Chapter 1

Introduction

Systems and Systems Engineering

Systems engineering and systems science has become one of the most important, comprehensive, and fundamental fields, and has wide application in almost every area of our society; from the macromanagement of government to the daily production of manufacturing facilities, from the development of spacecraft to the design of small consumer products, systems engineering is being applied at all times, at different levels. As one of the engineering disciplines, systems engineering studies systems; in this first chapter of the book, we will review the basic scientific concepts of systems, understand the background for systems science, and examine the evolvement of systems and systems engineering from a historical perspective. This will help readers to understand the origin of systems science and the need for systems engineering. In this chapter, we will first define systems and systems engineering, describe the unique characteristics of systems engineering, and give a brief historic introduction to systems engineering development.

1.1 Systems

The term system is no stranger to us; we have been exposed to different kinds of systems since our early school years. According to the Oxford English Dictionary, a system is “a set of connected things or parts forming a complex whole,” or “a set of principles or procedures according to which something is done; an organized scheme or method.” Although the basic definition does not change, the term means slightly different things in different disciplines; for example, in physiology, human systems are sets of organs working together to serve common human physiological functions, such as the human nervous system, which serves as the body control center and communications network for the human body; or the human digestive system, which turns food into the energy humans need to survive and process food residue and waste for disposal. For human factor professionals, a system is the combination of human, machine, and the surrounding environment. For systems engineering, we must define “system” more specifically:

A system can be broadly defined as a set of integrated components that interact with each other and depend upon each other, to achieve a complex function together. A system can be decomposed into smaller subsystems or components and a system may be one of the components for a larger system.

The following characteristics are present in all systems:

• A system has a main function or a meaningful purpose. To perform a function, a system takes input and generates output through the mechanism defined in the system structure. Systems’ functions, functional models, and analyses are illustrated in greater detail in Chapters 3 and 4. In this chapter, we briefly introduce the function’s concepts. For example, an automobile system’s function is to transport humans/goods to destinations. To perform this function, the system receives inputs and energy that allow the driver to start, control and drive the system get to the destination location; its inputs include the driver’s control and energy provided by the gasoline or electricity, and the output of the system is the velocity change (momentum).
• A system has a hierarchical structure. As seen in the definition, a system usually consists of many subsystems that can also be smaller-scale systems; meanwhile, a system is usually a subsystem of a higher-level system. For example, our planet is a large biological system, consisting of many smaller systems, such as the ocean and continents. Planet Earth is simultaneously a subsystem of the larger solar system.
• A system has interacting subsystems and components that interact with each other. Components’ interactions are necessary for achieving the system’s functions. A system is not simply the sum of all components, but rather it is an integrated whole package of the subsystems and components working in a well-defined hierarchical structure.
• A system has a life cycle. The system life cycle is the time span that starts from the concept of the system, continuing through the exploration of the concept, design and development, system operation, and maintenance, until the system is retired and discontinued.
• A system has reliability. No system is 100% reliable and error free. As Murphy’s law states, “Anything that can go wrong will go wrong” at some point. One of the most important design objectives is to keep Murphy’s law in mind and make the system more reliable.

More formally presented, systems have the following elements:

1. Subsystems and components: These are the fundamental constructs/functional units for systems. If desired, systems can be decomposed almost infinitely, all the way to the microworld level, such as electrons and atoms. For most design purposes, it is not necessary to decompose a system to this level of depth. As a rule of thumb, the decomposition usually stops at the assembly level, that is, at the level at which the commercial off-the-shelf (COTS) items can be obtained externally. The lowest level of assembly components and the other levels of the system are called subsystems. Subsystems are described through a hierarchical numbering system such as 2.0, 2.1, 2.1.1; by definition, 2.1 is a subsystem of 2.0, and 2.1.1 is a subsystem of 2.1. The hierarchical modeling approach will be illustrated in greater detail in Chapter 4. It is important to note that the subsystem and components may sometimes not be tangible hardware items. Depending on the nature of the system, some components can also be software, human, or even information.
2. Systems components have attributes. These attributes, often called design-dependent parameters (DDP), define and specify the systems components. For example, the physical dimensions of a component, mean time between failures (MTBF), power input and output, and so on. The purpose of systems design, to some extent, is to derive these quantitative and qualitative attributes from the systems requirements, so that specific system components can be built or obtained.
3. Systems components and subsystems interact and regulate system behaviors through different relationships. A system starts with user/customer requirements; requirements are the basis for systems functions; higher-level requirements can be refined by lower-level requirements; higher-level functions are decomposed by lower-level functions. Each function is performed by one or more components. These relationships are essential for successfully translating the systems requirements into component attributes, providing system rationale, and providing traceability for systems design activities. Systems design and modeling, including the specification of the system components and their relationships, is discussed in greater detail in Chapters 3 and 4.

Let us illustrate the systems concepts above with the example of a fixed-wing airplane (such as a Cessna 172). The function of a fixed-wing airplane is flight. In order to achieve this function, an airplane needs to have the necessary components; these components are used to construct the airplane, and they work together and interact, for the airplane to be able to take off, cruise, and land safely. Meanwhile, the components must be able to communicate with other airplanes and air traffic controllers. Among fixed-wing airplanes, major components are the airframe and propulsion systems. The airframe subsystem can be further decomposed into smaller subsystems, such as fuselage, empennage, wing, landing gear and so on. The empennage subsystem consists of stabilizers, rudders, tabs, and elevators. Propulsion systems consist of components such as the power-plant subsystem (the engine) and electrical control systems (avionics). These smaller components are themselves a system on a smaller scale, which can also be further decomposed into smaller components, if desired. All the components work and interact with each other to provide some kind of function, in order to serve the bigger system’s functions.

1.2 Systems Classification

Depending on the perspectives from which a system is studied, it can be classified into different categories. Understanding the system categories can help us to narrow the scope of the systems and derive common system characteristics. In categorizing the system, one has to keep in mind that none of the classifications makes a clear cut, and furthermore, any subsystem might belong to several different categories; for example, a man-made system could be dynamic and closed-loop controlled. Generally speaking, a system can be classified into one or more of the following categories: natural or man-made system, static or dynamic system, conceptual or physical system, and open or closed system.

1.2.1 Natural Systems versus Man-Made Systems

A natural system is a self-organized system that nature formed after millions of millions of years’ selection and development. Examples of natural systems are the planet, oceans, and natural lakes. A natural system sustains itself by self-organizing to a state of equilibrium, for example, the food chain in a natural lake. Any disturbance to this equilibrium can be devastating for the natural system. A man-made system, on the other hand, is made by humans. Man-made systems, such as computers or automobiles, cannot be obtained from nature, but only through the creative efforts of humans. Systems engineering studies man-made systems as objects, with less concern for natural systems. One has to keep in mind, however, that there is no absolute isolation between natural systems and man-made systems. As a matter of fact, man-made and natural systems constantly interact with each other and sometimes make a huge impact on each other. Man-made systems often need inputs from nature (i.e., the automobile needs gasoline, which is made from crude oil from the natural world) and rely on nature to process the waste generated (e.g., the greenhouse gases from the automobile). With more advances in our technological development, man-made systems are becoming more complex and powerful, which requires more resources from Mother Nature. Meanwhile, more waste returns back to nature, often polluting and causing the natural environment to deteriorate. Industrial pollution is becoming a more serious problem now, and with more awareness from humans, environmentally friendly systems designs have become part of system competitiveness and advantages.

1.2.2 Static Systems versus Dynamic Systems

Systems can also be classified as static or dynamic. Static systems are those structural systems that do not change their state within a specified system life cycle, such as a bridge, a building, or a highway. A dynamic system is one where its state, or the state of its components, changes over time, either in a continuous or discrete manner. A dynamic system’s state can be considered a function of time, its change taking place at either a more deterministic rate or a more stochastic rate (think of a large service center’s change of state as customers arrive in a random pattern). Similarly to natural versus man-made systems, the distinction between static and dynamic systems is relative, not absolute. Depending on the different perspectives from which a system is being analyzed, a system may be considered static or dynamic. For example, from Earth, within a short period of time, the Great Wall of China is considered a static system; however, if one observes it from outer space, the Great Wall is certainly moving, although at a very slow speed. While there may be no absolutely static systems, within the context of systems engineering, we treat some fixtures or structures as static. By doing so, we can simplify the problem, as we need to focus only on their dynamic components. For example, when we study operations within a production facility, the facility building is considered static; we only need to concentrate on the dynamic aspects of the system, such as material flows and human activities to investigate the effectiveness of production management.

1.2.3 Conceptual Systems versus Physical Systems

Our world comprises physical systems, and physical systems consist of objects that can be seen, touched, and felt. Natural systems such as animals, bacteria, lakes, and humans are all physical systems; physical systems also include man-made systems, such as the computers, appliances, tools, and equipment that we humans use on a daily basis. Conceptual systems are those consisting only of concepts, not real objects, so we cannot visually see or physically touch these systems. Conceptual systems illustrate the relationships among objects and allow us to understand the system and communicate details about the system’s structures and mechanism. A simulation model of a factory operation process, a blueprint of the machine assembly, or the information processing model of human cognition and perception would be examples of conceptual systems. Science and mathematics are the fundamentals of conceptual models. A conceptual model can be general for a wide range of objects or it can be specific for a certain physical system. In systems engineering, conceptual modeling serves as a basis for the physical system. Before the actual physical systems are manufactured, parts procured and systems assembled, a conceptual model is usually built first to allow us to analyze the feasibility of such a system and assess the fundamental characteristics of system performance. Data collected from conceptual models helps designers to make the necessary adjustments; it is usually cheaper and quicker to modify a conceptual system than a physical system. Conceptual systems design is a very critical step for systems engineering design, as most of the systems analysis occurs at this stage and most systems specifications will be determined in the conceptual model. From a conceptual model, a physical model can be easily derived. Conceptual design will be covered in Chapter 2.

1.2.4 Open Systems versus Closed Systems

Systems can be classified based on their interaction with the environment. Open systems exchange information, matter, or energy with their surrounding environments, while closed systems do not exchange such things. In a very strict sense, there is no absolutely closed system existing in the universe, while any system can be more or less considered an open system. Generally speaking, systems are thought of as closed systems when the exchange of matter, information, or energy can be ignored. In physics, closed systems are further classified as closed systems or isolated systems. An isolated system has no exchange of anything with the outside environment, but when only energy is exchanged, the system is closed but not isolated. An isolated system is an ideal closed system, which is practically nonexistent, but closed systems can be found in our daily life, such as a sealed container of water or gas. In thermodynamics, the laws of thermodynamics requires the system to be classified exactly as isolated, closed, or open; thus, system energy and entropy (the amount of energy used for work) can be determined. Open or closed systems concepts also apply in engineering systems and social systems, with different components: large numbers of biological objects or groups that interact with each other, rather than physical particles or objects. In systems engineering, a system is considered open—especially when one takes a life cycle perspective—if the system interacts with the environment and its impact on the environment is one of competitive advantage that system design should include in the early development stages.

Besides the four types of classification, systems can also be classified into other different categories. For example, in system simulation, we often distinguish between continuous systems and discrete systems; in the business and management field, there are manufacturing systems and services systems. The classification is really dependent on the specific system we are studying and the objective of the study.

System science and systems engineering have developed along with the development of technology. System concepts and systems thinking have become more critical in industry, especially after the industrial revolution; manufacturing has been transformed from human labor-based, small-scale workshops to large factories using complex machinery systems. The transition to the machine age enabled many new machines to be developed; machines gradually replaced human labor in many areas, freed humans from repetitive and dangerous work, increased work efficiency, and in turn made more advanced machines to achieve more complex functions and tasks. After many decades of machine age development, technology has served and replaced almost every aspect of our everyday life, including the manufacturing sector. Now, we can build a new machine without worrying about the details or the fundamental parts of the machines, as we can find the parts to assemble them quickly. The focus has now shifted from the machine age to the system age. The new problem is not to make a single device work; it is how to use the available technology to build something more complex, more powerful, more user friendly, and more efficient. When we begin building systems, systems thinking becomes more important than at any time previously. We need to have the big picture first, just as when we draw a large picture, we compose and sketch the system structure first before we put in any details and colors. A good design process will ultimately determine the success of the system, and the philosophy of the big picture, carried out by a structured process, is called systems engineering. In the next section, we will define systems engineering, review its fundamental features as well as its historical perspective, and introduce the profession of systems engineering.

1.3 Systems Engineering

Before we get into systems engineering, let us first talk about engineering. Engineering, according to the American Board for Engineering and Technology (ABET n.d.), is

the profession in which a knowledge of the mathematical and natural sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize, economically, the materials and forces of nature for the benefit of mankind.

It is the application of what we discover from science in man-made systems. Systems engineering, similarly, applies the knowledge, theories, models, and methods of systems sciences, based on the philosophy of systems thinking, to guide in designing man-made systems. The International Council on Systems Engineering (INCOSE 2012) defines systems engineering as follows:

Systems engineering is 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: operation, performance, test, manufacturing, cost and schedule, training and support and disposal. 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.

In all the systems engineering books available, there are some variations on the definition of systems engineering, but regardless of what definition is being used, systems engineering has the following common characteristics:

1. It is an applied science. Systems engineering applies scientific discoveries and mathematics to make a specific system work. Note we say specific here; that is because systems engineering does not really address the creation of general scientific theory, nor does it work for all systems. Its results only work for a specific system, not every system in general.
2. Systems engineering is concerned with the big picture of the system: it is top-down design processing, as opposed to starting with detailed bottom-up processing. In systems engineering, a system starts with a need that comes from the users/stakeholders of the system. This need is translated into concepts and is expressed in the format of systems requirements. Systems engineering design is driven and guided by requirements, which follows a structured iterative design process that constantly involves “analysis-synthesis-evaluation.” Through this process, the details of the systems are gradually evolved into tangible, visible physical systems. The systems engineering process is a translation process, transforming users’ needs into a working system through guided procedures and proper use of models and analytical methods. In this process, critical thinking and rigorous reasoning (top-down thinking) as well as creative thinking are both important for the success of the system. In turn, systems engineers are required to have a broader scope of knowledge and skills, compared to other traditional engineers; as we will see later, systems engineering is a general design philosophy, which can be applied to all kinds of complex systems design, including aerospace, aeronautics, manufacturing, software, transportation, and so on, to name a few, with special tailoring to the system being designed. A systems engineer not only needs a good understanding of the nature of the system, understanding of the domain knowledge of that specific system, knowledge of how the system works—at least at a high level—but also have the ability to coordinate with different engineers in the design team. Thus, systems engineers need to have both knowledge of big-picture system thinking and good communication skills. A good systems engineering team is often the core determinant of a system’s success.
3. Systems engineering is a multidisciplinary field. As we have discussed the systems engineering process, we have mentioned that systems engineering is multidisciplinary in nature; it is essentially team work. Arthur David Hall III (1969) proposed a three-dimensional morphology of systems engineering: time, logic and profession. The time dimension defines the major design phrases and milestones of the system development processes; the logic dimension defines the logical models and steps through which a system would evolve, similar to the system’s life cycle status, including problem definition, design, synthesis, decision making, optimization, planning and actions, and so on. The third dimension, profession, describes the different professions that are involved in systems engineering work. Systems engineering professions include management, designers and engineers, graphical artists, and supporting technicians. Compared to several decades ago, at the present time the extent of this range of professions has expanded a great deal, due the scope and complexity of systems we are designing, which have arrived at a different level. With the advanced development of current technology in computing and the Internet, and the fast-growing trend of globalization and supply chain management, there are remarkable increases in the number and scope of professions. The current disciplines and professions involved can be summarized in four different categories:
   1. The art and science domain: This is the fundamental scientific knowledge pertaining to systems concepts and system analysis methods and models, including applied mathematics (operations research), human-related science (psychology, physiology), graphical design, architecture, environmental science, natural science, biology, and so on. The main mathematical model used in systems engineering is operations research, an applied field in mathematics.
   2. The engineering domain: Engineering teams are a core operational part of any systems design. Depending on different types of systems, the relevant engineering disciplines are included as a part of the systems design team. Moreover, in terms of system-level planning, scheduling and optimization, industrial engineering, human factors engineering, and management science are among the most relevant fields for systems engineering.
   3. The management domain: In the current globalized environment, any business faces competition from all over the world. Utilizing the global supply chain is an essential part of core competitiveness for any business, translating to systems designers making management a more important role in the design and distribution process. For an effective design, management must not only provide a framework to manage and control the design team and its efforts, but also, more importantly, build a culture and management style that encourages and motivates employees, reinforcing user loyalty throughout the system life cycle and design process. Almost all management functions play a role in the design, including human resources, accounting, finance, and marketing. These functions provide an external liaison for the systems design teams and make the internal operations more efficient as well.
   4. Supporting roles: Besides all the key players in systems design, as mentioned above, there are also personnel that support the design efforts, sometimes indirectly, such as the information technology technicians, legal department specialists, test and equipment technicians, and others. These support functions make sure the daily design activities are carried out smoothly, which is also essential for any design team.

The main professional association for systems engineering is the International Council on Systems Engineering (INCOSE). INCOSE is a nonprofit organization dedicated to the field of systems engineering. Founded in 1990, INCOSE has over 9000 members (as of December 2013) all over the world, representing a wide range of expertise and backgrounds from industry and academia. The main mission of INCOSE is to “share, promote and advance the best of systems engineering from across the globe for the benefit of humanity and the planet” (www.incose.org). INCOSE offers professional training and certification in systems engineering; for more information, refer to www.incose.org.

1.4 Brief History of Systems Engineering

Systems engineering is a relatively young field, compared to other engineering disciplines. However, its fundamental concept, system science, can be traced back to ancient literature as early as the eighteenth century, when science knowledge exploded, especially in the natural and physical sciences. The creation of structure in different areas of scientific knowledge set in motion the development of system science. Since then, the fundamental concepts of system science have been presented in many scientific disciplines.

1.4.1 From Reductionism to System Thinking

There are two major milestones in the development of system science that led directly to the growth of the field of systems engineering: the machine age and the system age. They are based on different views of systems. The machine age is largely based on reductionism. Reductionism is a philosophical view of science. It is based on the principle of causality, that is, a system behavior can be explained completely by its fundamental elements or components; it holds the premise that the components of a system are the same when examined separately. Since the early nineteenth century, with the development of new technology, devices and tools, such as the steam engine, the industrial revolution has marked a turning point for modern manufacturing and production. More and more advanced machinery has been developed to replace human power; machines have been developed to achieve more sophisticated functionality. The main principle for designing these machine systems are cause-effect control systems, which are the main characteristic of the machine age. The focus was on designing the control mechanism for the machine; and by integrating different components together, a bigger system can be built. In the machine age, the design of systems largely depends on the reductionism principle, following a bottom-up process. As the technology for individual machines becomes more developed and system development moves toward to a more complex level, reductionism has started to show its limitations when dealing with increasing levels of complexity.

Using reductionism, design methods could fail, especially when applied to complex phenomena such as human society, biological sciences, behavioral sciences, and managerial sciences, as these systems are difficult to examine as isolated entities, and the system is not simply the sum of its elements in a linear manner. The systems approach, however, is more holistic, and follows the concept of expansionism. A system approach argues that even if every part is performing well for its objective, the total system might not be performing well for the system objective if the parts are imperfectly organized (Parnell et al. 2008).

System design moved from the lower level of the machine age to the system age. In the system age, systems approaches look at systems as an integrated whole unit, with the composed components interacting together to serve the systems’ purposes, often in a nonlinear manner. The unique characteristic of the system age is the design of systems from a top-down approach; instead of looking at individual components first, system thinking starts with the system as a whole at the beginning, by looking at the big picture of the system, identifying the objectives (requirements) of the system, and having the objective to direct the design of the system. After decades of continuous evolution, systems engineering has become the standard approach for complex system design. In the following section, major historical events area described to briefly show the evolution of systems engineering.

1.4.2 Early Practices

The first recognizable use of the systems approach was in the telephone industry in the 1920s and 1930s. It was Bell Telephone Laboratories who first used the term “systems engineering” in the 1940s. The concepts of systems engineering within Bell Laboratories traces to the early 1900s and describes major applications of systems engineering during World War II. At that time, a group of U.S. and British scientists from various disciplines tried to resolve the problem of achieving the optimal military strategies and actions using limited resources. These practices directly led to the birth of an applied mathematics, known as operations research, now a major applied mathematical methodology used in systems engineering. The application of operations research proved substantial through its successful application to military operations. Around the same time, the National Defense Research Committee established a Systems Committee with Bell Laboratories support to guide a project called C-79, the first task of which was to improve the communication system of the Air Warning Service.

In 1946, the Research and Development (RAND) Corporation was founded by the United States Air Force; the systems analysis applied within RAND has been considered an important part of systems engineering development. It was the first to propose and utilize the “system analysis” approach and demonstrate its significance. During this time, the first formal attempt in history to teach systems engineering started at the Massachusetts Institute of Technology (MIT) in 1950 by G.W. Gilman, the director of systems engineering at Bell Laboratories. With the wide application of operations research and control theory, together with the development of digital computers, the scientific foundation for systems engineering has been established.

1.4.3 Government Role

Government has played an important historical role in promoting systems engineering, since most of the early complex systems were requested by government. With more demand for and experience in developing large complex systems, the need to identify and manipulate the properties of a system as a whole—which in complex engineering projects may differ greatly from the sum of the parts’ properties—motivated agencies such as the Department of Defense (DoD) and National Aeronautics and Space Administration (NASA) to pay more attention to applying systems engineering discipline. Since the late 1940s and early 1950s, the DoD has applied a systems engineering approach to the development of missiles and missile-defense systems. This undertaking was recognized as the Intercontinental Ballistic Missile (ICBM) Program, later the Teapot Committee, and it served as one of the key historical foundations of systems engineering. The ICBM was an idea given by Bernard Schriever to the Teapot Committee in 1954, and it ultimately changed the organizing principles of managing a systems development contract. From this point on, “there would be a System Engineering contractor staffed by ‘unusually competent’ scientists and engineers to direct the technical and management control over all elements of the program” (Hallam 2001). The Teapot Committee helped establish systems engineering as a discipline by “creating an organization dedicated to the scheduling and coordinating of activities for subcontractor R&D, test, integration, assembly, and operations” (Hallam 2001). The coordination required for the system approach to the project was further driven by schedule demands containing concurrent development of designs, subsystems, manufacturing, and so on. It was then, through trial and error, that quantitative tools and methodologies were developed. These very tools formed the basis for the interdisciplinary trade studies and decision aids that enrich the field of systems engineering.

By the 1960s, degree programs in the discipline of systems engineering became widely recognized across U.S. universities and many systems engineering-related techniques were developed within more academic research and industry applications. For example, in 1958 the Program Evaluation and Review Technique (PERT) was developed by the United States Navy Special Projects Office for the Polaris missile system. PERT is a scheduling method designed to plan a manufacturing project by employing a network of interrelated activities, coordinating optimum cost and time criteria. PERT emphasizes the relationship between the time each activity takes, the costs associated with each phase, and the resulting time and cost for the anticipated completion of the entire project. Since existing large-scale planning was inadequate at the time, the Navy teamed up with the Lockheed Aircraft Corporation and the management consulting firm of Booz, Allen, and Hamilton, working in large-scope systems engineering efforts. Traditional techniques such as line of balance, Gantt charts, and other methods were found limited in dealing with variability, and PERT evolved as a means to deal with the varied time periods needed to finish the critical activities of an overall project.

By the mid-1960s, in response to many contractors expressing a need for greater latitude in applying alternative systems engineering techniques, several criteria-oriented military standards were issued, including MIL-STD-499A. Army FM 770-78 and MIL-STD-499A formed the foundation for the current application of systems engineering concepts and requirements in military development programs. It was in the late 1950s and 1960s that the emergence of engineering discipline “specialists” on most development programs occurred.

In 1962, Arthur Hall published his first book on systems engineering: A Methodology for Systems Engineering. Hall was an executive at Bell Laboratories and was one of the people who were responsible for the implementation of systems engineering at the company. Hall reasoned that systems engineering was important because products were increasing in complexity, the needs of consumers were expanding, the business markets were growing rapidly, and there was an acute shortage of technically and scientifically trained people handling the complex systems design. Systems engineering was in great demand in this era. According to Hall, systems engineering is a function with five phases: (1) systems studies or program planning; (2) exploratory planning, including problem definition, selecting objectives, synthesis and analysis, selection, and communication; (3) development planning; (4) studies during development, including system components development and integration and testing of components; and (5) current and emerging engineering, that is, current engineering technology and that which will exist while the system is operational (Buede 2009). Hall’s book is considered a major milestone for systems engineering education.

In the 1960s, a third defining moment for systems engineering was seen: the birth of NASA’s Apollo program, which lasted from 1961 to 1972. In fact, the Apollo program is probably the most classic example of systems engineering in practice to date. The task of sending humans to the moon was daunting and complicated; it involved breaking the underlying goal into multiple sections or manageable parts that participating agencies and companies could work with and comprehend. These various parts then had to be reintegrated into one whole solution, and as a result, careful attention and management involving extensive testing and verification was necessary. The complex nature of these tasks made systems engineering a suitable tool for designing such systems. It was the principles of systems engineering that resulted in the rigorous system solution which contributed to Apollo’s overall success.

In 1972, the International Institute for Applied Systems Analysis (IIASA) was founded, with the intention of applying techniques of systems analysis to solve urban, industrial, and environmental problems that transcended international boundaries. Members of the IIASA discussed hallmarks of the IIASA approach to problem solving, which included interdisciplinary emphasis and the maintenance of credibility with both scientist and decision makers (Hughes, n.d.). The IIASA approach is illustrated in the organization’s most successful venture: a transboundary air pollution project using the Regional Acidification Information and Simulation (RAINS) model of the impact of acidification in Europe. With efforts such as these, systems engineering has emerged from the government and military fields to almost every area of the industrial and social, and moved to a more comprehensive and advanced stage: the information age.

1.4.4 Information Age

With the development of hardware and software, computer technology made tremendous advances in the 1980s and more in the 1990s, which marked the beginning of the information age, or computer age/digital age. With fast- growing and innovative technologies such as the internet, humans have achieved an era of most effective, rapid technological growth than at any previous time. More and more complex, technology-driven systems are being designed every day, creating a new technological world for a wide range of users. With the shift from traditional industry to a highly computerized economy, the degree of complexity involved in the systems has reached a new high level. The increasing level of complexity has put the practice of systems engineering in greater demand. With the blooming of information technology, limited resources dwindling, and a more competitive market, the world has started a whole new chapter, characterized by globalization and the use of the supply chain in the design process. It is hard to believe that, at the current time, any organization or business is not using some kind of global supply chain for their operations. Having an efficient systems integration process is essential for the success of any complex system design. In the information age, or system age, it is hard to find any complex system which does not follow a systems engineering approach. Nowadays, systems engineering has become a well-accepted standard for practice across government and industries internationally.

In 2009, CNN Money ranked systems engineer as no. 1 in the list of the best jobs in the United States, according to CNN.com:

demand is soaring for systems engineers, as what was once a niche job in the aerospace and defense industries becomes commonplace among a diverse and expanding universe of employers, from medical device makers to corporations like Xerox and BMW.

After several decades, systems engineering has now grown into a profession; it is a must-have function and department for most of the large corporations, and the major association for systems engineering, INCOSE, has grown significantly since its formation in 1990. Now, INCOSE has more than 9000 members globally, and is still growing every year. Meanwhile, government and industrial organizations are still facing a significant shortage of systems engineers, especially senior-level expert systems engineers; careers in systems engineering will become more abundant in the near future. That is the reason why we are here, to study this subject.

1.5 Summary

Systems engineering has become one of the most important engineering fields in every aspect of our society. It is based on systems concepts and the philosophy of the big picture first, in order to bring complex systems into being from beginning to end in the most efficient manner. This first chapter reviewed the basic concepts of systems, systems science, systems engineering, and the historical evolvement and development of systems engineering. Knowing this basic information about systems will help us understand the origin and need for systems engineering and thus grasp better the ideas and models in systems engineering.

Problems

4. Define systems. What are the characteristics of systems?
5. Give an example of a system within the systems engineering context. Identify the basic elements involved.
6. What are the system classifications? Briefly discuss these classifications and give examples (other than those examples given in the book).
7. Define science and engineering. What is the difference between science and engineering?
8. What is reductionism and what is expansionism? Briefly discuss the difference between these two terms.
9. Describe the main historical phases of systems engineering development and the main development milestones for each phase.