geneva, Switzerland: International Organisation for Standardisation / International Electrotechnical Commissions / Institute for Electrical and Electronics Engineers. ISO/IEC/IEEE 15288:2008.
 
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ISO. 2007. ''Systems Engineering and Design.'' Geneva, Switzerland: International Organization for Standardization (ISO). ISO 10303-AP233.
 
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Oliver, D., T. Kelliher, and J. Keegan. 1997. ''Engineering Complex Systems with Models and Objects''. New York, NY, USA: McGraw-Hill.
 
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===Primary References===
 
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ISO/IEC 2008. [[ISO/IEC/IEEE 15288| Systems and Software Engineering -- System Life Cycle Processes]]. Geneva, Switzerland: International Organisation for Standardisation / International Electrotechnical Commissions. ISO/IEC/IEEE 15288:2008.
 
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INCOSE. 2011. [[INCOSE Systems Engineering Handbook | Systems Engineering Handbook]], version 3.2.1. San Diego, CA, USA: International Council on Systems Engineering (INCOSE).
 
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===Additional References===
 
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No additional references have been identified for version 0.75.  Please provide any recommendations on additional references in your review.
 
 
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<center>[[Dynamically Changing Systems|< Previous Article]] | [[SEBoK Table of Contents|Parent Article]] | [[Life Cycle Models|Next Article >]]</center>
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<center>[[Applying the Systems Approach|< Previous Article]] | [[SEBoK Table of Contents|Parent Article]] | [[Systems Engineering STEM Overview|Next Article >]]</center>
  
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<center>'''SEBoK v. 2.9, released 20 November 2023'''</center>
  
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[[Category: Part 3]][[Category:Part]]
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[[Category: Part 3]]
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{{DISQUS}}
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[[Category:Part]]

Latest revision as of 23:42, 18 November 2023

Lead Authors: Jeffrey Carter and Caitlyn Singam

Systems Engineering and Management (SE&M) articles provide system lifecycle best practices for defining and executing interdisciplinary processes to ensure that customer needs are satisfied with a technical performance, schedule, and cost compliant solution. The figure below depicts the context of SE&M processes and practices guidance within the SEBoK.

Figure 1: SEBoK Part 3 SE&M Context [SEBoK Original] for more detail see Structure of the SEBoK

The SE&M materials are currently being updated to provide system design practitioners with Digital Engineering [DE] and Model-Based Systems Engineering [MBSE] implementation guidance employing the Systems Modeling Language (SysML).

  • DE conducts Agile system-software development based on industry open standards by employing MBSE.
  • MBSE develops and integrates SysML design models with simulation capabilities for cross-domain collaboration across the lifecycle.
  • SysML is an industry standard graphical notation with formal semantics (meaning) to define system requirements, constraints, allocations, behavior and structure characteristics

SE&M Knowledge Areas

The SE&M articles are organized into the following Knowledge Areas [KAs].

The SE&M articles provide exemplar processes and practices which are tailorable for an engineering organization to satisfy strategic business goals and individual project objectives including:

  • How engineering conducts system development
  • The purpose of each engineering artifact generated
  • How systems are integrated, and requirements verified
  • How new product designs are transitioned to production operations
  • How the resulting system is employed and sustained to satisfy customer needs

Systems Engineering & Management Overview

The role of Systems Engineering [SE] is to define system requirements, constraints, allocations, behavior and structure characteristics to satisfy customer needs. The system is defined in terms of hierarchical structural elements and their behavior interactions. The interactions include the exchange of data, energy, force, or mass which modifies the state of the cooperating elements resulting in emergent, discrete, or continuous behaviors. The behaviors are at sequential levels of aggregation [bottoms-up] or decomposition [top-down] to satisfy requirements, constraints, and allocations. SE collaborates within an integrated product team with electrical, mechanical, software, and specialty engineering to define the subsystem and component detailed design implementations to develop a holistic technical solution.

SE has traditionally applied intuitive domain-specific practices emphasizing processes and procedures with good writing skills to manually organize information in a disparate collection of documents including textual system requirement specifications, analysis reports, system design descriptions, and interface specifications. Traditional SE is often referred to as a document-centric approach. System design practitioners have cultivated model-based techniques since the late 1990s to facilitate communications, manage design complexity, improve product quality, enhance knowledge capture and reuse. MBSE is defined as the formalized application of graphical modeling with precise semantic definitions for operational analysis, requirements definition, system design development and verification activities beginning in the conceptual phase and continuing throughout later lifecycle phases [INCOSE, 2015]. MBSE conducts system development employing an engineering ecosystem consisting of commercially available tools to create a system design model with SysML compliant semantics that represents the system requirements, constraints, allocations, behavior and structure characteristics. The system design model provides an Authoritative Source of Truth [ASoT] for the project technical baseline with integrated end-to-end simulation capabilities to evaluate system key performance parameters in digital computing environments. MBSE includes the creation, development, and utilization of digital design models with domain product-specific analyses including aerospace, automobile, consumer, defense, and software.

The recent adoption of DE practices [Roper, 2020] broadens the MBSE transformation based on the following principals:

  • Agile System and Software Development to prioritize capability development and respond to evolving threats, environments, and challenges.
  • Modular Open System Approach [MOSA] to develop product-lines based on industry standards that can adapt to evolving customer needs with new, modified, and existing [reuse] capabilities.
  • Digital Engineering [DE] to develop, integrate, and employ MBSE design models with simulation capabilities to realistically emulate systems in digital computing environments for cross-domain collaboration across the system design development, verification, production, and sustainment lifecycle.

The system design model includes functional, logical, and physical system design representations with capabilities that are integrated with electrical, mechanical, software, and specialty design disciplines for system functional and performance assessments. Design model scripts can export functional (SSS, B1, B2, B5) specifications, interface (IRS, ICD, IDD) specifications, design & requirements traceability reports, and design descriptions (SADD, SSDD, SWDD). The integrated simulations provide a digital twin with digital threads of system key performance parameters to evaluate design alternatives in digital computing environments to discover and resolve design defects before the expense of producing physical prototypes.

  • Digital threads are analytical frameworks providing end-to-end system simulations to evaluate logical operations and key performance parameters in digital computing environments by exchanging information between different engineering modeling tools across the lifecycle. Evaluation of the digital thread simulations ensure that requirements, interactions, and dependencies are commonly understood across engineering disciplines. Design changes are automatically reflected in all design model usages to assess compliance, with any issue(s) flagged for corrective action.
  • Digital twins are authoritative representations of physical systems including the digital thread end-to-end connections with all the data, models, and infrastructure needed to define and optimize a system’s lifecycle digitally. Digital twins enable project team collaboration, system simulation functional performance assessments, design change impact evaluations, and product-line management reuse libraries

MBSE enhances the ability to capture, analyze, share, and manage authoritative information associated with the complete specification of a product compared to traditional document-based approaches. MBSE provides the capability to consolidate information in an accessible, centralized source, enabling partial or complete automation of many systems engineering processes, and facilitating interactive representation of system components and behaviors. The legacy SE&M materials are all impacted by the adoption of MBSE practices, and the SEBoK is updating its materials accordingly to reflect best practices and principles in an integrated model-based engineering environment.  The updated materials to specify system behavior and structure characteristics with traceability to the associated requirements are organized in accordance with the ISO/IEC/IEEE-15288:2015 Systems Lifecycle Processes Standard shown in the figure below.

Figure 2. ISO/IEC/IEEE-15288:2015 Standard Outline (SEBoK Original)

Figure 3 depicts a generic example of the model-based system design process. The approach is consistent with INCOSE’s Systems Engineering Handbook guidance with the addition of a system design model repository to manage the project technical baseline. The MBSE design process is independent of any specific design methodology (e.g., structured analysis, object orientated, etc.) employed. Each design model element has a single definition with multiple instantiations on various diagrams depicting system structure and behavior characteristics including traceability to the associated requirements. The model-based design process may be tailored for projects dependent on the domain-area, development, and lifecycle approaches.

Figure 3: Model-Based System Engineering Process. (SEBoK Original)

Product domain-area system design knowledge and expertise are still mandatory with the implementation of an MBSE approach, which employs integrated modeling tools instead of legacy drawing tools (e.g., Powerpoint, Visio), textual-based specifications (e.g., DOORS), and engineering analysis reports and design descriptions (Word).

The SE&M model-based system design guidance enables a multi-disciplinary team to manage a project’s technical baseline within a single, consistent, and unambiguous system design model. The integrated MBSE design model contains system functional and logical representations with the physical detailed design implementation to specify, analyze, design, and verify that requirements are satisfied. The guidance defines conventions for developing design models to specify system behavior and structure characteristics with traceability to the project’s requirements. The design models provide a digital authoritative source of truth information repository for a project’s technical baseline. Model simulation with test cases facilitate initial design verification in digital computing environments to discover and resolve design defects before incurring the expense of producing physical prototypes.

MBSE practices transform SE from the current document-based approach to employing computer aided design tools comparable to the evolution of the EE, ME, SW, and SP disciplines years ago. The value-added benefit is employment of integrated modeling tools instead of traditional static drawing tools [e.g., PowerPoint, Visio] for product development, integration, and verification across the system lifecycle. The SE&M model-based system design guidance provides MBSE best practices for implementing a digital engineering strategy to develop system design models for specifying and simulating behavior / structure characteristics with traceability to the associated requirements based on the following principles:

  1. Develop, integrate, and employ digital system design models for cross-domain collaboration throughout the product lifecycle [i.e., engineering development, production, and sustainment].
  2. Manage product-lines based on industry open standards with libraries of customized variants adapted for customers with new, modified, and existing [reuse] system design capabilities.
  3. Maintain a digital authoritative source of truth information repository for each product variant’s approved technical baseline throughout the product lifecycle to facilitate collaboration and inform decision making.
  4. Conduct model simulations with verification test cases to evaluate system behavior and structure in digital computing environments to discover design defects before the expense of producing physical prototypes.
  5. Define digital threads of technical key performance parameters and synchronize information across SE, EE, ME, SW, and SP design modeling tools to ensure system requirements, interactions, and dependencies are commonly understood. Design changes are automatically reflected in all model usages across engineering discipline tools and assessed for compliance, with any issue(s) flagged for corrective action.
  6. Utilize “Agile” development processes to provide consistent methods for developing system design models and identifying digital threads for data synchronization across engineering disciplines within the integrated model-based engineering environment.

The SE&M model-based system design approach has a theoretical scientific foundation based on the system phenomenon defined by Hamilton’s Principle: a system is composed of hierarchical elements which interact by exchanging data, energy, force, or mass to modify the state of cooperating elements resulting in emergent, discrete, or continuous behaviors at progressive levels of aggregation or decomposition as shown in Figure 4.

Figure 4: The System Phenomenon – Hamilton’s Principle. (SEBoK Original)

References

Citations

OMG Systems Modeling Language [SysML®] Standard – v1.6, November 2019

INCOSE. 2015. Systems Engineering Handbook - A Guide for System Life Cycle Processes and Activities, version 4.0. Hoboken, NJ, USA: John Wiley and Sons, Inc, ISBN: 978-1-118-99940-0.

Roper, W. 2020. ‘’There is No Spoon: The New Digital Acquisition Reality.’’ Arlington, VA: US Space Force, US Air Force, Assistant Secretary of the Air Force. 07 October 2020. Accessed May 25, 2023. Available at https://software.af.mil/wp-content/uploads/2020/10/There-Is-No-Spoon-Digital-Acquisition-7-Oct-2020-digital-version.pdf.

ISO/IEC/IEEE 15288:2015. Systems and Software Engineering -- System Life Cycle Processes. Geneva, Switzerland: International Organization for Standardization / International Electrotechnical Commissions / Institute for Electrical and Electronics Engineers. ISO/IEC/IEEE 15288:2015.

Schindel, B. 2016. “Got Phenomena? Science-Based Disciplines for Emerging Systems Challenges,” International Council on Systems Engineering (INCOSE), 2016 INCOSE International Symposium Proceedings, Edinburgh, Scotland.

Schindel, B. 2018. “The System Phenomenon, Hamilton’s Principle, and Noether’s Theorem as a Basis for System Science,” International Council on Systems Engineering (INCOSE), 2018 INCOSE International Workshop Proceedings, Torrance, California.

Primary References

INCOSE. 2015. Systems Engineering Handbook - A Guide for System Life Cycle Processes and Activities, version 4.0. Hoboken, NJ, USA: John Wiley and Sons, Inc, ISBN: 978-1-118-99940-0.

ISO/IEC/IEEE. 2015. Systems and Software Engineering -- System Life Cycle Processes. Geneva, Switzerland: International Organization for Standardization / International Electrotechnical Commissions. ISO/IEC/IEEE 15288:2015.

Additional References

U.S. DOD. 2018. ‘’Digital Engineering Strategy.’’ Arlington, VA: Office of the Deputy Assistant Secretary of Defense for Systems Engineering. June 2018.

Wasson, C. 2006. System Analysis, Design, and Development – Concepts, Principles, and Practices.’’ Hoboken, NJ: John Wiley & Sons.

Madni, A. M. and Sievers, M. 2018. Model‐based systems engineering: Motivation, current status, and research opportunities, Systems Engineering. 2018; 21: 172– 190. https://doi.org/10.1002/sys.21438

Estefan, J. 2008. A Survey of Model-Based Systems Engineering (MBSE) Methodologies, rev, B. Seattle, WA: International Council on Systems Engineering. INCOSE-TD-2007-003-02. Accessed April 13, 2015. Available at http://www.omgsysml.org/MBSE_Methodology_Survey_RevB.pdf.

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