# Systems Engineering Demystified  ## Metadata - Author: Jon Holt and Tim Weilkiens - Full Title: Systems Engineering Demystified - Category: #system-architecture ## Highlights - Often, the discipline of Systems Engineering is noticed primarily when it is not present. ([Location 30](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=30)) - The main tenet of systems theory is that it is a conceptual framework based on the principle that the component parts of a system can best be understood in the context of the relationships with each other and with other systems, rather than in isolation ([Location 193](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=193)) - A System will be defined in different ways by different people, depending on the nature of the System. ([Location 213](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=213)) - Natural Systems, which represent open Systems whose characteristics are beyond the control of humans. Such Systems include weather systems, nature, the environment, time, and so on. ([Location 220](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=220)) - Designed Physical Systems, which represent what most people would immediately think of when considering a System, such as smartphones, tablets, helicopters, cars, trains, planes, spaceships, boats, TVs, cameras, bridges, computer games, satellites, and even domestic appliances. The list is almost endless. The Systems will typically consist of physical artifacts that represent the real-world manifestation of the System. ([Location 222](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=222)) - Designed Abstract Systems, which represent Systems that have no physical artifacts but that are used by people to understand or explain an idea or concept. Examples of such Systems include models, equations, thought experiments, and so on. ([Location 225](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=225)) - Human Activity Systems, which are people-based Systems that can be seen or observed in the real world. These Systems will typically consist of different sets of people interacting to achieve a common goal or purpose. Examples of such Systems include a political system, social groups, people-based services, and so on. ([Location 227](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=227)) - Transcendental Systems, which are Systems that go beyond our current understanding. Examples of such systems include deities, unknown problems, and Numberwang. ([Location 230](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=230)) - Any system will have its own natural structure and may be thought of as a set of interacting System Elements, ([Location 242](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=242)) - System is made up of a set of system elements and that there are two types of Systems: a System of Interest and an Enabling System. ([Location 246](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=246)) - A System of Interest refers to a System that is under development, whereas an Enabling System refers to any System that has an interest in, or interacts with, a System of Interest. ([Location 247](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=247)) - In Systems Engineering, everything is connected to something else and so understanding the relationships between System Elements, which form the basis of the interactions between them, is just as important as understanding the System Elements themselves. ([Location 255](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=255)) - Understanding interfaces between System Elements is crucial to be able to specify and define all types of Systems. ([Location 257](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=257)) - One of the key aspects of a System that it is essential to understand as part of any Systems Engineering endeavor is the Stakeholders that are associated with the System, ([Location 262](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=262)) - the definition of a Stakeholder is the role of any person, organization, or thing that has an interest in the System. ([Location 267](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=267)) - Stakeholders are not necessarily people and can be many other things, such as organizations or just about anything. ([Location 276](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=276)) - There is not a one-to-one correlation between Stakeholders and the person, organization, or thing that takes on the role. ([Location 279](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=279)) - Stakeholders lie outside the Boundary of the system, as do Enabling Systems. ([Location 283](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=283)) - Attributes are shown here as relating to the concept of the System but, bearing in mind that a System comprises a number of System Elements, these Attributes may also apply to the System Elements. ([Location 293](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=293)) - These Attributes will typically be represented as nouns that may take on a number of different values and be of a specific, pre-defined type, and may also have specific units. ([Location 294](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=294)) - Dimensions, such as length, width, and height, which would be typed as real numbers and may have units of millimeters associated with them. ([Location 296](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=296)) - Weight, which would be typed as a real number and have the unit of kilograms associated with it. ([Location 298](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=298)) - Element number, which may be an integer and may not have a unit associated with it. ([Location 299](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=299)) - Name, which may be a character/text and may not have a unit associated with it. ([Location 300](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=300)) - Data structures, which may represent an entire audio or video file that complies with a specific protocol, such as MP3, MP4, and so on. ([Location 306](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=306)) - Each System will have at least one Boundary associated with it, which helps to explain the scope of the System, ([Location 309](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=309)) - Physical Boundary: This may be some sort of enclosure that surrounds the System and separates it from the outside world. ([Location 315](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=315)) - Conceptual Boundary: This is a non-Physical Boundary that can be imagined but not necessarily observed. An example of this is the Boundary between a car and the GPS satellite that it interacts with. ([Location 318](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=318)) - Stakeholder Boundary: Different Stakeholders may look at the same System in different ways and, therefore, where they perceive the Boundary of the system to be may change depending on the Stakeholder. ([Location 321](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=321)) - A Need describes the concept of something that shows the purpose of the System. ([Location 342](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=342)) - Requirement: A Requirement represents a statement of something that is desirable for the System to do. ([Location 344](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=344)) - Feature: A Feature represents a higher-level Need of the System that does not necessarily relate to a specific function, but may relate to a collection of functions. ([Location 347](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=347)) - Goal: A Goal is a very high-level Need that represents a Need of the overall System. ([Location 350](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=350)) - All Systems will be limited in some way in terms of how they can be realized, and these limitations are referred to as Constraints, ([Location 356](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=356)) - All Systems will have Constraints associated with them that will limit how the System may be realized, and these are often grouped into a number of categories, ([Location 361](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=361)) - Quality Constraints: In almost all Systems, there will be Constraints that relate to best practice sources, such as standards. ([Location 363](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=363)) - Implementation Constraints: These Constraints will limit the way that the System can be built. ([Location 366](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=366)) - Environmental Constraints: All Systems must be deployed somewhere and many Systems will be defined in a natural environment, which may lead to certain Constraints coming into play. ([Location 369](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=369)) - Safety Constraints: Almost all Systems will have Constraints placed on them that ensure that the System can operate in a safe manner, particularly if things go wrong. ([Location 371](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=371)) - It should also be kept in mind that these Constraints can be complex themselves and actually belong to more than one of these categories. ([Location 375](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=375)) - Constraints are also often described as special types of Needs as they are often represented as being related to specific Needs rather than directly to the System itself. ([Location 379](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=379)) - Systems Engineering is a multidisciplinary approach that takes into account all areas of engineering, including mechanical, electrical, civil, software, and so on. Crucially, however, it should also be recognized that Systems Engineering is not just limited to engineering disciplines, but includes many other diverse areas, such as management, mathematics, physics, psychology, and just about any other area! ([Location 399](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=399)) - Systems Engineering is applied across the entire life cycle of a System and is not restricted to any single stage. ([Location 402](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=402)) - Systems Engineering does not remove the need for intelligence, as systems engineers must never blindly follow instructions, and requires a healthy dose of common sense in order to be effective. ([Location 405](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=405)) - Systems Engineering is a multi-disciplinary, common-sense approach that enables the realization of successful systems. ([Location 408](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=408)) - Fundamentally, there are three main causes for such System failures, which are as follows: Complexity, where Complexity is not identified and, therefore, cannot be managed or controlled. Communication, where communication fails or is ambiguous. Understanding, where different points of view are not taken into account, and assumptions are made. ([Location 414](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=414)) - Essential Complexity is the natural Complexity that is inherent in the system. The term “Essential” is used here as it refers to Complexity that manifests in the essence of the System. ([Location 428](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=428)) - Accidental Complexity is not natural and is introduced by inefficiencies in the people, processes, and tools that are employed to implement Systems Engineering, which will be discussed later in this chapter. ([Location 431](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=431)) - On top of the software itself, the software must be connected to its associated electronic components, which will, in turn, lead to the need for communication buses, such as Controller Area Networks (CANs), which will themselves use communication protocols. ([Location 471](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=471)) - Likewise, there is a whole set of new Constraints associated with Provide a positive driving experience. This increase in the number of Constraints will lead to an increased number of relationships between the basic Needs and Constraints, which will naturally lead to an increase in the Complexity of the Needs and Constraints. ([Location 492](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=492)) - A System of Systems is not just a collection of interacting Systems; it is a collection of interacting Systems exhibiting some behavior that is not exhibited by any of its Constituent Systems. ([Location 502](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=502)) - The key to managing Complexity is identifying where the Complexity lives in a System. ([Location 529](https://readwise.io/to_kindle?action=open&asin=B0BSV5PBRF&location=529))