Synthesizing Possible Solutions

This article considers that part of the systems approach related to the synthesis synthesis of possible solutions options in detail. The final article in this knowledge area, Applying the Systems Approach, considers the dynamic aspects of how this is used as part of the Systems Approach and how this relates in detail to elements of Systems Engineering.

Synthesis Overview

Essential to synthesis is the concept of holism discussed by (Hitchins 2009). It states that a system must be considered as a whole and not simply as a collection of its elements. In SE holism requires that the properties of the whole be determined by considering the behavior of the whole and not simply as the accumulation of the properties of the elements. The latter process is known as reductionism and is the opposite of holism. (Hitchins 2009) puts it this way: “The properties, capabilities, and behavior of a system derive from its parts, from interactions between those parts, and from interactions with other systems.”

When the system is considered as a whole, properties called emergent properties often appear (see Emergence). These properties cannot be predicted from the elements alone. They must be evaluated within the SE effort to determine the complete set of performance levels of the system. According to (Jackson et al. 2010) these properties can be designed into the system, but to do so, an iterative SE approach is required.

In complex systems, individual elements will dynamically adapt to the behavior of the other elements and to the system as a whole. The entire collection of elements will behave as an organic whole. Therefore, the entire SE synthesis effort, particularly in complex systems, must itself be dynamic.

The systems approach aspect of synthesis leads to the SE process of the same name. Preferring to use the terms “design" and "development,” (Wasson 2006, 390-690) describes synthesis from a SE point of view. (White 2009, 512-515) provides a comprehensive discussion of methods of achieving design synthesis.

Defining the System of Interest

The following rules outline the steps for defining the system of interest (SoI). These steps assume that the problem or opportunity that the system is intended to address has previously been identified and understood or, more likely for any non-trivial system, is being identified and understood concurrently with solution synthesis activities.

The steps discussed below are: Identification of the Elements of a System, Division of Elements into Smaller Elements, Grouping of Elements, Identification of the Boundary of a System, Identification of the Function of Each Element, and Identification of the Interactions Among the Elements.

Identification of the Elements of a System

The systems approach calls for the identification of the elements of a system. (Jackson et al. 2010, pp. 41-42) identify the kinds of elements that make up a system. Typical elements treated within Systems Engineering (SE) may be hardware, software, humans, processes, conceptual ideas, or any combination of these. SE defines the properties of these elements, verifies their capability, and validates the capability of the entire system. According to (Page 2009), in complex systems the individual elements of the system are characterized by their adaptability.

In a SE context, according to (Blanchard and Fabrycky 2006, p. 7) elements may be physical, conceptual, or processes. Physical elements may be hardware, software, or humans. Conceptual elements may be ideas, plans, concepts, or hypotheses. Processes may be mental, mental-motor (writing, drawing, etc.), mechanical, or electronic.

In addition to the operational elements of the system under consideration (i.e., a System of Interest, SOI), ISO/IEC 15288 (2008) also calls for the identification of the enabling systems. These are systems utilized at various stages in the life cycle; for example, maintenance and other systems that support the operational elements to solve problems or achieve opportunity.

Today's systems often include existing elements. It is rare to find a true "greenfield" systems in which the developers can specify and implement all new elements from scratch. "Brownfield" systems are much more typical, where legacy elements constrain the system architecture, capabilities, technology choices, and other aspects of implementation. (Boehm 2009)

Division of Elements into Smaller Elements

The next aspect of the Systems Approach is that elements can be divided into smaller elements. The division of elements into smaller elements allows the systems to be grouped, and leads to the Systems Engineering concept of physical architecture as described by (Levin 2009, pp. 493-495). Each layer of division leads to another layer of the hierarchical view of a system. As Levin points out, there are many ways to depict the physical architecture including wiring diagrams, block diagrams, etc. All of these views depend on arranging the elements and dividing them into smaller elements. According to the principle of recursion, these decomposed elements are either terminal elements or are further decomposable.

Grouping of Elements

The next aspect of the systems approach is that elements can be grouped. This leads to the identification of the subsystems essential to the definition of a system. SE determines how a system may be partitioned and how each subsystem fits and functions within the whole system. The grouping of all the elements of a system is called the system of interest (SOI), also called the relevant system by (Checkland 1999, p. 166). The SOI is the focus of the SE effort. According to (Hitchins 2009, p. 61), some of the properties of an SOI are as follows: the SOI is open and dynamic; the SOI interacts with other systems, and; the SOI contains sub-systems. The SOI is brought together through the concept of synthesis.

Identification of the Boundary of a System

Establishing the boundary of a system is essential to SE and the determination of the system's interaction with its environment and with other systems and the extent of the system of interest (SOI). (Buede 2009, p. 1102) provides a comprehensive discussion of the importance and methods of defining the boundary of a system in a SE context.

Identification of the Function of Each Element

The function of a system or of its elements is essential to SE and the determination of the purpose of the system or of its elements. (Buede 2009, pp. 1091-1126) provides a comprehensive description of functional analysis in a SE context.

Identification of the Interactions among the Elements

The next element of the systems approach is the identification of the interactions among the elements. These interactions lead to the SE process of interface analysis. Integral to this aspect is the principle of interactions. Interactions occur both with other system elements and also with external elements and the environment. In a SE context, interfaces have both a technical and managerial importance. (Browning 2009, pp. 1418-1419) provides a list of desirable characteristics of both technical and managerial interface characteristics.

Linkages to other topics

The systems approach principle of synthesis is directly linked to the SE principle of synthesis.

References

Citations

Blanchard, B. and W.J. Fabrcky. 2006. Systems Engineering and Analysis. Upper Saddle River, NJ: Prentice Hall.

Boehm, B. 2009. "Applying the Incremental Commitment Model to Brownfield System Development". Proceedings of the 7th Annual Conference on Systems Engineering Research (CSER), Loughborough, UK.

Browning, T.R. 2009. "Using the Design Structure Matrix to Design Program Organizations". In Sage, A.P. and W.B. Rouse (eds.). Handbook of Systems Engineering and Management," 2nd ed. Hoboken, NJ, USA: John Wiley & Sons.

Buede, D.M. 2009. "Functional Analysis". In Sage, A.P. and W.B. Rouse (eds.). Handbook of Systems Engineering and Management," 2nd ed. Hoboken, NJ, USA: John Wiley & Sons.

Checkand, P. 1999. Systems Thinking, Systems Practice. New York, NY, USA: John Wiley & Sons.

Hitchins, D. 2009. "What are the General Principles Applicable to Systems?" INCOSE Insight. 12(4) (December 2009): 59-63.

INCOSE. 1998. "INCOSE SE Terms Glossary." INCOSE Concepts and Terms WG (eds.). Seattle, WA, USA: International Council on Systems Engineering.

Jackson, S., D. Hitchins and H. Eisner. 2010. "What is the Systems Approach?". INCOSE Insight. 13(1) (April 2010): 41-43.

Jackson, S., D. Hitchins and H. Eisner. 2010. "What is the Systems Approach?". INCOSE Insight. 13(1) (April 2010): 41-43.

Levin, A.H. 2009. "System Architectures". In Sage, A.P. and W.B. Rouse (eds.). Handbook of Systems Engineering and Management," 2nd ed. Hoboken, NJ, USA: John Wiley & Sons.

Page, S.E. 2009. Understanding Complexity. The Great Courses. Chantilly, VA, USA: The Teaching Company.

Shorter Oxford English Dictionary on Historical Principles, 3rd ed. s.v. "Analysis." Oxford, UK: Oxford University Press. 1973.

Wasson, C.S. 2006. System Analysis, Design, and Development. Hoboken, NJ, USA: John Wiley & Sons.

White, Jr., K.P. 2009. "Systems Design." In Sage, A.P. and W.B. Rouse (eds.). Handbook of Systems Engineering and Management, 2nd ed. Hoboken, NJ, USA: John Wiley & Sons.

Primary References

Hitchins, D. 2009. "What are the General Principles Applicable to Systems?" INCOSE Insight. 12(4) (December 2009): 59-63.

Jackson, S., D. Hitchins and H. Eisner. 2010. "What is the Systems Approach?" INCOSE Insight. 13(1) (April 2010): 41-43.

ISO/IEC 2008. Systems and software engineering -- System life cycle processes. Geneva, Switzerland: International Organisation for Standardisation / International Electrotechnical Commissions. ISO/IEC/IEEE 15288:2008.

Additional References

Blanchard, B. and W.J. Fabrcky. 2006. Systems Engineering and Analysis. Upper Saddle River, NJ: Prentice Hall.

Browning, T.R. 2009. "Using the Design Structure Matrix to Design Program Organizations". In A.P. Sage and W.B. Rouse, W.B. (eds.) Handbook of Systems Engineering and Management, 2nd Ed. Hoboken, NJ: John Wiley & Sons.

Buede, D.M. 2009. "Functional Analysis." In A.P. Sage and W.B. Rouse, W.B. (eds.). Handbook of Systems Engineering and Management, 2nd Ed.. Hoboken, NJ: John Wiley & Sons.

INCOSE. 1998. "INCOSE SE Terms Glossary." INCOSE Concepts and Terms WG (eds.). Seattle, WA, USA: International Council on Systems Engineering.

Levin, A.H. 2009. "System Architectures." In A.P. Sage and W.B. Rouse, W.B. (eds.). Handbook of Systems Engineering and Management, 2nd Ed. Hoboken, NJ: John Wiley & Sons.

Page, S.E. 2009. Understanding Complexity. The Great Courses. Chantilly, VA, USA: The Teaching Company.

Wasson, C.S. 2006. System Analysis, Design, and Development. Hoboken, NJ, USA: John Wiley & Sons.

White, Jr., K.P. 2009. "Systems Design." In Sage, A.P. and W.B. Rouse (eds.). Handbook of Systems Engineering and Management, 2nd ed. Hoboken, NJ, USA: John Wiley & Sons

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